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Han Y, Ren X, Liang Y, Ma X, Wang X. Biomechanical effects of transverse connectors on total en bloc spondylectomy of the lumbar spine: a finite element analysis. J Orthop Surg Res 2023; 18:484. [PMID: 37408002 DOI: 10.1186/s13018-023-03977-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Accepted: 07/03/2023] [Indexed: 07/07/2023] Open
Abstract
BACKGROUND The influence of total en bloc spondylectomy (TES) on spinal stability is substantial, necessitating strong fixation to restore spinal stability. The transverse connector (TC) serves as a posterior spinal instrumentation that connects the left and right sides of the pedicle screw-rod system. Several studies have highlighted the potential of a TC in enhancing the stability of the fixed segments. However, contradictory results have suggested that a TC not only fails to improve the stability of the fixed segments but also might promote stress associated with internal fixation. To date, there is a lack of previous research investigating the biomechanical effects of a TC on TES. This study aimed to investigate the biomechanical effects of a TC on internal fixation during TES of the lumbar (L) spine. METHODS A single-segment (L3 segment) TES was simulated using a comprehensive L spine finite element model. Five models were constructed based on the various positions of the TC, namely the intact model (L1-sacrum), the TES model without a TC, the TES model with a TC at L1-2, the TES model with a TC at L2-4, and the TES model with a TC at L4-5. Mechanical analysis of these distinct models was conducted using the Abaqus software to assess the variations in the biomechanics of the pedicle screw-rod system, titanium cage, and adjacent endplates. RESULTS The stability of the surgical segments was found to be satisfactory across all models. Compared with the complete model, the internal fixation device exhibited the greatest constraint on overextension (95.2-95.6%), while showing the least limitation on left/right rotation (53.62-55.64%). The application of the TC had minimal effect on the stability of the fixed segments, resulting in a maximum reduction in segment mobility of 0.11° and a variation range of 3.29%. Regardless of the use of a TC, no significant changes in stress were observed for the titanium cage. In the model without the TC, the maximum von Mises stress (VMS) for the pedicle screw-rod system reached 136.9 MPa during anterior flexion. Upon the addition of a TC, the maximum VMS of the pedicle screw-rod system increased to varying degrees. The highest recorded VMS was 459.3 MPa, indicating a stress increase of 335.5%. Following the TC implantation, the stress on the adjacent endplate exhibited a partial reduction, with the maximum stress reduced by 27.6%. CONCLUSION The use of a TC in TES does not improve the stability of the fixed segments and instead might result in increased stress concentration within the internal fixation devices. Based on these findings, the routine utilisation of TC in TES is deemed unnecessary.
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Affiliation(s)
- Ye Han
- Department of Orthopaedics, Affiliated Hospital of Hebei University, No. 212, Yuhua Road, Hebei, Baoding City, 071000, China
| | - Xuehong Ren
- Hebei University, Hebei, Baoding City, China
| | - Yijie Liang
- Hebei University, Hebei, Baoding City, China
| | - Xiaoyong Ma
- Department of Orthopaedics, Affiliated Hospital of Hebei University, No. 212, Yuhua Road, Hebei, Baoding City, 071000, China
| | - Xiaodong Wang
- Department of Orthopaedics, Affiliated Hospital of Hebei University, No. 212, Yuhua Road, Hebei, Baoding City, 071000, China.
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Borrelli S, Putame G, Audenino AL, Bignardi C, Ferro A, Marone S, Terzini M. Cross-link augmentation enhances CFR-PEEK short fixation in lumbar metastasis stabilization. Front Bioeng Biotechnol 2023; 11:1114711. [PMID: 36937770 PMCID: PMC10020173 DOI: 10.3389/fbioe.2023.1114711] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Accepted: 02/20/2023] [Indexed: 03/06/2023] Open
Abstract
Introduction: Spinal stability plays a crucial role in the success of the surgical treatment of lumbar vertebral metastasis and, in current practice, less invasive approaches such as short constructs have been considered. Concurrently, carbon fiber-reinforced (CFR) poly-ether-ether-ketone (PEEK) fixation devices are expanding in oncologic spinal surgery thanks to their radiotransparency and valid mechanical properties. This study attempts to provide an exhaustive biomechanical comparison of different CFR-PEEK surgical stabilizations through a highly reproducible experimental setup. Methods: A Sawbones biomimetic phantom (T12-S1) was tested in flexion, extension, lateral bending, and axial rotation. An hemisome lesion on L3 vertebral body was mimicked and different pedicle screw posterior fixations were realized with implants from CarboFix Orthopedics Ltd: a long construct involving two spinal levels above and below the lesion, and a short construct involving only the levels adjacent to L3, with and without the addition of a transverse rod-rod cross-link; to provide additional insights on its long-term applicability, the event of a pedicle screw loosening was also accounted. Results: Short construct reduced the overloading onset caused by long stabilization. Particularly, the segmental motion contribution less deviated from the physiologic pattern and also the long-chain stiffness was reduced with respect to the prevalent long construct. The use of the cross-link enhanced the short stabilization by making it significantly stiffer in lateral bending and axial rotation, and by limiting mobiliza-tion in case of pedicle screw loosening. Discussion: The present study proved in vitro the biomechanical benefits of cross-link augmentation in short CFR-PEEK fixation, demonstrating it to be a potential alternative to standard long fixation in the surgical management of lumbar metastasis.
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Affiliation(s)
- Simone Borrelli
- PolitoMed Lab, Politecnico di Torino, Turin, Italy
- Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Turin, Italy
- *Correspondence: Simone Borrelli,
| | - Giovanni Putame
- PolitoMed Lab, Politecnico di Torino, Turin, Italy
- Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Turin, Italy
| | - Alberto L. Audenino
- PolitoMed Lab, Politecnico di Torino, Turin, Italy
- Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Turin, Italy
| | - Cristina Bignardi
- PolitoMed Lab, Politecnico di Torino, Turin, Italy
- Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Turin, Italy
| | - Andrea Ferro
- Oncologic Orthopaedic Surgery Division, CTO Hospital—Città Della Salute e Della Scienza di Torino, Turin, Italy
| | - Stefano Marone
- Oncologic Orthopaedic Surgery Division, CTO Hospital—Città Della Salute e Della Scienza di Torino, Turin, Italy
| | - Mara Terzini
- PolitoMed Lab, Politecnico di Torino, Turin, Italy
- Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Turin, Italy
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Hsieh MK, Liu MY, Tsai TT, Lai PL, Tai CL. Biomechanical Comparison of Different Numbers and Configurations of Cross-Links in Long-Segment Spinal Fixation-An Experimental Study in a Porcine Model. Global Spine J 2023; 13:25-32. [PMID: 33511875 PMCID: PMC9837523 DOI: 10.1177/2192568221990646] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
STUDY DESIGN Biomechanical study. OBJECTIVE Cross-links are a type of common clinical spinal instrumentation. However, the effects of the position and number of cross-links have never been investigated in long-segment spinal fixation, and the variables have not been optimized. We conducted an in vitro biomechanical study by using a porcine long-segment spinal model with 5 different crosslink configurations to determine the optimal construct for clinical practice. METHODS Five modalities with paired segmental screws from T15-L5 were tested in 20 porcine spines. The spines without cross-links composed the control group, Group A; those with a single cross-link from L2-3 composed Group B; those with 2 cross-links from L1-2 and L3-4 composed Group C; those with 2 cross-links from T15-L1 and L4-5 composed Group D; and those with 3 cross-links from T15-L1, L2-3 and L4-5 composed Group E. Spinal stiffnesses in flexion, extension, lateral bending, and axial rotation were compared among 5 different cross-link configurations in 5-level porcine spinal units. RESULTS Flexional, extensional and lateral bending stiffnesses did not significantly change with an increasing number of cross-links or positions in the construct. Axial stiffness was significantly increased with 2 cross-links compared to one (P < 0.05) and with placement more distant from the center of the long spinal fixation construct (P < 0.05). CONCLUSIONS Two cross-links individually placed proximal and distal from the center of a construct is an optimal and efficient configuration to achieve biomechanical stability in non-rigid lumbar spines undergoing long-level fixation.
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Affiliation(s)
- Ming-Kai Hsieh
- Department of Orthopaedic Surgery, Spine
Section, Bone and Joint Research Center, Chang Gung Memorial Hospital and Chang Gung
University College of Medicine, Taoyuan
| | - Mu-Yi Liu
- Ph.D. Program in Biomedical Engineering,
Collage of Engineering, Chang Gung University, Taoyuan
| | - Tsung-Ting Tsai
- Department of Orthopaedic Surgery, Spine
Section, Bone and Joint Research Center, Chang Gung Memorial Hospital and Chang Gung
University College of Medicine, Taoyuan
| | - Po-Liang Lai
- Department of Orthopaedic Surgery, Spine
Section, Bone and Joint Research Center, Chang Gung Memorial Hospital and Chang Gung
University College of Medicine, Taoyuan,Po-Liang Lai, Department of Orthopaedic
Surgery, Spine Section, Bone and Joint Research Center, Chang Gung Memorial
Hospital and Chang Gung University College of Medicine, Taoyuan.
| | - Ching-Lung Tai
- Department of Orthopaedic Surgery, Spine
Section, Bone and Joint Research Center, Chang Gung Memorial Hospital and Chang Gung
University College of Medicine, Taoyuan,Graduate Institute of Biomedical
Engineering, Chang Gung University, Taoyuan,Ching-Lung Tai, Department of Orthopaedic
Surgery, Spine Section, Bone and Joint Research Center, Chang Gung Memorial
Hospital and Chang Gung University College of Medicine, Taoyuan; Graduate
Institute of Biomedical Engineering, Chang Gung University, Taoyuan.
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Is it a requirement or a preference to use cross-links in lumbar instrumentation? JOURNAL OF SURGERY AND MEDICINE 2022. [DOI: 10.28982/josam.7446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Background/Aim: The use of cross-links (CL) is controversial due to reasons such as cost increases and instrument redundancy. While there are many biomechanical studies, the clinical data is limited. The aim of this study is to present the clinical effects of CL by putting forward postoperative clinical outcomes and long-term results of patients with (CL+) and without (CL-) CL augmentation.
Methods: In this retrospective cohort study, patients who underwent lumbar posterior instrumentation with CL+ (n = 164) and without CL- (n = 111) augmentation were evaluated. Demographic data, surgical results, preoperative and postoperative visual analogue scale (VAS), the Oswestry Disability Index (ODI) differences, and pseudoarthrosis and adjacent segment disease (ASD)-related recurrence for more than three years of follow-up were determined. Data of CL+ and CL- groups were compared.
Results: CL+ and CL- groups were similar in terms of age and gender (P = 0.319 and P = 0.777, respectively) There was no difference between the two groups in terms of bleeding amount, duration of surgery, and duration of hospitalization (P = 0.931, P = 0.669 and P = 0.518, respectively). Groups were similar in terms of VAS and ODI differences (P = 0.915 and P = 0.983, respectively), yet there was one case of infection in the CL+ group and two cases of infection detected in the CL- group. There were 13 ASDs in the CL+ group, and eight ASDs in the CL- group. Pseudoarthrosis was seen seven times in the CL+ group, while it was four in the CL- group.
Conclusion: It was observed that adding CL in patients who underwent lumbar instrumentation did not change the early period surgical results. The prevalence of complications was compatible with the scientific literature. In our study, there was no preventive advantage in terms of clinical or postoperative complications found in the use of CL.
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Han L, Yang H, Li Y, Li Z, Ma H, Wang C, Yuan J, Zheng L, Chen Q, Lu X. Biomechanical Evaluation of the Cross-link Usage and Position in the Single and Multiple Segment Posterior Lumbar Interbody Fusion. Orthop Surg 2022; 14:2711-2720. [PMID: 36102202 PMCID: PMC9531066 DOI: 10.1111/os.13485] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Revised: 07/28/2022] [Accepted: 08/09/2022] [Indexed: 12/29/2022] Open
Abstract
OBJECTIVE Previous studies have neither explored the usage of cross-links nor investigated the optimal position of the cross-links in posterior lumbar interbody fusion (PLIF). This study evaluates biomechanical properties of cross-links in terms of different fixation segments and optimal position in single- and multi-segment posterior lumbar interbody fusion. METHODS Two finite element (FE) models of instrumented lumbosacral spine with single-(L4/5) and multi-segment (L3-S1) PLIF surgery were simulated. On the basis of the two models, the benefits of the usage of cross-links were assessed and compared with the status of no application of cross-links. Moreover, the effects of position of cross-links on multi-segment PLIF surgery were studied in Upper, Middle, and Lower positions. RESULTS No significant difference was found in the range of motion (ROM), intersegmental rotational angle (IRA) of adjacent segments, and intradiscal pressure (IDP) regardless of the usage of cross-links in the single-segment PLIF surgery, while the cross-link increased the maximum von Mises stress in the fixation (MSF) under the axial rotation (53.65 MPa vs 41.42 MPa). In the multi-segment PLIF surgery, the usage of cross-links showed anti-rotational advantages indicated by ROM (Without Cross-link 2.35o , Upper, 2.24o ; Middle, 2.26o ; Lower, 2.30o ) and IRA (Without Cross-link 1.19o , Upper, 1.08o ; Middle, 1.09o ; Lower, 1.13o ). The greatest values of MSF were found in without cross-link case under the flexion, lateral bending, and axial rotation (37.48, 62.61, and 86.73 MPa). The application of cross-links at the Middle and Lower positions had lower values of MSF (48.79 and 69.62 MPa) under the lateral bending and axial rotation, respectively. CONCLUSION The application of cross-links was not beneficial for the single-segment PLIF, while it was found highly advantageous for the multi-segment PLIF. Moreover, the usage of cross-links at the Middle or Lower positions resulted in a better biomechanical stability.
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Affiliation(s)
- Lin Han
- Department of OrthopaedicsShanghai Changzheng Hospital, Second Military Medical UniversityShanghaiChina
| | - Haisong Yang
- Department of OrthopaedicsShanghai Changzheng Hospital, Second Military Medical UniversityShanghaiChina
| | - Yongheng Li
- Biomechanics LaboratorySchool of Biological Science & Medical Engineering, Southeast UniversityNanjingChina
| | - Zhiyong Li
- Biomechanics LaboratorySchool of Biological Science & Medical Engineering, Southeast UniversityNanjingChina,School of Mechanical Medical and Process Engineering, Queensland University of TechnologyBrisbaneAustralia
| | - Hongdao Ma
- Department of OrthopaedicsShanghai Changzheng Hospital, Second Military Medical UniversityShanghaiChina
| | - Chenfeng Wang
- Department of OrthopaedicsShanghai Changzheng Hospital, Second Military Medical UniversityShanghaiChina
| | - Jincan Yuan
- Department of OrthopaedicsShanghai Changzheng Hospital, Second Military Medical UniversityShanghaiChina
| | - Luyu Zheng
- School of Medicine, Zhengzhou UniversityZhengzhouChina
| | - Qiang Chen
- Biomechanics LaboratorySchool of Biological Science & Medical Engineering, Southeast UniversityNanjingChina
| | - Xuhua Lu
- Department of OrthopaedicsShanghai Changzheng Hospital, Second Military Medical UniversityShanghaiChina
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Burkhard MD, Cornaz F, Spirig JM, Wanivenhaus F, Loucas R, Fasser MR, Widmer J, Farshad M. Posterior spinal instrumentation and decompression with or without cross-link? NORTH AMERICAN SPINE SOCIETY JOURNAL (NASSJ) 2021; 8:100093. [PMID: 35141657 PMCID: PMC8820010 DOI: 10.1016/j.xnsj.2021.100093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Revised: 11/09/2021] [Accepted: 11/09/2021] [Indexed: 11/29/2022]
Abstract
Background Posterior lumbar instrumentation requires sufficient primary stiffness to ensure bony fusion and to avoid pseudarthrosis, screw loosening, or implant failure. To enhance primary construct stiffness, transverse cross-link (CL) connectors attached to the vertical rods can be used. Their effect on the stability of a spinal instrumentation with simultaneous decompression is yet not clear. This study aimed to evaluate the impact of CL augmentation on single-level lumbar instrumentation stiffness after gradual decompression procedures. Methods Seventeen vertebral segments (6 L1/2, 6 L3/4, 5 L5/S1) of 12 fresh-frozen human cadavers were instrumented with a transpedicular screw–rod construct following the traditional pedicle screw trajectory. Range of motion (ROM) of the segments was sequentially recorded before and after four procedures: (A) instrumented before decompression, (B) instrumented after unilateral laminotomy, (C) instrumented after midline bilateral laminotomy, and (D) instrumented after unilateral facetectomy (with transforaminal lumbar interbody fusion [TLIF]). Each test was performed with and without CL augmentation. The motion between the cranial and caudal vertebrae was evaluated in all six major loading directions: flexion/extension (FE), lateral bending (LB), lateral shear (LS), anterior shear (AS), axial rotation (AR), and axial compression/distraction (AC). Results ROM was significantly reduced with CL augmentation in AR by Δ0.03–0.18° (7–12%) with a significantly higher ROM reduction after more extensive decompression. Furthermore, slight reductions in FE and LB were observed; these reached statistical significance for FE after facetectomy and TLIF insertion only (Δ0.15; 3%). The instrumentation levels did not reveal any subgroup differences. Conclusion CL augmentation reduces AR-ROM by 7–12% in single-level instrumentation of the lumbar spine, with the effect increasing along with the extensiveness of the decompression technique. In light of the discrete absolute changes, CL augmentation may be warranted for highly unstable vertebral segments rather than for standard single-level posterior spinal fusion and decompression.
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Affiliation(s)
- Marco D. Burkhard
- Department of Orthopedics, Balgrist University Hospital, University of Zurich, Switzerland
- Corresponding author.
| | - Frédéric Cornaz
- Department of Orthopedics, Balgrist University Hospital, University of Zurich, Switzerland
| | - José Miguel Spirig
- University Spine Center Zürich, Balgrist University Hospital, University of Zurich, Switzerland
| | - Florian Wanivenhaus
- University Spine Center Zürich, Balgrist University Hospital, University of Zurich, Switzerland
| | - Rafael Loucas
- Department of Orthopedics, Balgrist University Hospital, University of Zurich, Switzerland
| | - Marie-Rosa Fasser
- Institute for Biomechanics, Balgrist Campus, ETH Zurich, Zurich, Switzerland
- Spine Biomechanics, Department of Orthopedic Surgery, Balgrist University Hospital, University of Zurich, Switzerland
| | - Jonas Widmer
- Institute for Biomechanics, Balgrist Campus, ETH Zurich, Zurich, Switzerland
- Spine Biomechanics, Department of Orthopedic Surgery, Balgrist University Hospital, University of Zurich, Switzerland
| | - Mazda Farshad
- Department of Orthopedics, Balgrist University Hospital, University of Zurich, Switzerland
- University Spine Center Zürich, Balgrist University Hospital, University of Zurich, Switzerland
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Sri-utenchai N, Pengrung N, Srikong K, Puncreobutr C, Lohwongwatana B, Sa-ngasoongsong P. Three-dimensional printing technology for patient-matched instrument in treatment of cubitus varus deformity: A case report. World J Orthop 2021; 12:338-345. [PMID: 34055591 PMCID: PMC8152442 DOI: 10.5312/wjo.v12.i5.338] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 04/12/2021] [Accepted: 04/23/2021] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Recently, medical three-dimensional printing technology (3DPT) has demonstrated potential benefits for the treatment of cubitus varus deformity (CVD) by improving accuracy of the osteotomy through the use of an osteotomy guide, with or without a patient-mated plate. Here, we present an interesting CVD case, involving a patient who was treated with corrective biplanar chevron osteotomy using an innovative customized osteotomy guide and a newly designed patient-matched monoblock crosslink plate created with 3DPT.
CASE SUMMARY A 32-year-old female presented with a significant CVD from childhood injury. A computer simulation was processed using images from computerized tomography scans of both upper extremities. The biplanar chevron osteotomy was designed to create identical anatomy between the mirror image of the contralateral distal humerus and the osteotomized distal humerus. Next, the customized osteotomy guide and patient-matched monoblock crosslink plate were designed and printed. A simulation osteotomy was created for the real-sized bone model, and the operation was performed using the posterior paratricipital approach with k-wire positioning from the customized osteotomy guide as a predrilled hole for screw fixation to achieve immediate control of the reduction after osteotomy. Our method allowed for successful treatment of the CVD case, significantly improving the patient’s radiographic and clinical outcomes, with satisfactory result.
CONCLUSION 3DPT-created patient-matched osteotomy guide and instrumentation provides accurate control during CVD correction.
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Affiliation(s)
- Nithid Sri-utenchai
- Department of Orthopedics, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok 10400, Thailand
| | - Nachapan Pengrung
- Department of Orthopedics, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok 10400, Thailand
| | - Korakod Srikong
- Biomechanic Research Center, Meticuly Co Ltd., Chulalongkorn University, Bangkok 10330, Thailand
| | - Chedtha Puncreobutr
- Department of Metallurgical Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok 10330, Thailand
| | - Boonrat Lohwongwatana
- Department of Metallurgical Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok 10330, Thailand
| | - Paphon Sa-ngasoongsong
- Department of Orthopedics, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok 10400, Thailand
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Wang LN, Hu BW, Yang X, Wang L, Xiu P, Zhou CG, Liu LM, Song YM. Loss of Correction After Removal of Spinal Implants in Congenital Scoliosis. World Neurosurg 2020; 144:e916-e925. [DOI: 10.1016/j.wneu.2020.09.110] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Revised: 09/19/2020] [Accepted: 09/20/2020] [Indexed: 10/23/2022]
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Cornaz F, Widmer J, Snedeker JG, Spirig JM, Farshad M. Cross-links in posterior pedicle screw-rod instrumentation of the spine: a systematic review on mechanical, biomechanical, numerical and clinical studies. EUROPEAN SPINE JOURNAL : OFFICIAL PUBLICATION OF THE EUROPEAN SPINE SOCIETY, THE EUROPEAN SPINAL DEFORMITY SOCIETY, AND THE EUROPEAN SECTION OF THE CERVICAL SPINE RESEARCH SOCIETY 2020; 30:34-49. [DOI: 10.1007/s00586-020-06597-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 05/13/2020] [Accepted: 09/05/2020] [Indexed: 12/14/2022]
Abstract
Abstract
Purpose
Dorsal screw-rod instrumentations are used for a variety of spinal disorders. Cross-links (CL) can be added to such constructs, however, no clear recommendations exist. This study aims to provide an overview of the available evidence on the effectiveness of CL, potentially allowing to formulate recommendations on their use.
Methods
A systematic literature review was performed on PubMed and 37 original articles were included and grouped into mechanical, biomechanical, finite element and clinical studies. The change in range of motion (ROM) was analyzed in mechanical and biomechanical studies, ROM, stiffness and stress distribution were evaluated in finite element studies and clinical outcome parameters were analyzed in clinical studies.
Results
A relative consistent reduction in ROM in axial rotation with CL-augmentation was reported, while minor and less consistent effects were observed in flexion–extension and lateral bending. The use of CLs was clinical beneficial in C1/2 fusion, while the limited clinical studies on other anatomic regions show no significant benefit for CL-augmentation.
Conclusion
While CL provides some additional axial rotation stability in most situations, lateral bending and flexion–extension are less affected. Based on clinical data, CL-augmentation can only be recommended for C1/2 instrumentations, while for other cases, further clinical studies are needed to allow for evidence-based recommendations.
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Li T, Ma C, Du YQ, Qiao GY, Yu XG, Yin YH. The Role of Transverse Connectors in C1-C2 fixation for Atlantoaxial Instability: Is It Necessary? A Biomechanical Study. World Neurosurg 2020; 140:e212-e218. [PMID: 32438009 DOI: 10.1016/j.wneu.2020.04.247] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2020] [Revised: 04/29/2020] [Accepted: 04/30/2020] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To investigate the biomechanical effect of C1 lateral mass-C2 pedicle screw-rod (C1LM-C2PS) fixation with and without transverse connectors (TC) in an atlantoaxial instability (AAI) model. METHODS Ten freshly frozen cadaveric specimens were tested using an industrial robot under the following conditions: intact model, AAI model, C1-C2 model, C1-C2 with one TC model, and C1-C2 with two TCs model. Three types of motion, flexion-extension (FE), lateral bending (LB), and axial rotation (AR), were applied (1.5 Nm) to the specimens. The range of motion (ROM) and neutral zone (NZ) between C1 and C2 in all directions were measured. RESULTS Compared with those of the intact and AAI models, the C1-C2 ROM and NZ of all instrumented groups were decreased significantly in each direction of loading motion (P < 0.05). The mean FE ROM in the no TC, 1 TC, and 2 TC groups was 2.12° ± 0.41°, 2.29° ± 0.42°, and 2.04° ± 0.69°, respectively (P = 0.840, 0.981, 0.628, respectively); the mean LB ROM in the 3 intervention groups was 1.26° ± 0.67°, 1.02° ± 0.51° and 1.03° ± 0.57°, respectively (P = 0.489, 0.501, 1.000, respectively). During AR, the ROM and NZ of the no TC group (3.19° ± 0.89° and 1.51° ± 0.42°) were significantly reduced by more than 60% compared with those in the 1 (0.98° ± 0.28° and 0.40° ± 0.11°) and 2 TC groups (1.17° ± 1.69° and 0.42° ± 0.61°) (P < 0.001). Two TCs were equivalent for all loading motions to 1 TC (P > 0.05). CONCLUSIONS Adding TCs to C1LM-C2PS can effectively decrease the axial rotation ROM and enhance the stability of C1-C2 segment. Therefore, it is necessary to use TC-strengthened C1 lateral mass -C2 pedicle screw-rod fixation in patients with instability of C1-C2.
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Affiliation(s)
- Teng Li
- Department of Neurosurgery, The First Medical Centre, Chinese PLA General Hospital, Beijing, China
| | - Chao Ma
- Key Laboratory of Modern Measurement and Control Technology, Ministry of Education, Beijing Information Science and Technology University, Beijing, China
| | - Yue-Qi Du
- Department of Neurosurgery, The First Medical Centre, Chinese PLA General Hospital, Beijing, China
| | - Guang-Yu Qiao
- Department of Neurosurgery, The First Medical Centre, Chinese PLA General Hospital, Beijing, China
| | - Xin-Guang Yu
- Department of Neurosurgery, The First Medical Centre, Chinese PLA General Hospital, Beijing, China
| | - Yi-Heng Yin
- Department of Neurosurgery, The First Medical Centre, Chinese PLA General Hospital, Beijing, China.
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Hong JB, Son DM, Park TH, Woo SH, Lee SJ, Choi UY, Han IB, Chung CK, Kim YJ, Sohn S. Risk of rod fracture according to cross-link position in pedicle subtraction osteotomy (PSO): A finite element study. J Clin Neurosci 2020; 73:304-307. [DOI: 10.1016/j.jocn.2020.01.053] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Accepted: 01/11/2020] [Indexed: 10/25/2022]
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Wang HW, Yin YH, Li T, Yu XG, Qiao GY. Effects of transverse connector on reduction and fixation of atlantoaxial dislocation and basilar invagination using posterior C1-C2 screw-rod technique. Spine J 2019; 19:1995-2002. [PMID: 31254651 DOI: 10.1016/j.spinee.2019.06.021] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Revised: 06/21/2019] [Accepted: 06/24/2019] [Indexed: 02/03/2023]
Abstract
BACKGROUND CONTEXT The mechanical strength provided by internal fixation is crucial for maintaining reduction and facilitating bony fusion. Though satisfactory results with the C1-C2 technique have been acquired in most clinical reports, the related problems of fusion delay and pseudarthrosis still exist. To increase the chance of bony fusion, a transverse connector (TC) is frequently used to augment torsional stiffness of thoracolumbar screw/rod constructs. Nevertheless, the clinical implication of TC in the management of atlantoaxial dislocation (AAD) and basilar invagination (BI) remains largely unknown. PURPOSE To evaluate the effects of TC application on C1-C2 screw-rod constructs based on consecutive adult patients with AAD and BI in a single institution over a 10-year period. STUDY DESIGN A retrospective study. PATIENT SAMPLE Patients with AAD and BI, who were treated with posterior C1-C2 screw-rod technique with or without TC usage from June 2007 to June 2017 at a single institution. OUTCOME MEASURES The radiological measurements included the anterior atlantodental interval (AADI), posterior atlantodental interval (PADI), height of odontoid process above Chamberlain line, and cervicomedullary angle (CMA). Patients' neurologic status was evaluated with the Japanese Orthopaedic Association (JOA) score. Fusion status was evaluated at different follow-up periods. METHODS We compared the difference of clinical, radiological, and surgical outcomes between the TC and NTC groups postoperatively. RESULTS In total, there were 149 consecutive patients in the TC group and 168 patients in the NTC group. On average, 1.2 TCs per patient were used in the TC group. No significant differences were identified for operative time and blood loss between groups. There was also no statistical difference in the radiological measurements of AADI, PADI, Chamberlain line, and CMA between the TC and NTC groups preoperatively and postoperatively. A significantly higher JOA score was obtained in the TC group than that in the NTC group postoperatively. The fusion rates were higher in the TC group than those in the NCT group at the early stage postoperatively (3 and 6 months; p<.01). CONCLUSIONS Use of TCs seems to improve bony fusion and neurologic outcomes in the treatment of AAD and BI with C1-C2 screw-rod technique.
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Affiliation(s)
- Hua-Wei Wang
- Department of Neurosurgery, PLA General Hospital, 28 Fuxing Rd, Haidian District, Beijing 100853, China
| | - Yi-Heng Yin
- Department of Neurosurgery, PLA General Hospital, 28 Fuxing Rd, Haidian District, Beijing 100853, China
| | - Teng Li
- Department of Neurosurgery, PLA General Hospital, 28 Fuxing Rd, Haidian District, Beijing 100853, China
| | - Xin-Guang Yu
- Department of Neurosurgery, PLA General Hospital, 28 Fuxing Rd, Haidian District, Beijing 100853, China.
| | - Guang-Yu Qiao
- Department of Neurosurgery, PLA General Hospital, 28 Fuxing Rd, Haidian District, Beijing 100853, China
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Díaz-Romero Paz R, Sosa Henríquez M, Armas Melián K, Coloma Valverde G. Tendencias de actuación de los cirujanos de columna respecto a la osteoporosis. Neurocirugia (Astur) 2019; 30:268-277. [DOI: 10.1016/j.neucir.2019.04.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Revised: 02/13/2019] [Accepted: 04/17/2019] [Indexed: 01/01/2023]
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Abstract
STUDY DESIGN Retrospective review of a multicenter, prospective database. OBJECTIVE Our aim was to compare complication rates and maintenance of radiographic correction at 2 years after posterior spinal fusion (PSF) with or without cross-links in patients with cerebral palsy (CP)-related scoliosis. SUMMARY OF BACKGROUND DATA Cross-links are frequently used in PSF to correct scoliosis in patients with CP because they are thought to increase the stiffness and torsional rigidity of the construct. METHODS We reviewed the records of patients with CP who underwent primary PSF with or without cross-links between August 2008 and April 2015. Inclusion criteria were minimum follow-up of 2 years, availability of complications data (implant failure, surgical site infection, revision), and pre- and postoperative measurements of the major curve (measured using the Cobb method). The 256 patients included in this analysis had a mean age of 14.1 ± 2.7 years. Ninety-four patients had cross-links (57% using one cross-link; 43% using two cross-links) and 162 patients did not have cross-links. P < 0.05 was considered statistically significant. RESULTS The two groups did not differ significantly with regard to sex, age at surgery, preoperative menarche status, Gross Motor Function Classification System level, major curve magnitude, pelvic obliquity, kyphosis, and lordosis angles. There were no significant differences between groups in the correction achieved or the maintenance of correction at 2 years for the major curve, pelvic obliquity, kyphosis, or lordosis (all P > 0.05). Complication rates were similar between the cross-link group (16%, N = 15) and the non-cross-link group (14%, N = 22). CONCLUSION At 2 years after PSF to treat CP-related scoliosis, patients had no significant differences in the degree of correction achieved, the maintenance of correction, or the rate of complications between those whose fusion constructs used cross-links and those whose constructs did not. LEVEL OF EVIDENCE 3.
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Cross-link is a risk factor for rod fracture at pedicle subtraction osteotomy site: A finite element study. J Clin Neurosci 2019; 66:246-250. [DOI: 10.1016/j.jocn.2019.04.036] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Accepted: 04/29/2019] [Indexed: 12/28/2022]
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Wang T, Cai Z, Zhao Y, Wang W, Zheng G, Wang Z, Wang Y. The Influence of Cross-Links on Long-Segment Instrumentation Following Spinal Osteotomy: A Finite Element Analysis. World Neurosurg 2018; 123:e294-e302. [PMID: 30496922 DOI: 10.1016/j.wneu.2018.11.154] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Revised: 11/16/2018] [Accepted: 11/18/2018] [Indexed: 10/27/2022]
Abstract
OBJECTIVE To develop finite element models of spine following osteotomy and evaluate the effect of number and location of cross-links (CLs) on long-segment instrumentation. METHODS A finite element model of instrumented spine following osteotomy was created from computed tomography images of a postoperative male patient with thoracolumbar kyphotic deformity. Five fixation models were established to simulate different number and location of CLs. Four loading conditions (flexion, extension, lateral bending, and axial rotation) were applied on the models. Range of motion (ROM), maximum value and distribution of stress on implants, and stress on vertebrae were compared between models. RESULTS With increased number of CLs, average ROM of instrumented segments was reduced by 2.37%, 1.89%, and 2.49% in flexion, extension, and lateral bending. ROM was reduced by 21.98% in loading axial rotation condition. With increased number of CLs, ROM tended to be limited. Peak stresses were located on rods during axial rotation, on proximal pedicle screws during flexion, and on the osteotomy site during extension and lateral bending. CLs had an effect of dispersing stress concentration. CONCLUSIONS The application of CLs enhanced the rigidity of the construct. With increased number of CLs, ROM of the construct was decreased, especially in axial rotation. CLs can also disperse the stress concentration. After comparing various CL configurations in different motion conditions, we believe that the optimal method is to place 2 CLs at the osteotomy site and the proximal segment.
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Affiliation(s)
- Tianhao Wang
- Department of Orthopaedics, Southwest Hospital, Third Military Medical University, Chongqing, China; Department of Orthopaedics, General Hospital of Chinese People's Liberation Army, Beijing, China
| | - Zhihua Cai
- School of Electromechanical Engineering, Hunan University of Science and Technology, Xiangtan, China
| | - Yongfei Zhao
- Department of Orthopaedics, General Hospital of Chinese People's Liberation Army, Beijing, China
| | - Wei Wang
- School of Electromechanical Engineering, Hunan University of Science and Technology, Xiangtan, China
| | - Guoquan Zheng
- Department of Orthopaedics, General Hospital of Chinese People's Liberation Army, Beijing, China
| | - Zheng Wang
- Department of Orthopaedics, General Hospital of Chinese People's Liberation Army, Beijing, China
| | - Yan Wang
- Department of Orthopaedics, General Hospital of Chinese People's Liberation Army, Beijing, China.
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High Infection Rates in Patients with Long-Segment Dynesys System. World Neurosurg 2018; 119:e403-e406. [PMID: 30071334 DOI: 10.1016/j.wneu.2018.07.175] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Revised: 07/19/2018] [Accepted: 07/21/2018] [Indexed: 11/22/2022]
Abstract
BACKGROUND Infection follow-up in patients stabilized with the Dynesys system. Infection rates were determined in patients who had ≥5 segments stabilized with the Dynesys system. METHODS Eighty-three patients with various etiologies were stabilized with the Dynesys system. Long-level stabilization patients were separated from the main group as a result of their high rates of infection. RESULTS Long-level stabilizations were performed in 8 of 83 patients. Five patients were determined to have infections including 4 deep infections and 1 superficial infection. In patients with deep infections, 3 of them exhibited chronic infections that lasted for approximately 2 years and the system was removed. A deep infection in 1 patient and a superficial infection in 1 patient were diagnosed after 1 month. The early-diagnosed deep infection patient was treated with wound irrigation and antibiotics. The system was not removed, and the wound was closed with daily dressing after 45 days. One superficial infection patient was only treated with daily dressing, and the infection healed within 2 weeks. The infectious agent was determined in 2 patients. Three patients in the chronic infection group underwent a surgical procedure to remove the system. Specific antibiotic treatments were administered to patients whose infectious agents were identified. The remaining patients were treated with wide-spectrum antibiotics. CONCLUSIONS We report that long-level stabilization with the Dynesys system results in a high infection rate.
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Huang S, Ji T, Guo W. [Development and current situation of reconstruction methods following total sacrectomy]. ZHONGGUO XIU FU CHONG JIAN WAI KE ZA ZHI = ZHONGGUO XIUFU CHONGJIAN WAIKE ZAZHI = CHINESE JOURNAL OF REPARATIVE AND RECONSTRUCTIVE SURGERY 2018; 32:513-518. [PMID: 29806335 DOI: 10.7507/1002-1892.201712054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Objective To review the development of the reconstruction methods following total sacrectomy, and to provide reference for finding a better reconstruction method following total sacrectomy. Methods The case reports and biomechanical and finite element studies of reconstruction following total sacrectomy at home and abroad were searched. Development and current situation were summarized. Results After developing for nearly 30 years, great progress has been made in the reconstruction concept and fixation techniques. The fixation methods can be summarized as the following three strategies: spinopelvic fixation (SPF), posterior pelvic ring fixation (PPRF), and anterior spinal column fixation (ASCF). SPF has undergone technical progress from intrapelvic rod and hook constructs to pedicle and iliac screw-rod systems. PPRF and ASCF could improve the stability of the reconstruction system. Conclusion Reconstruction following total sacrectomy remains a challenge. Reconstruction combining SPF, PPRF, and ASCF is the developmental direction to achieve mechanical stability. How to gain biological fixation to improve the long-term stability is an urgent problem to be solved.
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Affiliation(s)
- Siyi Huang
- Musculoskeletal Tumor Center, Peking University People's Hospital, Beijing, 100044, P.R.China
| | - Tao Ji
- Musculoskeletal Tumor Center, Peking University People's Hospital, Beijing, 100044, P.R.China
| | - Wei Guo
- Musculoskeletal Tumor Center, Peking University People's Hospital, Beijing, 100044,
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Peltier C, Germaneau A, Dupré JC, Hesser F, Brèque C, Rigoard P, Vendeuvre T. Biomechanical analysis of different cross-link configurations spinal instrumentation systems: a preliminary study. Comput Methods Biomech Biomed Engin 2017; 20:157-158. [DOI: 10.1080/10255842.2017.1382909] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
| | - A. Germaneau
- Institut Pprime UPR 3346, CNRS – Université de Poitiers – ENSMA, Poitiers, France
| | - J. C. Dupré
- Institut Pprime UPR 3346, CNRS – Université de Poitiers – ENSMA, Poitiers, France
| | - F. Hesser
- Institut Pprime UPR 3346, CNRS – Université de Poitiers – ENSMA, Poitiers, France
| | - C. Brèque
- Institut Pprime UPR 3346, CNRS – Université de Poitiers – ENSMA, Poitiers, France
- ABS Lab,University of Poitiers, France
| | - P. Rigoard
- CHU La Milétrie, Poitiers, France
- Institut Pprime UPR 3346, CNRS – Université de Poitiers – ENSMA, Poitiers, France
| | - T. Vendeuvre
- CHU La Milétrie, Poitiers, France
- Institut Pprime UPR 3346, CNRS – Université de Poitiers – ENSMA, Poitiers, France
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Sarigul S, Salci H, Lekesiz H, Dogan S, Ozcan R, Gorgul OS, Aksoy K. Contribution of the xenograft bone plate-screw system in lumbar transpedicular stabilization: An in vivo study in dogs. Asian J Neurosurg 2017; 12:494-500. [PMID: 28761530 PMCID: PMC5532937 DOI: 10.4103/1793-5482.185061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
OBJECTIVES Xenograft bone plate-screws (XBPSs) can be alternative tools in lumbar transpedicular stabilization (TS). The aim of this study was to show biomechanical and histopathological contribution of the XBPSs system in lumbar TS. MATERIALS AND METHODS Fifteen (n = 15) hybrid dog and ten (n = 10) L2-4 cadaveric specimens were included in the study. The dogs were separated according to surgical techniques: L3 laminectomy and bilateral facetectomy (LBF) in Group I (experimental group [EG I] (n = 5), L3 LBF plus TS with metal plate-screws (MPSs) in Group II (EG II) (n = 5), and L3 LBF plus TS with XBPSs in Group III (EG III) (n = 5). The cadaveric specimens were separated to L2-4 intact in Group I (CG I), (n = 5), and L3 LBF in Group II (CG II), (n = 5). The dogs were sacrificed at the end of 3rd month, and their L2-4 spinal segments were en bloc removed and prepared as in control groups. Flexion, extension, left-right bending, rotation, and compression tests were applied to all segments. Stiffness values were calculated and analyzed statistically. All dog segments were evaluated histopathologically. RESULTS XBPS system showed a higher average stiffness values for left bending, extension, flexion, and compression compared to MPS, but these differences were not statistically meaningful. XBPS system had superiority to the fusion formation, as well. CONCLUSIONS XBPSs provide stability and help the fusion formation, but this system does not have a biomechanical advantage over MPS system in TS.
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Affiliation(s)
- Sani Sarigul
- Department of Neurosurgery, Faculty of Medicine, Uludag University, Bursa, Turkey
| | - Hakan Salci
- Department of Surgery, Faculty of Veterinary Medicine, Uludag University, Bursa, Turkey
| | - Huseyin Lekesiz
- Department of Machines, Faculty of Engineering and Architecture, Uludag University, Bursa, Turkey
| | - Seref Dogan
- Department of Neurosurgery, Faculty of Medicine, Uludag University, Bursa, Turkey
| | - Resat Ozcan
- Department of Machines, Faculty of Engineering and Architecture, Uludag University, Bursa, Turkey
| | - Osman Sacit Gorgul
- Department of Surgery, Faculty of Veterinary Medicine, Uludag University, Bursa, Turkey
| | - Kaya Aksoy
- Department of Neurosurgery, Faculty of Medicine, Uludag University, Bursa, Turkey
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Abstract
STUDY DESIGN Biomechanical study of double-level pedicle screw constructs with or without crosslinks (CL) in an unstable model. OBJECTIVES The purpose of this study is to investigate the optimal position and orientation of the CL. SUMMARY OF BACKGROUND DATA Several reports have described biomechanical research on such CL, but no definite consensus has been reached regarding the effects. Very few studies have examined the position and orientation of the CL. The question of where and how the CL should be clinically set remains unanswered. METHODS Ten cadaveric lumbar spines (L3-L5) of boars were used and 7 models were prepared by the sequential damage and spinal instrumentation of each specimen. Bending stiffness was measured in flexion, extension, lateral bending, and axial rotation for each model using 6-axis material tester under torque of 0 to ±3 N m. Results for each configuration were compared using analysis of variance and the Turkey-Kramer test. RESULTS In flexion, extension, and lateral bending, 7 models showed similar stiffness with no significant differences. In axial rotation, stiffness increased significantly (P<0.05) in the cephalic, central, caudal, and oblique CL models in comparison with that of the no CL model, and stiffness of the horizontal 2 CL and oblique 2 CL models was significantly higher than that of cephalic, central, caudal, and oblique CL models (P<0.05). However, no significant differences in stiffness were seen between cephalic, central, and caudal CL models, between the central and oblique CL models, or between the horizontal and oblique 2 CL models. CONCLUSIONS Concomitant use of CLs significantly increased axial rotational stiffness, even though stiffness in flexion, extension, and lateral bending was not increased. In addition, stiffness in axial rotation significantly improved with the use of 2 CLs instead of a single CL, and stiffness was unchanged by position and orientation of CL.
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Behrbalk E, Uri O, Folman Y, Rickert M, Kaiser R, Boszczyk BM. Staged Correction of Severe Thoracic Kyphosis in Patients with Multilevel Osteoporotic Vertebral Compression Fractures. Global Spine J 2016; 6:710-720. [PMID: 27781192 PMCID: PMC5077718 DOI: 10.1055/s-0035-1569460] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/05/2015] [Accepted: 10/05/2015] [Indexed: 12/12/2022] Open
Abstract
Study Design Technical report. Objective Multilevel osteoporotic vertebral compression fractures may lead to considerable thoracic deformity and sagittal imbalance, which may necessitate surgical intervention. Correction of advanced thoracic kyphosis in patients with severe osteoporosis remains challenging, with a high rate of failure. This study describes a surgical technique of staged vertebral augmentation with osteotomies for the treatment of advanced thoracic kyphosis in patients with osteoporotic multilevel vertebral compression fractures. Methods Five patients (average age 62 ± 6 years) with multilevel osteoporotic vertebral compression fractures and severe symptomatic thoracic kyphosis underwent staged vertebral augmentation and surgical correction of their sagittal deformity. Clinical and radiographic outcomes were assessed retrospectively at a mean postoperative follow-up of 34 months. Results Patients' self-reported back pain decreased from 7.2 ± 0.8 to 3.0 ± 0.7 (0 to 10 numerical scale; p < 0.001). Patients' back-related disability decreased from 60 ± 10% to 29 ± 10% (0 to 100% Oswestry Disability Index; p < 0.001). Thoracic kyphosis was corrected from 89 ± 5 degrees to 40 ± 4 degrees (p < 0.001), and the sagittal vertical axis was corrected from 112 ± 83 mm to 38 ± 23 mm (p = 0.058). One patient had cement leakage without subsequent neurologic deficit. Decreased blood pressure was observed in another patient during the cement injection. No correction loss, hardware failure, or neurologic deficiency was seen in the other patients. Conclusion The surgical technique described here, despite its complexity, may offer a safe and effective method for the treatment of advanced thoracic kyphosis in patients with osteoporotic multilevel vertebral compression fractures.
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Affiliation(s)
- Eyal Behrbalk
- The Spine Unit, Hillel-Yaffe Medical Center, Hadera, Israel,Address for correspondence Dr. Eyal Behrbalk The Spine Unit, Hillel-Yaffe Medical CenterHa-Shalom Street, Hadera, 38100Israel
| | - Ofir Uri
- The Spine Unit, Hillel-Yaffe Medical Center, Hadera, Israel
| | - Yoram Folman
- The Spine Unit, Hillel-Yaffe Medical Center, Hadera, Israel
| | - Marcus Rickert
- The Centre for Spinal Studies and Surgery, Queen's Medical Centre, Nottingham, United Kingdom
| | - Radek Kaiser
- The Centre for Spinal Studies and Surgery, Queen's Medical Centre, Nottingham, United Kingdom
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Minimally Invasive Posterior Decompression Combined With Percutaneous Pedicle Screw Fixation for the Treatment of Thoracolumbar Fractures With Neurological Deficits: A Prospective Randomized Study Versus Traditional Open Posterior Surgery. Spine (Phila Pa 1976) 2016; 41 Suppl 19:B23-B29. [PMID: 27656782 DOI: 10.1097/brs.0000000000001814] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN Prospective randomized cohort study. OBJECTIVE To compare the surgical results of minimally invasive posterior decompression combined with percutaneous pedicle screws fixation (minimally invasive surgery [MIS]) and posterior open surgery (OS) for the treatment of thoracolumbar fracture with neurological deficits. SUMMARY OF BACKGROUND DATA Thoracolumbar fracture with neurological deficits usually undergoes surgical intervention. OS can achieve satisfied results, but the main disadvantage is approach-related complications. No study, however, focused on the treatment of this disease by MIS through posterior approach. METHODS Sixty consecutive cases of thoracolumbar fractures with neurological deficits were randomized into MIS group and OS group. Incision length, blood loss, postoperative drainage volume, hospitalization days, blood transfusion rate, analgesic use rate, and x-ray exposure time were used to evaluate the perioperative information and Visual Analog Scale (VAS), Japanese Orthopedics Association (JOA) score, and American Spinal Injury Association grade for patients' symptom. For radiological assessment, sagittal Cobb angle, percentage of vertebral height, and vertebral wedging angle were measured. RESULTS Fifty-nine of sixty patients were followed-up for at least 12 months. MIS group was superior in perioperative information (P < 0.05), except in the operative time (P = 0.165) and x-ray time (P = 0.000). The operative time seemed longer in MIS group, but no significant difference was found. The x-ray time was significantly higher in MIS group. The mean Visual Analog Scale and Japanese Orthopedics Association scores of the final follow-up in MIS group were better than that in OS group (P < 0.05). Patients in both group achieved a similar neurological recovery according to American Spinal Injury Association grade (P = 0.760). A broken screw was found in one patient in MIS group and a broken rod in one patient in OS group. CONCLUSION MIS group has achieved the similar effect of OS group and it can minimize the approach-related complication. It also faced with some shortages, such as larger radiation dose and longer learning curve. LEVEL OF EVIDENCE 2.
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Cahueque M, Cobar A, Zuñiga C, Caldera G. Management of burst fractures in the thoracolumbar spine. J Orthop 2016; 13:278-81. [PMID: 27408503 DOI: 10.1016/j.jor.2016.06.007] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Accepted: 06/07/2016] [Indexed: 12/14/2022] Open
Abstract
UNLABELLED The most common fractures in the spine take place in the thoracolumbar region. Currently there is no consensus regarding optimum treatment. OBJECTIVE Analyze the current medical literature available regarding treatment of compression fractures of the thoracolumbar spine. METHODS Research of current literature in medical databases. RESULTS Regarding current available literature, we found no consensus in the treatment of compression fractures in the thoracolumbar spine. CONCLUSIONS Burst fractures of the thoracolumbar junction is a very common condition, treatment of each patient must be individualized. Conservative treatment is recommended for stable fractures without neurological compromise and less than 35° of kyphosis.
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Affiliation(s)
- Mario Cahueque
- Orthopedic Surgeon, Centro Medico Nacional de Occidente, Guadalajara, Mexico
| | - Andrés Cobar
- Orthopedic Surgeon, Centro Medico Nacional de Occidente, Guadalajara, Mexico
| | - Carlos Zuñiga
- Neurosurgeon, Centro Medico Nacional de Occidente, Guadalajara, Mexico
| | - Gustavo Caldera
- Orthopedic and Spine Surgeon, Orthopedics, Centro Medico Nacional de Occidente, Guadalajara, Mexico
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25
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Goldstein CL, Brodke DS, Choma TJ. Surgical Management of Spinal Conditions in the Elderly Osteoporotic Spine. Neurosurgery 2016; 77 Suppl 4:S98-107. [PMID: 26378363 DOI: 10.1227/neu.0000000000000948] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Osteoporosis, the most common form of metabolic bone disease, leads to alterations in bone structure and density that have been shown to compromise the strength of spinal instrumentation. In addition, osteoporosis may contribute to high rates of fracture and instrumentation failure after long posterior spinal fusions, resulting in proximal junctional kyphosis and recurrent spinal deformity. As increasing numbers of elderly patients present for surgical intervention for degenerative and traumatic spinal pathologies, current and future generations of spine surgeons will increasingly be faced with the challenge of obtaining adequate fixation in osteoporotic bone. The purpose of this review is to familiarize the reader with the impact of osteoporosis on spinal instrumentation, the broad variety of techniques that have been developed for addressing these issues, and the biomechanical and clinical evidence in support of the use of these techniques.
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Affiliation(s)
- Christina L Goldstein
- *University of Missouri, Department of Orthopaedic Surgery, Columbia, Missouri; ‡Department of Orthopaedic Surgery, University of Utah, Salt Lake City, Utah
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VCELAK JOSEF, TICHÝ PETR, BOUDA TOMÁŠ, CHOMIAK JIŘÍ, TÓTH LADISLAV. PEDICLE SCREW CONVERGENCE IMPACT ON THE STABILITY OF TRANSPEDICULAR FIXATION SPINE MODEL IN CYCLIC LOADING: BIOMECHANICAL STUDY. J MECH MED BIOL 2015. [DOI: 10.1142/s0219519415500785] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The principle of this study is experimental measurement and description of behavior of transpedicular fixation during cyclic loading due to convergence of screw insertion. Investigations were made of three configurations of assemblies of posterior stabliization with converging screws at 0°, 20° and 40°. The experiment was inspired ASTM Standard F1717 and modified to minimize the effect of other parameters. The MTS 858.2 Mini Bionix testing system was used during the experiment, in conjunction with the Interface 1010ACK load cell. Data processing and analysis were carried out by Matlab R 20102b, MathWorks. The probed assemblies were cyclically loaded until structural failure occurred, always at the screwbone (or PUR block) interface, i.e., the "windshield wiper" effect. The measurement results show that while the rigidity of the assembly increases with increased convergence of transpedicular screws, they also indicate an increased initial rate of assembly damage accumulation, together with assembly failure during a reduced number of cyclic loading cycles. The mechanical behavioral study of transpedicular fixation is limited by the conditions of simplification of interpretation of complex movements and spinal pathophysiology in the attempt to minimize the effect of other parameters and exaggerated measurements.
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Affiliation(s)
- JOSEF VCELAK
- Orthopaedic Clinic, 1st Medical Faculty, Charles University, Prague, Czech Republic
| | - PETR TICHÝ
- Orthopaedic Clinic, 1st Medical Faculty, Charles University, Prague, Czech Republic
| | - TOMÁŠ BOUDA
- Orthopaedic Clinic, 1st Medical Faculty, Charles University, Prague, Czech Republic
| | - JIŘÍ CHOMIAK
- Orthopaedic Clinic, 1st Medical Faculty, Charles University, Prague, Czech Republic
| | - LADISLAV TÓTH
- Orthopaedic Clinic, 1st Medical Faculty, Charles University, Prague, Czech Republic
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Matsukawa K, Yato Y, Imabayashi H, Hosogane N, Asazuma T, Nemoto K. Biomechanical evaluation of the fixation strength of lumbar pedicle screws using cortical bone trajectory: a finite element study. J Neurosurg Spine 2015; 23:471-8. [DOI: 10.3171/2015.1.spine141103] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECT
Cortical bone trajectory (CBT) maximizes thread contact with the cortical bone surface and provides increased fixation strength. Even though the superior stability of axial screw fixation has been demonstrated, little is known about the biomechanical stiffness against multidirectional loading or its characteristics within a unit construct. The purpose of the present study was to quantitatively evaluate the anchorage performance of CBT by the finite element (FE) method.
METHODS
Thirty FE models of L-4 vertebrae from human spines (mean age [± SD] 60.9 ± 18.7 years, 14 men and 16 women) were computationally created and pedicle screws were placed using the traditional trajectory (TT) and CBT. The TT screw was 6.5 mm in diameter and 40 mm in length, and the CBT screw was 5.5 mm in diameter and 35 mm in length. To make a valid comparison, the same shape of screw was inserted into the same pedicle in each subject. First, the fixation strength of a single pedicle screw was compared by axial pullout and multidirectional loading tests. Next, vertebral fixation strength within a construct was examined by simulating the motions of flexion, extension, lateral bending, and axial rotation.
RESULTS
CBT demonstrated a 26.4% greater mean pullout strength (POS; p = 0.003) than TT, and also showed a mean 27.8% stronger stiffness (p < 0.05) during cephalocaudal loading and 140.2% stronger stiffness (p < 0.001) during mediolateral loading. The CBT construct had superior resistance to flexion and extension loading and inferior resistance to lateral bending and axial rotation. The vertebral fixation strength of the construct was significantly correlated with bone mineral density of the femoral neck and the POS of a single screw.
CONCLUSIONS
CBT demonstrated superior fixation strength for each individual screw and sufficient stiffness in flexion and extension within a construct. The TT construct was superior to the CBT construct during lateral bending and axial rotation.
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Affiliation(s)
- Keitaro Matsukawa
- 1Department of Orthopaedic Surgery, National Defense Medical College, Tokorozawa, Saitama; and
| | - Yoshiyuki Yato
- 2Department of Orthopaedic Surgery, National Hospital Organization, Murayama Medical Center, Musashimurayama, Tokyo, Japan
| | - Hideaki Imabayashi
- 1Department of Orthopaedic Surgery, National Defense Medical College, Tokorozawa, Saitama; and
| | - Naobumi Hosogane
- 1Department of Orthopaedic Surgery, National Defense Medical College, Tokorozawa, Saitama; and
| | - Takashi Asazuma
- 2Department of Orthopaedic Surgery, National Hospital Organization, Murayama Medical Center, Musashimurayama, Tokyo, Japan
| | - Koichi Nemoto
- 1Department of Orthopaedic Surgery, National Defense Medical College, Tokorozawa, Saitama; and
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Biomechanical stability of transverse connectors in the setting of a thoracic pedicle subtraction osteotomy. Spine J 2015; 15:1629-35. [PMID: 25771755 DOI: 10.1016/j.spinee.2015.03.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Revised: 12/19/2014] [Accepted: 03/07/2015] [Indexed: 02/03/2023]
Abstract
BACKGROUND CONTEXT Transverse connectors (TCs) are often used to improve the rigidity of posterior spinal instrumentation as previous investigations have suggested that TCs enhance torsional rigidity in long-segment thoracic constructs. Posterior osteotomies, such as pedicle subtraction osteotomy (PSO), are used in severe thoracic deformities and provide a significant amount of correction; as a consequence, however, PSOs also induce three-column spinal instability. In theory, augmentation of longitudinal constructs with TC after a thoracic PSO may provide additional rigidity, but the concept has not been previously evaluated. PURPOSE To evaluate the biomechanical contribution of TC to the rigidity of a long-segment pedicle screw-rod construct after a thoracic PSO. STUDY DESIGN An in vitro fresh-frozen human cadaveric biomechanical analysis. METHODS Seven human cadaveric thoracic spines were prepared and instrumented from T4-T10 with bilateral pedicle screws/rods and a PSO was performed at T7. Intact range of motion (ROM) testing was performed with nondestructive loading and analyzed by loading modality (axial rotation [AR], flexion/extension [FE], and lateral bending [LB]). Range of motion analysis was performed in the unaugmented construct, the construct augmented with one TC, and the construct augmented with two TCs. RESULTS After PSO and an unaugmented longitudinal pedicle screw-rod construct, T4-T10 (overall construct) and T6-T8 (PSO site) ROMs were significantly reduced in all planes of motion compared with intact condition (AR: 11.8° vs. 31.7°; FE: 2.4° vs. 12.3°; 3.4° vs. 17.9°, respectively, p<.05). Augmentation of longitudinal construct with either one or two TCs did not significantly increase construct rigidity in FE or LB compared with the unaugmented construct (p>.05). In contrast, during AR, global ROM was significantly reduced by 43% and 48% at T6-T8 (1.7° and 1.2° vs. 2.38°, respectively) after addition of one and two TCs (p<.05), respectively. One TC did not significantly reduce torsional ROM from the intact state. CONCLUSIONS Two TCs significantly improved torsional rigidity of the entire construct and at the PSO site, with no differences in rigidity for FE and LB or with the addition of only one TC. In the setting of a PSO and long-segment pedicle screw-rod construct, augmentation with at least two TCs should be considered to improve torsional rigidity.
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Garg S, Niswander C, Pan Z, Erickson M. Cross-Links Do Not Improve Clinical or Radiographic Outcomes of Posterior Spinal Fusion With Pedicle Screws in Adolescent Idiopathic Scoliosis: A Multicenter Cohort Study. Spine Deform 2015; 3:338-344. [PMID: 27927479 DOI: 10.1016/j.jspd.2014.12.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Revised: 11/17/2014] [Accepted: 12/14/2014] [Indexed: 11/25/2022]
Abstract
STUDY DESIGN Retrospective, comparative analysis. OBJECTIVES Comparative analysis was performed to determine the differences, if any, between adolescent idiopathic scoliosis (AIS) patients who underwent posterior spinal fusion (PSF) with and without cross-links. SUMMARY OF BACKGROUND DATA Cross-links are frequently used during PSF for AIS. It is unclear whether they provide any advantage for patients with all-pedicle screw constructs. METHODS A prospectively collected multicenter database of patients with AIS undergoing spinal fusion was retrospectively queried. Study inclusion criteria were primary PSF with all-pedicle screw fixation (greater than 90% fixation points) and minimum 2 years' follow-up. Collected data included demographics, radiographic measures, complications, Scoliosis Research Society-22r and Spinal Appearance Questionnaire (SAQ) scores. RESULTS A total of 500 patients were included (377 cross-link and 123 non-cross-link). Age, body mass index, gender, and preoperative major Cobb angle were not different between groups. Except for a slightly decreased lumbar Cobb angle (2.7°) in the cross-link group, no other radiographic measures were different at follow-up. Complications were not significantly different between groups: 21 of 377 (6%) crosslink and 9 of 123 (7%) non-cross-link. Infection occurred in 1 patient in the cross-link group and none in the non-cross link group. Reoperation occurred in 4 patients, all with cross-links (3 for implant removal and 1 for distal adding-on). Scoliosis Research Society-22r scores, total and individual domains, improved by a similar amount in both groups. At follow-up, parent and patient SAQ appearance scores were not significantly different. The SAQ expectations domain scores were similar for all visits and improved for both patients and parents. CONCLUSIONS There do not appear to be significant clinical or radiographic outcome differences in patients with AIS undergoing PSF based on the use of cross-links at 2-year follow-up. Surgeons should consider eliminating cross-links in patients with AIS who have PSF with all-pedicle screw constructs. This may have substantial cost savings without affecting patient outcome.
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Affiliation(s)
- Sumeet Garg
- Children's Hospital Colorado Orthopedics Institute, University of Colorado, 13123 East 16th Avenue, Box 060, Aurora, CO 80045, USA.
| | - Cameron Niswander
- Children's Hospital Colorado Orthopedics Institute, University of Colorado, 13123 East 16th Avenue, Box 060, Aurora, CO 80045, USA
| | - Zhaoxing Pan
- Children's Hospital Colorado Orthopedics Institute, University of Colorado, 13123 East 16th Avenue, Box 060, Aurora, CO 80045, USA
| | - Mark Erickson
- Children's Hospital Colorado Orthopedics Institute, University of Colorado, 13123 East 16th Avenue, Box 060, Aurora, CO 80045, USA
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Radcliff KE, Hussain MM, Moldavsky M, Klocke NF, Vaccaro A, Albert TJ, Khalil S, Bucklen BS. Stabilization of the craniocervical junction after an internal dislocation injury: an in vitro study. Spine J 2015; 15:1070-6. [PMID: 25681231 DOI: 10.1016/j.spinee.2015.02.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Revised: 12/22/2014] [Accepted: 02/01/2015] [Indexed: 02/03/2023]
Abstract
BACKGROUND CONTEXT Reconstructive surgeries at the occipitocervical (OC) junction have been studied in treating degenerative conditions. There is a paucity of data for optimal fixation for a traumatically unstable OC joint. In clinical OC dislocations, segmental fixation may be impossible because of vertebral artery injury or fracture. Segmental fixation of the occiput, C1, and C2 demonstrated maximum biomechanical stability in fixation of an unstable craniocervical dislocation. A biomechanical study comparing various points of cervical posterior screw fixation after recreating traumatic injury would illuminate relative advantages between the various techniques. PURPOSE To determine the rigidity lost, if any, of segmental C0-C2 posterior screw fixation versus fixation skipping C1 at the OC junction, with or without a cross-connector. STUDY DESIGN This study is a cadaveric biomechanical investigation. METHODS Intervertebral motions and translations were recorded in seven specimens under conditions in the following order: intact, OC dislocation model with complete disruption of the cruciate ligaments, alar ligaments, and occipitoatlantal/atlantoaxial capsules (injury), segmental posterior fixation (SPF) with posterior instrumentation (ELLIPSE; Globus Medical, Inc., Audubon, PA, USA) at occiput, C1, and C2 levels, endpoint fixation (EPF) with posterior instrumentation at occiput and C1 level skipping C1, and endpoint fixation with a cross-connector (EPFC). Motion was applied through a custom spine simulator with a pure moment load of 2.5 Nm and measured with motion capture markers attached to occiput (C0), anterior C1 ring, and C2. Flexion-extension (FE), lateral bending (LB), axial rotation (AR), and cranial-caudal (CC) motions were recorded in terms of C0-C2. Results were reported as a percentage of injured motion (injury=100%), unless otherwise stated. RESULTS The injury significantly increased the motion to 165%, 263%, and 130%, during FE, LB, and AR, respectively, of intact. The CC translations increased to 164%, 254%, and 121% during FE, LB, AR, respectively, of intact. Segmental posterior fixation significantly reduced motion to 7%, 8%, and 1%, during FE, LB, and AR, respectively, of injury. Endpoint fixation significantly increased motion in FE, resulting in 12%, 6%, and 4% during FE, LB, and AR, respectively, of injury when compared with SPF. The EPFC construct decreased the motion compared with its counterpart to 8.6%, 5.7%, and 3.2% during FE, LB, and AR, respectively. CONCLUSIONS All fixation constructs significantly reduced motion in all loading modes and CC translations, compared with intact and injury. The construct with the greatest stability against craniocervical dislocation included SPF with instrumentation at the occiput, C1, and C2. By skipping C1 using the EPF, FE and cephalad-caudal translations significantly increased compared with posterior fixation at every level. The addition of a cross-connector increased the stability but was not statistically significant.
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Affiliation(s)
- Kris E Radcliff
- Rothman Institute, 2500 English Creek Ave., Building 1300, Egg Harbor Township, NJ 08234, USA
| | - Mir M Hussain
- MERC, Globus Medical, Inc., 2560 General Armistead Ave., Audubon, PA 19403, USA.
| | - Mark Moldavsky
- MERC, Globus Medical, Inc., 2560 General Armistead Ave., Audubon, PA 19403, USA
| | - Noelle F Klocke
- MERC, Globus Medical, Inc., 2560 General Armistead Ave., Audubon, PA 19403, USA
| | - Alexander Vaccaro
- Rothman Institute, 925 Chestnut St, 5th Floor, Philadelphia, PA 19107, USA
| | - Todd J Albert
- Rothman Institute, 925 Chestnut St, 5th Floor, Philadelphia, PA 19107, USA
| | - Saif Khalil
- MERC, Globus Medical, Inc., 2560 General Armistead Ave., Audubon, PA 19403, USA
| | - Brandon S Bucklen
- MERC, Globus Medical, Inc., 2560 General Armistead Ave., Audubon, PA 19403, USA
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Biomechanical comparison of an interspinous fusion device and bilateral pedicle screw system as additional fixation for lateral lumbar interbody fusion. Clin Biomech (Bristol, Avon) 2015; 30:205-10. [PMID: 25577548 DOI: 10.1016/j.clinbiomech.2014.10.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Revised: 10/08/2014] [Accepted: 10/08/2014] [Indexed: 02/07/2023]
Abstract
BACKGROUND This investigation compares an interspinous fusion device with posterior pedicle screw system in a lateral lumbar interbody lumbar fusion. METHODS We biomechanically tested six cadaveric lumbar segments (L1-L2) under an axial preload of 50N and torque of 5Nm in flexion-extension, lateral bending and axial rotation directions. We quantified range of motion, neutral zone/elastic zone stiffness in the following conditions: intact, lateral discectomy, lateral cage, cage with interspinous fusion, and cage with pedicle screws. FINDINGS A complete lateral discectomy and annulectomy increased motion in all directions compared to all other conditions. The lateral cage reduced motion in lateral bending and flexion/extension with respect to the intact and discectomy conditions, but had minimal effect on extension stiffness. Posterior instrumentation reduced motion, excluding interspinous augmentation in axial rotation with respect to the cage condition. Interspinous fusion significantly increased flexion and extension stiffness, while pedicle screws increased flexion/extension and lateral bending stiffness, with respect to the cage condition. Both posterior augmentations performed equivalently throughout the tests except in lateral bending stiffness where pedicle screws were stiffer in the neutral zone. INTERPRETATION A lateral discectomy and annulectomy generates immediate instability. Stand-alone lateral cages restore a limited amount of immediate stability, but posterior supplemental fixation increases stability. Both augmentations are similar in a single level lateral fusion in-vitro model, but pedicle screws are more equipped for coronal stability. An interspinous fusion is a less invasive alternative than pedicle screws and is potentially a conservative option for various interbody cage scenarios.
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Rahmathulla G, Deen HG. Spine fusion cross-link causing delayed dural erosion and CSF leak: case report. J Neurosurg Spine 2015; 22:439-43. [PMID: 25635637 DOI: 10.3171/2014.9.spine14244] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The past 2 decades have seen a considerable increase in the number of lumbar spinal fusion surgeries. To enhance spinal stabilization and fusion, make the construct resistant to or stiffer for axial stress loading, lateral bending, and torsional stresses, cross-links and connectors were designed and included in a rod-screw construct. The authors present the case of a 49-year-old woman who presented 11 years after undergoing an L4-5 decompression and fusion in which a pedicle screw-rod construct with an integrated cross-link was designed to attach onto the pedicle screws. The patient's response at the time to the initial surgery was excellent; however, at the time of presentation 11 years later, she had significant postural headaches, severe neurogenic claudication, and radiculopathy. Imaging revealed canal compression across the instrumented levels and a possible thickened adherent filum terminale. Reexploration of the level revealed a large erosive dural defect with a CSF leak, spinal canal compression, and a thickened filum at the level of the cross-link. To the author's knowledge, such complications have not been reported in literature. The authors discuss this rare complication of spinal fusion and the need to avoid dural compression when cross-links are used.
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Does addition of crosslink to pedicle-screw-based instrumentation impact the development of the spinal canal in children younger than 5 years of age? EUROPEAN SPINE JOURNAL : OFFICIAL PUBLICATION OF THE EUROPEAN SPINE SOCIETY, THE EUROPEAN SPINAL DEFORMITY SOCIETY, AND THE EUROPEAN SECTION OF THE CERVICAL SPINE RESEARCH SOCIETY 2014; 24:1391-8. [DOI: 10.1007/s00586-014-3727-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2014] [Revised: 12/14/2014] [Accepted: 12/14/2014] [Indexed: 11/30/2022]
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Calvert GC, Lawrence BD, Abtahi AM, Bachus KN, Brodke DS. Cortical screws used to rescue failed lumbar pedicle screw construct: a biomechanical analysis. J Neurosurg Spine 2014; 22:166-72. [PMID: 25478820 DOI: 10.3171/2014.10.spine14371] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
OBJECT Cortical trajectory screw constructs, developed as an alternative to pedicle screw fixation for the lumbar spine, have similar in vitro biomechanics. The possibility of one screw path having the ability to rescue the other in a revision scenario holds promise but has not been evaluated. The objective in this study was to investigate the biomechanical properties of traditional pedicle screws and cortical trajectory screws when each was used to rescue the other in the setting of revision. METHODS Ten fresh-frozen human lumbar spines were instrumented at L3-4, 5 with cortical trajectory screws and 5 with pedicle screws. Construct stiffness was recorded in flexion/extension, lateral bending, and axial rotation. The L-3 screw pullout strength was tested to failure for each specimen and salvaged with screws of the opposite trajectory. Mechanical stiffness was again recorded. The hybrid rescue trajectory screws at L-3 were then tested to failure. RESULTS Cortical screws, when used in a rescue construct, provided stiffness in flexion/extension and axial rotation similar to that provided by the initial pedicle screw construct prior to failure. The rescue pedicle screws provided stiffness similar to that provided by the primary cortical screw construct in flexion/extension, lateral bending, and axial rotation. In pullout testing, cortical rescue screws retained 60% of the original pedicle screw pullout strength, whereas pedicle rescue screws retained 65% of the original cortical screw pullout strength. CONCLUSIONS Cortical trajectory screws, previously studied as a primary mode of fixation, may also be used as a rescue option in the setting of a failed or compromised pedicle screw construct in the lumbar spine. Likewise, a standard pedicle screw construct may rescue a compromised cortical screw track. Cortical and pedicle screws each retain adequate construct stiffness and pullout strength when used for revision at the same level.
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Affiliation(s)
- Graham C Calvert
- Department of Orthopaedics, Orthopaedic Bioengineering Laboratory, University of Utah, Salt Lake City, Utah
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Utino ET, Bergamaschi JPM, Pellegrino LAN, Umeta RSG, Caffaro MFS, Meves R, Avanzi O. Radiographic evaluation of the use of transverse traction device in vertebral arthrodesis for degenerative diseases. COLUNA/COLUMNA 2014. [DOI: 10.1590/s1808-18512014130100241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
OBJECTIVE: Perform radiographic analysis of the use of Transverse Traction Device (DTT) with respect to fusion rate in patients submitted to vertebral arthrodesis for degenerative lumbar diseases. METHODS: We selected x-ray images on anteroposterior, lateral and oblique views and with maximum flexion and extension dynamics of 23 patients submitted to posterolateral arthrodesis of the lumbar spine with a minimum follow-up period of six months. The images were evaluated and classified by the Linovitz's system by two spine surgeons. RESULTS: We evaluated the radiographs of 23 patients after the minimum postoperative period of 6 months and of these, 11 have used DTT. With regard to the consolidation rate, seven patients (63.6%) in the group of DTT were classified as fusion as well as six patients (50%) who were not submitted to the treatment. There was no statistical difference between the groups regarding the consolidation rate. CONCLUSION: The use of transverse traction device in this study showed no significant difference in the rate of consolidation in radiographic evaluation. Studies on the effective participation of this device in the stability of pedicle fixation systems are still lacking in the literature.
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Effectiveness of cross-linking posterior segmental instrumentation in adolescent idiopathic scoliosis: a 2-year follow-up comparative study. Spine J 2013; 13:1485-92. [PMID: 23800823 DOI: 10.1016/j.spinee.2013.05.022] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2012] [Revised: 02/08/2013] [Accepted: 05/04/2013] [Indexed: 02/03/2023]
Abstract
BACKGROUND CONTEXT Surgeons continue to debate the need for a cross-link (CL) in posterior spinal instrumentation constructs with segmental pedicle screws in adolescent idiopathic scoliosis (AIS). Advantage of CLs is increased stiffness of the construct, and disadvantages include added expense and risk of late operative-site pain and pseudarthrosis. PURPOSE To compare the effectiveness of using CLs versus using no cross-links (NCLs) in posterior segmental instrumentation in AIS. STUDY DESIGN Retrospective comparative study, level of evidence 3. PATIENT SAMPLE Seventy-five AIS patients less than 21 years of age, who underwent posterior spinal instrumentation with segmental pedicle screws (25 with CLs and 50 with NCLs) at a single institution with 2-year follow-up, are described. OUTCOME MEASURES Physiologic measures include imaging: thoracic and lumbar Cobb angles, correction rate, apical vertebral translation (AVT), and apical vertebral rotation (AVR); self-report measures include Scoliosis Research Society (SRS) domain outcome scores. METHODS Preoperative (pre-op) and postoperative first erect, 1-year, and 2-year follow-up radiographs were measured. Instrumentation-related complications and normalized SRS scores were recorded. Independent sample t test, χ(2) test, and repeated-measures analysis of variance were used for analyses. RESULTS The average age at surgery was 14 years, the mean pre-op Cobb angle was 57°, and the mean number of levels fused was 10.9. The groups were similar preoperatively with respect to age, sex, Lenke curve, Cobb angle, AVT, and Risser grade and were similar intraoperatively for levels fused and anchor density. There was no difference in AVR, Cobb angle, correction rate, or AVT between the groups (p>.05). Complications included one wound infection in the CL group and one painful scar in the NCL group. There were no differences in SRS domain scores. CONCLUSION We observed no differences in maintenance of correction, SRS scores, and complications with or without cross-linking posterior segmental instrumentation in AIS patients over 2-year follow-up. Further follow-up is necessary.
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Alizadeh M, Kadir MRA, Fadhli MM, Fallahiarezoodar A, Azmi B, Murali MR, Kamarul T. The use of X-shaped cross-link in posterior spinal constructs improves stability in thoracolumbar burst fracture: a finite element analysis. J Orthop Res 2013; 31:1447-54. [PMID: 23640802 DOI: 10.1002/jor.22376] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2012] [Accepted: 04/01/2013] [Indexed: 02/04/2023]
Abstract
Posterior instrumentation is a common fixation method used to treat thoracolumbar burst fractures. However, the role of different cross-link configurations in improving fixation stability in these fractures has not been established. A 3D finite element model of T11-L3 was used to investigate the biomechanical behavior of short (2 level) and long (4 level) segmental spine pedicle screw fixation with various cross-links to treat a hypothetical L1 vertebra burst fracture. Three types of cross-link configurations with an applied moment of 7.5 Nm and 200 N axial force were evaluated. The long construct was stiffer than the short construct irrespective of whether the cross-links were used (p < 0.05). The short constructs showed no significant differences between the cross-link configurations. The XL cross-link provided the highest stiffness and was 14.9% stiffer than the one without a cross-link. The long construct resulted in reduced stress to the adjacent vertebral bodies and screw necks, with 66.7% reduction in bending stress on L2 when the XL cross-link was used. Thus, the stability for L1 burst fracture fixation was best achieved by using long segmental posterior instrumentation constructs and an XL cross-link configuration. Cross-links did not improved stability when a short structure was used.
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Affiliation(s)
- Mina Alizadeh
- Medical Implant Technology Group (MEDITEG), Faculty of Biosciences and Medical Engineering, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor, Malaysia
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Abstract
STUDY DESIGN Retrospective study. OBJECTIVE To assess critically if cross-links are necessary adjuvants in posterior spinal constructs. SUMMARY OF BACKGROUND DATA Although numerous biomechanical studies are available in the literature, there has been no clinical study that has evaluated the need for cross-links in clinical situations. METHODS The spinal constructs of patients of varied etiology who underwent surgery between July 2007 and July 2011 without the usage of cross-links were evaluated. The immediate postoperative erect radiographs were compared with the erect radiographs at the last follow-up by 2 independent observers (spine fellows not involved in the management of the patients) critically for any rotational instability using the Nash-Moe technique of assessment of vertebral rotation as well as for any "parallelogram effect." The intraobserver and interobserver reliability was analyzed. RESULTS There were 208 cases included in the study during the study period that satisfied the criteria. The total number of motion segments fused was 707 ranging from 1 to 15 involving various etiologies. The average follow-up was 15 months (12-36 mo). Barring one patient with a thoracolumbar fracture with rotational instability (AO [Arbeitsgemeinschaft für Osteosynthesefragen] type C) who had undergone a short-segment fixation, none of the cases demonstrated any rotational instability in the follow-up radiographs. Interestingly, the rotational instability (parallelogram effect) in that patient got corrected spontaneously once anterior reconstruction was performed. The intraobserver reliability was 100% and the interobserver reliability was 92.83%. This variability was in assessing the grade of vertebral rotation only; none of the levels had a change in rotation irrespective of variation in grade assessment in the final postoperative radiograph. CONCLUSION This study concludes that use of cross-links in clinical practice may be avoidable. The derivations from biomechanical studies do not translate into clinical advantages. Eliminating the usage of cross-links reduces the operative time as well as the overall total hospital costs (a single cross-link may cost anywhere between $1500 and $2000 and surgeons tend to use single or multiple cross-links). Additionally, prominence of implants, corrosion, infection, implant failure, and pseudarthrosis are the other complications attributed to cross-links in the literature that can be eliminated by preventing their incorporation in spinal constructs. LEVEL OF EVIDENCE N/A.
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Kanayama M. Sagittal plane correction in pedicle subtraction osteotomy using the Xia 3 SUK Direct Vertebral Rotation System: technical note. J Neurosurg Spine 2013; 19:507-14. [PMID: 23930717 DOI: 10.3171/2013.7.spine121162] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The Xia 3 SUK Direct Vertebral Rotation (DVR) System was developed for performing the vertebral derotation maneuver in scoliosis surgery. The author applied this device to sagittal plane correction in pedicle subtraction osteotomy for adult spinal deformity. The surgical procedure included 1) preparing secure proximal and distal foundations for correction using mutisegmental pedicle screw-rod fixation (to avoid stress concentration to a specific screw-bone interface), 2) decancellating only the posterior two-thirds of the vertebral column, 3) providing supplemental interbody fusion above and below the osteotomy site (the anterior one-third of the vertebral column and interbody cages serve as an anterior column support and a pivot of correction), 4) closing the osteotomy by gradual approximation of SUK tubes secured to the proximal- and distal-most screw heads, and 5) connecting rods between the proximal and distal screw-rod constructs. Eight consecutive patients with fixed sagittal imbalance were treated using this surgical procedure. No patient required distal fixation points extending to the sacrum and/or pelvis. The sagittal plane correction was 43°. The mean anterior deviation of the C-7 plumb line was improved from 12.7 cm to 4.0 cm immediately after surgery, and it was 6.0 cm at the final follow-up. A pedicle subtraction osteotomy using the Xia 3 SUK DVR System ensures a safe and secure sagittal plane correction in adult spinal deformity.
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Comparative analysis of posterior fusion constructs as treatments for middle and posterior column injuries: an in vitro biomechanical investigation. Clin Biomech (Bristol, Avon) 2013; 28:483-9. [PMID: 23707137 DOI: 10.1016/j.clinbiomech.2013.05.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2013] [Revised: 04/30/2013] [Accepted: 05/01/2013] [Indexed: 02/07/2023]
Abstract
BACKGROUND Titanium pedicle screw-rod instrumentation is considered a standard treatment for spinal instability; however, the advantages of cobalt-chromium over titanium is generating interest in orthopedic practice. The aim of this study was to compare titanium versus cobalt-chromium rods in posterior fusion through in vitro biomechanical testing. METHODS Posterior and middle column injuries were simulated at L3-L5 in six cadaveric L1-S1 human spines and different pedicle screw constructs were implanted. Specimens were subjected to flexibility tests and range of motion, intradiscal pressure and axial rotation energy loss were statistically compared among five conditions: intact, titanium rods (with and without transverse connectors) and cobalt-chromium rods (with and without transverse connectors). FINDINGS All fusion constructs significantly (P<0.01) decreased range of motion in flexion-extension and lateral bending with respect to intact, but no significant differences (P>0.05) were observed in axial rotation among all conditions. Intradiscal pressure significantly increased (P≤0.01) after fusion, except for the cobalt-chrome conditions in extension (P≥0.06), and no significant differences (P>0.99) were found among fixation constructs. In terms of energy loss, differences became significant P≤0.05 between the cobalt-chrome with transverse connector condition with respect to the cobalt-chrome and titanium conditions. INTERPRETATION There is not enough evidence to support that the cobalt-chrome rods performed biomechanically different than the titanium rods. The inclusion of the transverse connector only increased stability for the cobalt-chromium construct in axial rotation.
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Biomechanics of lumbar cortical screw-rod fixation versus pedicle screw-rod fixation with and without interbody support. Spine (Phila Pa 1976) 2013; 38:635-41. [PMID: 23104197 DOI: 10.1097/brs.0b013e318279a95e] [Citation(s) in RCA: 140] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN Seven different combinations of posterior screw fixation, with or without interbody support, were compared in vitro using nondestructive flexibility tests. OBJECTIVE To study the biomechanical behavior of a new cortical screw (CS) fixation construct relative to the traditional pedicle screw (PS) construct. SUMMARY OF BACKGROUND DATA The CS is an alternative to the PS for posterior fixation of the lumbar spine. The CS trajectory is more sagittally and cranially oriented than the PS, being anchored in the pars interarticularis. Like PS fixation, CS fixation uses interconnecting rods fastened with top-locking connectors. Stability after bilateral CS fixation was compared with stability after bilateral PS fixation in the setting of intact disc and with direct lateral interbody fixation (DLIF) or transforaminal lateral interbody fixation (TLIF) support. METHODS Standard nondestructive flexibility tests were performed in cadaveric lumbar specimens, allowing non-paired comparisons of specific conditions from 28 specimens (4 groups of 7) within a larger experiment of multiple hardware configurations. Condition tested and group from which results originated were as follows: (1) intact (all groups); (2) with L3-L4 bilateral PS-rods (group 1); (3) with bilateral CS-rods (group 2); (4) with DLIF (group 3); (5) with DLIF + CS-rods (group 4); (6) with DLIF + PS-rods (group 3); (7) with TLIF + CS-rods (group 2), and (8) with TLIF + PS-rods (group 2). To assess spinal stability, the mean range of motion, lax zone, and stiff zone at L3-L4 were compared during flexion-extension, lateral bending, and axial rotation. RESULTS With intact disc, stability was equivalent after PS-rod and CS-rod fixation, except that PS-rod fixation was stiffer during axial rotation. With DLIF support, there was no significant difference in stability between PS-rod and CS-rod fixation. With TLIF support, PS-rod fixation was stiffer than CS-rod fixation during lateral bending. CONCLUSION Bilateral CS-rod fixation provided about the same stability in cadaveric specimens as PS-rod fixation regardless of the presence of interbody, TLIF, or DLIF support.
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Abstract
STUDY DESIGN A 10-point questionnaire was constructed to identify the philosophy of surgeons on various aspects of scoliosis surgery, such as choice of implant, bone graft, autologous blood transfusion, cord monitoring, and computer-assisted surgery. Comparisons were then made with recommendations published in the spinal literature. OBJECTIVE To determine certain aspects of the current practice of scoliosis surgery in the United Kingdom. SUMMARY OF BACKGROUND DATA Guidelines for good clinical practice in spinal deformity surgery are available in the United Kingdom but do not cover a number of controversial issues. METHODS Consultants and fellows attended the 2009 British Scoliosis Society meeting. Fifty questionnaires were completed by 45 consultants and 5 fellows. RESULTS All pedicle screw constructs favored by 25 of 50, hybrid 24 of 50 (1 undecided). Posterior construct of fewer than 10 levels, 20 of 50 would not cross-link, 11 of 50 used 1, and 19 of 20 used 2 or more. More than 10 levels 17 of 50 considered cross-links unnecessary, 4 of 50 used 1 and 29 of 50 used 2 or more. Eighty-eight percent preferred titanium alloy implants, whereas others used a mixture of stainless steel and cobalt chrome. When using bone graft, respondents used bone substitutes (24), iliac crest graft (14), allograft (12) and demineralized bone matrix (9) in addition to local bone. Ten of 50 would use recombinant bone morphogenetic protein (3 for revision cases only). Thirty-nine of 50 routinely used intraoperative cell salvage and 4 of 50 never used autologous blood. All used cord monitoring: sensory (19 of 50), motor (2 of 50), and combined (29 of 50). None used computer-aided surgery. Twenty-six operated alone, 12 operated in pairs, and 12 varied depending on type of case. CONCLUSION This survey shows interesting variations in scoliosis surgery in the United Kingdom. It may reflect the conflicting evidence in the literature.
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Goldschlager T, Leach JCD, Williamson OD, Malham GM. Oblique axis body fracture--pitfalls in management. Injury 2012; 43:505-8. [PMID: 20466369 DOI: 10.1016/j.injury.2010.04.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2009] [Accepted: 04/12/2010] [Indexed: 02/02/2023]
Abstract
BACKGROUND Transverse fractures through the body of the axis, rather than at the base of the odontoid are uncommon and management with an external orthosis is usually recommended. Oblique fractures through the body of the axis accompanying a hangman's fracture have not been reported and are not described as part of any classification system. Such fractures may be at high risk for treatment failure in an external orthosis. CASE DESCRIPTION We report on a case of an oblique axis fracture that failed treatment with external orthosis. Posterior instrumented fusion was employed successfully using a C1-C3 and C4 poly axial screw rod construct. Frameless stereotaxy and a biomodel were useful surgical adjuncts. Twelve month follow up revealed bony union in an asymptomatic patient. CONCLUSIONS Oblique fractures of the body of the axis can displace in a halo-thoracic orthosis. Serial radiological review is required to detect displacement prior to fracture union. Oblique fractures of the body of the axis can be managed surgically with preservation of atlanto-occipital motion, resulting in satisfactory clinical and radiological outcomes.
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Affiliation(s)
- Tony Goldschlager
- Department of Neurosurgery, The Alfred Hospital, Victoria 3181, Australia.
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Shaw MN, Morel EP, Utter PA, Gussous YM, Ginoux L, Berglund LJ, Gay RE, Krauss WE. Transverse connectors providing increased stability to the cervical spine rod-screw construct: an in vitro human cadaveric study. J Neurosurg Spine 2011; 14:719-25. [DOI: 10.3171/2011.1.spine10411] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Object
The object of this study was to determine if the addition of transverse connectors (TCs) to a rod-screw construct leads to increased stabilization of the cervical spine.
Methods
Eleven human cadaveric cervical spines (C2–T1) were used to examine the effect of adding connectors to a C3–7 rod-screw construct in 3 models of instability: 1) C3–6 wide laminectomy, 2) wide laminectomy and 50% foraminotomy at C4–5 and C5–6, and 3) wide laminectomy with full medial to lateral foraminotomy. Following each destabilization procedure, specimens were tested with no TC, 1 TC between the C-5 screws, and 2 TCs between the C-4 and C-6 screws. Testing of the connectors was conducted in random order. Specimens were subjected to ± 2 Nm of torque in flexion and extension, lateral bending, and axial rotation. Range of motion was determined for each experimental condition. Statistical comparisons were made between the destabilized and intact conditions, and between the addition of TCs and the absence of TCs.
Results
The progressive destabilization procedures significantly increased motion. The addition of TCs did not significantly change motion in flexion and extension. Lateral bending was significantly decreased with 2 connectors, but not with 1 connector. The greatest effect was on axial rotation. In general, 2 TCs were more restrictive than 1 TC, and decreased motion 10% more than fixation alone.
Conclusions
Regardless of the degree of cervical destabilization, 1 or 2 TCs decreased motion compared with rods and screws alone. Axial rotation was most affected. Transverse connectors effectively increase the rigidity of rod-screw constructs in the cervical spine. Severe cervical instability can be overcome with the use of 2 TCs, but in cases in which 2 cannot be used, 1 should be adequate and superior to none.
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Affiliation(s)
| | | | | | | | | | | | - Ralph E. Gay
- 1Biomechanics Laboratory, and
- 3Physical Medicine and Rehabilitation, Mayo Clinic, Rochester, Minnesota
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Lazaro BCR, Deniz FE, Brasiliense LBC, Reyes PM, Sawa AGU, Theodore N, Sonntag VKH, Crawford NR. Biomechanics of thoracic short versus long fixation after 3-column injury. J Neurosurg Spine 2011; 14:226-34. [DOI: 10.3171/2010.10.spine09785] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Object
Posterior screw-rod fixation for thoracic spine trauma usually involves fusion across long segments. Biomechanical data on screw-based short-segment fixation for thoracic fusion are lacking. The authors compared the effects of spanning short and long segments in the thoracic spine.
Methods
Seven human spine segments (5 segments from T-2 to T-8; 2 segments from T-3 to T-9) were prepared. Pure-moment loading of 6 Nm was applied to induce flexion, extension, lateral bending, and axial rotation while 3D motion was measured optoelectronically. Normal specimens were tested, and then a wedge fracture was created on the middle vertebra after cutting the posterior ligaments. Five conditions of instrumentation were tested, as follows: Step A, 4-level fixation plus cross-link; Step B, 2-level fixation; Step C, 2-level fixation plus cross-link; Step D, 2-level fixation plus screws at fracture site (index); and Step E, 2-level fixation plus index screws plus cross-link.
Results
Long-segment fixation restricted 2-level range of motion (ROM) during extension and lateral bending significantly better than the most rigid short-segment construct. Adding index screws in short-segment constructs significantly reduced ROM during flexion, lateral bending, and axial rotation (p < 0.03). A cross-link reduced axial rotation ROM (p = 0.001), not affecting other loading directions (p > 0.4).
Conclusions
Thoracic short-segment fixation provides significantly less stability than long-segment fixation for the injury studied. Adding a cross-link to short fixation improved stability only during axial rotation. Adding a screw at the fracture site improved short-segment stability by an average of 25%.
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Affiliation(s)
- Bruno C. R. Lazaro
- 1Division of Neurological Surgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona; and
| | - Fatih Ersay Deniz
- 2Faculty of Medicine, Department of Neurosurgery, Gaziosmanpasa University, Tokat, Turkey
| | - Leonardo B. C. Brasiliense
- 1Division of Neurological Surgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona; and
| | - Phillip M. Reyes
- 1Division of Neurological Surgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona; and
| | - Anna G. U. Sawa
- 1Division of Neurological Surgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona; and
| | - Nicholas Theodore
- 1Division of Neurological Surgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona; and
| | - Volker K. H. Sonntag
- 1Division of Neurological Surgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona; and
| | - Neil R. Crawford
- 1Division of Neurological Surgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona; and
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Zhao J, Zhang F, Chen X, Yao Y. Posterior interbody fusion using a diagonal cage with unilateral transpedicular screw fixation for lumbar stenosis. J Clin Neurosci 2011; 18:324-8. [PMID: 21237659 DOI: 10.1016/j.jocn.2010.06.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2010] [Revised: 06/11/2010] [Accepted: 06/15/2010] [Indexed: 01/04/2023]
Abstract
Few reports have described the combined use of unilateral pedicle screw fixation and interbody fusion for lumbar stenosis. We retrospectively reviewed 79 patients with lumbar stenosis. The rationale and effectiveness of unilateral pedicle screw fixation were studied from biomechanical and clinical perspectives, aiming to reduce stiffness of the implant. All patients were operated with posterior interbody fusion using a diagonal cage in combination with unilateral transpedicular screw fixation and had reached the 3-year follow-up interval after operation. The mean operating time was 115 minutes (range=95-150 min) and the mean estimated blood loss was 150 mL (range=100-200 mL). The mean duration of hospital stay was 10 days (range=7-15 days). Clinical outcomes were assessed prior to surgery and reassessed at intervals using Denis' pain and work scales. Fusion status was determined from X-rays and CT scans. At the final follow-up, the clinical results were satisfactory and patients showed significantly improved scores (p<0.01) either on the pain or the work scale. Successful fusion was achieved in all patients. There were no new postoperative radiculopathies, or instances of malpositioned or fractured hardware. Posterior interbody fusion using a diagonal cage with unilateral transpedicular fixation is an effective treatment for decompressive surgery for lumbar stenosis.
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Affiliation(s)
- Jian Zhao
- Spinal Center, Affiliated Hospital of Nantong University, 20 Xisi Road, Nantong 226001, Jiangsu, China.
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Bishop FS, Samuelson MM, Finn MA, Bachus KN, Brodke DS, Schmidt MH. The biomechanical contribution of varying posterior constructs following anterior thoracolumbar corpectomy and reconstruction. J Neurosurg Spine 2010; 13:234-9. [PMID: 20672960 DOI: 10.3171/2010.3.spine09267] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECT Thoracolumbar corpectomy is a procedure commonly required for the treatment of various pathologies involving the vertebral body. Although the biomechanical stability of anterior reconstruction with plating has been studied, the biomechanical contribution of posterior instrumentation to anterior constructs remains unknown. The purpose of this study was to evaluate biomechanical stability after anterior thoracolumbar corpectomy and reconstruction with varying posterior constructs by measuring bending stiffness for the axes of flexion/extension, lateral bending, and axial rotation. METHODS Seven fresh human cadaveric thoracolumbar spine specimens were tested intact and after L-1 corpectomy and strut grafting with 4 different fixation techniques: anterior plating with bilateral, ipsilateral, contralateral, or no posterior pedicle screw fixation. Bending stiffness was measured under pure moments of +/- 5 Nm in flexion/extension, lateral bending, and axial rotation, while maintaining an axial preload of 100 N with a follower load. Results for each configuration were normalized to the intact condition and were compared using ANOVA. RESULTS Spinal constructs with anterior-posterior spinal reconstruction and bilateral posterior pedicle screws were significantly stiffer in flexion/extension than intact spines or spines with anterior plating alone. Anterior plating without pedicle screw fixation was no different from the intact spine in flexion/extension and lateral bending. All constructs had reduced stiffness in axial rotation compared with intact spines. CONCLUSIONS The addition of bilateral posterior instrumentation provided significantly greater stability at the thoracolumbar junction after total corpectomy than anterior plating and should be considered in cases in which anterior column reconstruction alone may be insufficient. In cases precluding bilateral posterior fixation, unilateral posterior instrumentation may provide some additional stability.
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Affiliation(s)
- Frank S Bishop
- Department of Neurosurgery, University of Utah, Salt Lake City, Utah, USA
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Biomechanical comparisons of different posterior instrumentation constructs after two-level ALIF: A finite element study. Med Eng Phys 2010; 32:203-11. [DOI: 10.1016/j.medengphy.2009.12.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2009] [Revised: 12/08/2009] [Accepted: 12/13/2009] [Indexed: 11/18/2022]
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Biomechanical evaluation of short-segment posterior instrumentation with and without crosslinks in a human cadaveric unstable thoracolumbar burst fracture model. Spine (Phila Pa 1976) 2010; 35:278-85. [PMID: 20075769 DOI: 10.1097/brs.0b013e3181bda4e6] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN This study evaluates the biomechanical characteristics of spinal instrumentation constructs in a human unstable thoracolumbar burst fracture model simulated by corpectomy. OBJECTIVE To compare the biomechanical characteristics of short-segment posterior instrumentation, with and without crosslinks, in a human unstable burst fracture model simulated by corpectomy. SUMMARY OF BACKGROUND DATA Unstable thoracolumbar burst fractures are serious injuries, and their management remains controversial. Some authors advocate the use of short-segment posterior instrumentation for certain burst fractures. Whether crosslinks contribute additional stability has not been determined. METHODS Six fresh frozen human spines (T10-L2) were potted to isolate the T11-L1 segments, and biomechanically tested in axial rotation, lateral bending, flexion, and extension. A custom spine testing system was used that allows motion with 6 degrees of freedom. After testing was completed on intact specimens, a corpectomy was performed at T12 to simulate an unstable burst fracture with loss of anterior and middle column support. Short-segment transpedicular instrumentation was then performed from T11 to L1. Each specimen was retested with 1, 2, or no crosslinks. Construct stiffness and motion data were analyzed with each intact specimen serving as its own internal control. RESULTS Torsional stiffness in axial rotation was significantly increased (P < 0.05) in short-segment fixation constructs with 1 and 2 crosslinks, but none was restored to the preinjury baseline level. Significant reductions in standardized motion were also achieved with 1 and 2 crosslinks compared to no crosslinks (P < 0.05), but they remained greater than baseline. Crosslinks significantly increased stiffness and decreased motion in lateral bending, beyond the baseline level (P < 0.05). In flexion, all constructs had significantly decreased stiffness and increased motion compared to the intact specimen (P < 0.05), with crosslinks providing no additional benefit. Conversely, none of the constructs demonstrated a significant change in extension compared to baseline (P > 0.05). When attempting to load the constructs to failure, screw pullout was seen in all specimens. CONCLUSION Crosslinks, when added to short-segment posterior fixation, improve stiffness and decrease motion in axial rotation, but do not restore baseline stability in this corpectomy model. Short-segment posterior fixation is also inadequate in restoring stability in flexion with injuries of this severity. Short-segment posterior instrumentation alone can achieve baseline stability in lateral bending, and crosslinks provide even greater stiffness.
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Wu JC, Huang WC, Chen YC, Shih YH, Cheng H. Stabilization of subaxial cervical spines by lateral mass screw fixation with modified Magerl's technique. ACTA ACUST UNITED AC 2009; 70 Suppl 1:S1:25-33; discussion S1:33. [PMID: 19061767 DOI: 10.1016/j.surneu.2008.02.036] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2007] [Accepted: 02/20/2008] [Indexed: 10/21/2022]
Abstract
BACKGROUND There are various techniques in lateral mass screw placement in the cervical spine currently available, including the Roy-Camille, Magerl, Anderson, and An techniques. Each has different entrance points and trajectories for screw insertion, and some even have different methods for different level of the subaxial cervical spine. The potential risk of vascular and neurologic injury varies with different techniques and different levels of the cervical spine. We proposed a modified technique with a universal method of screw placement suitable for stabilization of every level of the subaxial cervical spines, from C3 to C7. We have applied this modified technique on a large series of patients and obtained satisfactory results. METHODS A retrospective study was conducted of the charts, records, and clinical follow-up of 115 patients who received internal fixation with lateral mass screws and rods in the Department of Neurosurgery of Taipei Veterans General Hospital (Taipei, Taiwan) from 2004 to 2006. All patients received lateral mass screw placement in various levels of the subaxial cervical spines. The clinical and radiologic follow-up were carefully evaluated and analyzed. RESULTS All 115 patients with different pathological situations requiring stabilization received instrumentations with polyaxial screws and rod systems, in which 673 screws in total were used in various levels of the cervical spine between C3 and C7: 129 screws in C3, 115 in C4, 193 in C5, 101 in C6, and 135 in C7. The most often used screw length was 16 mm (385/673, 57%). Good bony fusion was observed in all patients except 1 (99.1%). The mean follow-up period was 14 months (4-35 months). No neurologic or vascular injury was noted clinically. Follow-up radiologic examinations found that the screw placements were well positioned. CONCLUSIONS Based on our experience, lateral mass fixation of subaxial cervical spines with our modified technique is safe and effective. This technique of lateral mass screw placement yielded good fusion rate with very few complications and can be considered as a good alternative compared to techniques previously reported by other authors. It can eliminate the need of different techniques for different level to be fixed. In the selected cases, skipped level fixation with this technique is also satisfactory.
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Affiliation(s)
- Jau-Ching Wu
- Department of Neurosurgery, Neurological Institute, Taipei Veterans General Hospital, School of Medicine, National Yang-Ming University, Taipei 11217, Taiwan, ROC.
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