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Kumar R, Kumar A, Kumari S, Kumar A. Biomechanical Analysis of Trapezoidal Thread Screw-Rod Fixation in Pedicle Section of Cervical Spine: A Finite-Element Analysis. Indian J Orthop 2024; 58:771-777. [PMID: 38812871 PMCID: PMC11130091 DOI: 10.1007/s43465-024-01170-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Accepted: 04/23/2024] [Indexed: 05/31/2024]
Abstract
Background Cervical pedicle screw-rod fixation presents a complex approach in spinal surgery, offering enhanced spine stabilization in variable conditions considering traumatic injuries, degenerative changes, as well as orthopaedic and oncological ailments. This technique employs small diameter screw implants strategically placed to bolster the mechanical integrity of the spine. Notably, it involves minimally invasive procedures, resulting in smaller incisions and reduced patient discomfort. This study aims to assess the effects of trapezoidal thread screws in pedicle sections of the cervical spine during flexion-extension loadings, focusing on factors such as range of motion (ROM), implant stress, and stress on adjacent bone. Methods Utilizing CT scan data, a finite element model of the cervical spine (C2-C7 vertebrae) was prepared. Trapezoidal thread screws were integrated into a single-level pedicle screw-rod fixation at the C5-C6 vertebrae. The C2 vertebra were given a compressive load of 50 N along with a moment of 1 Nm, resulting in the immobilization of the C7. Results and Discussion The results indicate a reduction in ROM at the C5-C6 level by 69% to 77% compared to the intact spine during flexion-extension loading, with a slight increase in ROM observed at adjacent cervical spine levels. Stress analysis revealed that the trapezoidal thread screws induced stresses ranging from 24 MPa to 29 MPa in PEEK trapezoidal screw-rod implants, which fall below the material's yield stress. Conclusions This suggests that the trapezoidal thread profile may be advantageous in minimizing stress concentration, attributed to its larger contact area with the vertebrae bone between the threads.
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Affiliation(s)
- Ram Kumar
- Department of Mechanical Engineering, National Institute of Technology, Patna, Bihar India
| | - Amit Kumar
- Department of Mechanical Engineering, National Institute of Technology, Patna, Bihar India
| | - Shabnam Kumari
- Department of Mathematics, Banaras Hindu University, Varanasi, India
| | - Alok Kumar
- Department of Mechanical Engineering, National Institute of Technology, Patna, Bihar India
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Pangnguriseng UA, Imade S, Furuya S, Nakazawa K, Shiraishi K, Sato M, Kawamura T, Uchio Y. Effect of bone density on the drill-hole diameter made by a cannulated drill bit in cancellous bone. J Orthop Sci 2024:S0949-2658(24)00058-7. [PMID: 38637192 DOI: 10.1016/j.jos.2024.04.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Revised: 03/05/2024] [Accepted: 04/06/2024] [Indexed: 04/20/2024]
Abstract
BACKGROUND When a pilot hole is made prior to a screw's insertion into bone, the same drill bit is used irrespective of the bone quality. However, osteoporotic bone is fragile and this may affect the hole diameter, which is of particular concern in cancellous bone. In this study, the relationship between bone density and drill-hole diameter was investigated assuming a pre-drilling process in screw-only osteosynthesis in the metaphysis and epiphysis. METHODS Two types of drill bit (triple-flute [T] and quadruple-flute [Q]) with different shapes and diameters were prepared: type T bits with 3.5 mm and 4.4 mm diameters, and type Q bits with 3.5 mm and 4.2 mm diameters. Drilling was performed manually in simulated bones with four densities: 5, 10, 15, and 20 pounds per cubic foot. We measured the hole diameters with a coordinate measuring machine and analyzed the relationship between the drill-hole diameters and the densities of the simulated bones. We then compared the screw pull-out strength between the two 3.5-diameter drill bits. RESULTS In all cases, the diameters of the drill holes were larger than those of the drill bits. The relationship between the drill-hole diameters and the bone densities was a negative linear correlation. Enlarging the hole diameter decreased the screw pull-out strength. CONCLUSIONS For cannulated drill bits of 3.5, 4.2 and 4.4 mm diameter, the diameter of the drill hole in cancellous bone obtained by the manual drilling technique tends to be larger in low-density (e.g., osteoporotic) compared to high-density (e.g., healthy) bone.
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Affiliation(s)
- Utomo Andi Pangnguriseng
- Department of Orthopaedic Surgery, Shimane University Faculty of Medicine, Shimane, Japan; Department of Orthopaedic, Faculty of Medicine, Universitas Muslim Indonesia, Sulawesi Selatan, Indonesia
| | - Shinji Imade
- Department of Orthopaedic Surgery, Shimane University Faculty of Medicine, Shimane, Japan.
| | - Satoshi Furuya
- Department of Manufacturing Technology, Shimane Institute for Industrial Technology, Shimane, Japan
| | - Koichiro Nakazawa
- Department of Manufacturing Technology, Shimane Institute for Industrial Technology, Shimane, Japan
| | - Kazuma Shiraishi
- Department of Manufacturing Technology, Shimane Institute for Industrial Technology, Shimane, Japan
| | - Masaya Sato
- Department of Orthopaedic Surgery, Shimane University Faculty of Medicine, Shimane, Japan
| | - Toshihiko Kawamura
- Division of Medical Informatics, Shimane University Faculty of Medicine, Shimane, Japan
| | - Yuji Uchio
- Department of Orthopaedic Surgery, Shimane University Faculty of Medicine, Shimane, Japan
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Long Z, Yu H, Yang H, Guo M, Meng L, Yuan H, Xiang L, Wang Q. Biomedical analysis of four fixation systems in treatment of type II traumatic spondylolisthesis of the axis: a finite element analysis. Med Biol Eng Comput 2024; 62:843-852. [PMID: 38052881 DOI: 10.1007/s11517-023-02981-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Accepted: 11/26/2023] [Indexed: 12/07/2023]
Abstract
This study aimed to compare the properties and safety of self-designed plates in type II traumatic spondylolisthesis of the axis with those of traditional devices via finite element (FE) analysis. We constructed a hangman's fracture FE model from the occipital bone (C0) level to the C3 level. Then, FE models were constructed for the following four fixation systems: an anterior cervical L-shaped plate with four vertebral screws (4-ACLP), or six screws (6-ACLP), an anterior cervical orion plate (ACOP), and a posterior fixation system. A preloaded compressive force of 50 N and a moment of 1.5 N·m were applied to each model under six working conditions. The mobility of the C2/3 segment decreased significantly in four fixation models. In the Mises stress cloud diagram, 4-ACLP showed a better stress distribution in both the bone graft and fixation system than 6-ACLP and ACOP. The resultant force of 4-ACLP was lower but higher than ACOP in axial force. Additionally, the cage in the 4-ACLP configuration experienced the highest stress in the six working conditions. Hence, this novel self-designed plate has the potential to mitigate the operational difficulties, provide sufficient stability, reduce the risk of plate or screw fractures, and improve bone fusion.
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Affiliation(s)
- Zuoyao Long
- General Hospital of Northern Theater Command, Shenyang, China
| | - Hailong Yu
- General Hospital of Northern Theater Command, Shenyang, China
| | - Huifeng Yang
- General Hospital of Northern Theater Command, Shenyang, China
| | - Mingming Guo
- General Hospital of Northern Theater Command, Shenyang, China
| | - Lingzhi Meng
- General Hospital of Northern Theater Command, Shenyang, China
| | - Hong Yuan
- General Hospital of Northern Theater Command, Shenyang, China
| | - Liangbi Xiang
- General Hospital of Northern Theater Command, Shenyang, China.
| | - Qi Wang
- General Hospital of Northern Theater Command, Shenyang, China.
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Hu Z, Ren W, Peng J, Gu Z, Wu C, Wu W, Zhang W, Xu W, Li L. Biomechanics and finite element analysis comparing posterior T-plates with LCP for fixation of posterolateral tibial plate fractures. Front Bioeng Biotechnol 2023; 11:1286993. [PMID: 38130819 PMCID: PMC10733506 DOI: 10.3389/fbioe.2023.1286993] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Accepted: 11/27/2023] [Indexed: 12/23/2023] Open
Abstract
Objective: The treatment for posterolateral tibial plateau fractures (PTPF) have been subjects of controversy. We conducted a study to improve the fixation of PTPF through a lateral approach. Methods: We utilized 40 synthetic tibias and categorized the fracture models into five groups based on the locking compression plate (LCP) and T-distal radius plate (TPP) via various forms of fixation with screws through the posterolateral (PL) fracture fragments. I: Two-screw fixation using two locking screws (LPTL). Ⅱ: Two-screw fixation with both variable angle locking screws (LPTV). Ⅲ: One-screw fixation with one locking screw (LPOL). Ⅳ: One-screw fixation with one locking screw and two anteroposterior lag screws (LPOLTL). Ⅴ: a distal radius plate with three locking screws (TPP). Biomechanical tests were conducted to observe the axial compression displacement of the PL fracture fragments at force levels of 250 N, 500 N, and 750 N, as well as to determine the failure load and the axial stiffness for each respective group. Results: Under a 750 N load condition, the displacements within the five experimental groups exhibited the following trend: Ⅴ < Ⅱ < Ⅰ< Ⅳ < Ⅲ. However, there were no significant differences between Group V and Group II, Group I and Group IV (p > 0.05), and only Group Ⅲ demonstrated a displacement exceeding 3 mm. The failure load and the axial stiffness exhibited the same trend. Conversely, statistical significance was identified among the remaining group compared with Group Ⅲ (p < 0.05). Regarding the finite element analysis, the maximum displacements for the five models under the load of 750 N exhibited the following trend: Ⅴ < Ⅱ < Ⅰ< Ⅳ < Ⅲ. The following trends were observed in maximum von Mises stresses for these models under the load of 750 N: Ⅴ < Ⅱ < Ⅳ< Ⅰ < Ⅲ. Conclusion: It is crucial to address the inadequate mechanical strength associated with single screw fixation of LCP for fixing PL fractures in a clinical setting. The biomechanical strength of two-screw fixation surpasses that of single-screw fixation. Introducing variable-angle screws can further enhance the fixation range. Furthermore, the addition of two lag screws threaded from anterior to posterior can compensate the mechanical stability, when PL fracture is fixed with single screw in clinic.
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Affiliation(s)
- Zhenghui Hu
- Department of Orthopedics, The Second Affiliated Hospital of Soochow University, Suzhou, China
| | - Weizhi Ren
- Department of Orthopedics, The Second Affiliated Hospital of Soochow University, Suzhou, China
| | - Jian Peng
- Department of Orthopedics, The Second Affiliated Hospital of Soochow University, Suzhou, China
| | - Zenghui Gu
- Department of Orthopedics, The Second Affiliated Hospital of Soochow University, Suzhou, China
| | - Chenying Wu
- Department of Orthopedics, The Second Affiliated Hospital of Soochow University, Suzhou, China
| | - Weicheng Wu
- Department of Orthopedics, The Second Affiliated Hospital of Soochow University, Suzhou, China
| | - Wen Zhang
- Orthopedic Institute of Soochow University, Suzhou, China
| | - Wei Xu
- Department of Orthopedics, The Second Affiliated Hospital of Soochow University, Suzhou, China
| | - Liubing Li
- Department of Orthopedics, The Second Affiliated Hospital of Soochow University, Suzhou, China
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Betts JL, Brinkley FM, Priddy LB, Priddy MW. Low-speed instrumented drill press for bone screw insertion. HARDWAREX 2023; 16:e00474. [PMID: 37771322 PMCID: PMC10522896 DOI: 10.1016/j.ohx.2023.e00474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Revised: 05/24/2023] [Accepted: 09/07/2023] [Indexed: 09/30/2023]
Abstract
Screw insertion torque is a widely used/effective method for quantifying fixation strength in orthopedic implant research for different screw geometries, implantation sites, and loads. This work reports the construction of an open-source instrumented benchtop screw insertion device for a total cost of $7545 ($492 + $7053 for equipped sensors), as well as validation of the device and an example use-application. The insertion device is capable of recording the axial load, rotational speed, and applied torque throughout the screw insertion process at 10 samples per second, as demonstrated in the validation test. For this combination of bone analog (20 PCF Sawbones©), screw, and loading, the resolution of the torque sensor was 25% of the maximum measured torque; a different model torque sensor would be required to meet ASTM F543-17, which specifies a resolution of 10% of the maximum torque. This system is optimized for fastener insertion at speeds of 120 rpm or less and axial loading up to 50 N.
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Affiliation(s)
- J. Logan Betts
- Department of Mechanical Engineering, Mississippi State University, Mississippi State, MS 39762, United States of America
- Center for Advanced Vehicular Systems, Mississippi State University, Starkville, MS 39759, United States of America
| | - Frank M. Brinkley
- Department of Mechanical Engineering, Mississippi State University, Mississippi State, MS 39762, United States of America
- Center for Advanced Vehicular Systems, Mississippi State University, Starkville, MS 39759, United States of America
| | - Lauren B. Priddy
- Department of Agricultural and Biological Engineering, Mississippi State University, Mississippi State, MS 39762, United States of America
| | - Matthew W. Priddy
- Department of Mechanical Engineering, Mississippi State University, Mississippi State, MS 39762, United States of America
- Center for Advanced Vehicular Systems, Mississippi State University, Starkville, MS 39759, United States of America
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Zhao G, He S, Chen E, Ma T, Wu K, Wu J, Li W, Song C. Biomechanical effects of osteoporosis severity on the occurrence of proximal junctional kyphosis following long-segment posterior thoracolumbar fusion. Clin Biomech (Bristol, Avon) 2023; 110:106132. [PMID: 37924756 DOI: 10.1016/j.clinbiomech.2023.106132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Revised: 10/17/2023] [Accepted: 10/23/2023] [Indexed: 11/06/2023]
Abstract
BACKGROUND Proximal junctional kyphosis is a common long-term complication in adult spinal deformity surgery that involves long-segment posterior spinal fusion. However, the underlying biomechanical mechanisms of the impact of osteoporosis on proximal junctional kyphosis remain unclear. The present study was to evaluate adjacent segment degeneration and spine mechanical instability in osteoporotic patients who underwent long-segment posterior thoracolumbar fusion. METHODS Finite element models of the thoracolumbar spine T1-L5 with posterior long-segment T8-L5 fusion under different degrees of osteoporosis were constructed to analyze intervertebral disc stress characterization, vertebrae mechanical transfer, and pedicle screw system loads during various motions. FINDINGS Compared with normal bone mass, the maximum von Mises stresses of T7 and T8 were increased by 20.32%, 22.38%, 44.69%, 4.49% and 29.48%, 17.84%, 40.95%, 3.20% during flexion, extension, lateral bending, and axial rotation in the mild osteoporosis model, and by 21.21%, 18.32%, 88.28%, 2.94% and 37.76%, 15.09%, 61.47%, -0.04% in severe osteoporosis model. The peak stresses among T6/T7, T7/T8, and T8/T9 discs were 14.77 MPa, 11.55 MPa, and 2.39 MPa under lateral bending conditions for the severe osteoporosis model, respectively. As the severity of osteoporosis increased, stress levels on SCR8 and SCR9 intensified during various movements. INTERPRETATION Osteoporosis had an adverse effect on proximal junctional kyphosis. The stress levels in cortical bone, intervertebral discs and screws were increased with bone mass loss, which can easily lead to intervertebral disc degeneration, bone destruction as well as screw pullout. These factors have significantly affected or accelerated the occurrence of proximal junctional kyphosis.
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Affiliation(s)
- Gaiping Zhao
- School of Health Science and Engineering, University of Shanghai for Science and Technology, Shanghai 200093, PR China.
| | - Shenglan He
- School of Health Science and Engineering, University of Shanghai for Science and Technology, Shanghai 200093, PR China
| | - Eryun Chen
- School of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai 200093, PR China
| | - Tong Ma
- Department of Bone and Joint Surgery, Yangpu Hospital, School of Medicine, Tongji University, Shanghai 200090, China
| | - Kunneng Wu
- Shanghai Institute of Medical Device Testing, Shanghai 201318, China
| | - Jie Wu
- Key Laboratory of Hydrodynamics, School of Naval Architecture, Ocean and Civil Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Weiqi Li
- School of Health Science and Engineering, University of Shanghai for Science and Technology, Shanghai 200093, PR China
| | - Chengli Song
- School of Health Science and Engineering, University of Shanghai for Science and Technology, Shanghai 200093, PR China
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Yun C, Qian W, Zhang J, Zhang W, Lv J. Biomechanics of PHILOS plates in Vancouver B1 periprosthetic femoral fracture. Front Bioeng Biotechnol 2023; 11:1282128. [PMID: 38047287 PMCID: PMC10690819 DOI: 10.3389/fbioe.2023.1282128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Accepted: 11/08/2023] [Indexed: 12/05/2023] Open
Abstract
Objective: To investigate the clinical efficacy of PHILOS plates in the treatment of Vancouver B1 periprosthetic femoral fracture (PFF) and to validate its biomechanical reliability via finite element analysis and mechanical testing on the Synbone femoral models. Methods: Ten males and eight females with Vancouver B1 PFF who underwent PHILOS plate fixation between September 2017 and January 2022 were selected. The average age was 72.61 ± 8.19 years, with a range of 57-86 years old. X-ray films were taken to assess the fracture healing situation around the femoral prosthesis as well as the position of the PHILOS plates and femoral prosthesis. Two different plates (the PHILOS plate and the Cable GTR plate) were used for fixation, and the differences in biomechanical stability of the two fixation methods were compared using finite element analysis and mechanical testing on the Synbone femoral models to validate the biomechanical dependability of the PHILOS plate. Results: All 18 cases were followed for at least 1 year, as a result. The average period of follow-up was 17 months, ranging from 12 to 36 months. At the most recent follow-up, Harris scores for the hip joints of patients ranged from 82 to 89, with an average score of 86. The X-rays revealed that all fractures surrounding the femoral prosthesis had healed and that there was no looseness in the femoral prosthesis. None of the PHILOS license plates had expired. All patients were able to perform full-load walking, and pain and claudication in affected limbs were significantly reduced. Finite element analysis and mechanical testing of the Synbone femoral model revealed that the fixation effect of the PHILOS group was superior to that of the Cable group; consequently, PHILOS plates can be used to effectively fix fractures around the proximal femoral prosthesis. Conclusion: PHILOS plates are initially used in the treatment of Vancouver B1 PFF, which may be a good choice due to their simpler operation, lower medical costs, and satisfactory clinical efficacy.
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Affiliation(s)
- Changjun Yun
- Departmeut of Orthopaedics, The Affiliated Wujin Hospital of Jiangsu University, Changzhou, China
- The Wujin Clinical College of Xuzhou Medical University, Changzhou, China
| | - Wenjie Qian
- Departmeut of Orthopaedics, The Affiliated Wujin Hospital of Jiangsu University, Changzhou, China
- The Wujin Clinical College of Xuzhou Medical University, Changzhou, China
| | - Jie Zhang
- Departmeut of Orthopaedics, The Affiliated Wujin Hospital of Jiangsu University, Changzhou, China
- The Wujin Clinical College of Xuzhou Medical University, Changzhou, China
| | - Wen Zhang
- Orthopedic Institute, Soochow University, Suzhou, China
| | - Jinpeng Lv
- School of Pharmacy, Changzhou University, Changzhou, China
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Pye JL, Garcia TC, Kapatkin AS, Samol MA, Stover S. Biomechanical comparison of compact versus standard flute drill bits, and interlocking versus buttress thread self-tapping cortical bone screws in cadaveric equine third metacarpal condyle. Vet Surg 2023; 52:1128-1139. [PMID: 37302003 DOI: 10.1111/vsu.13965] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 03/17/2023] [Accepted: 04/16/2023] [Indexed: 06/12/2023]
Abstract
OBJECTIVES To compare (1) performance of compact versus standard flute drill bits, (2) screw insertion properties and (3) pullout variables between interlocking thread (ITS) and buttress thread (BTS) self-tapping screws in third metacarpi. STUDY DESIGN In vitro experimental study. SAMPLE POPULATION Paired third metacarpi from 11 Thoroughbreds aged 2-4 years. METHODS Screws were inserted into the lateral condylar fossae following bone preparation using the respective drill bit for each screw type. Screw pullout was achieved using a mechanical testing system. Density and porosity of bone surrounding screw holes was measured with microcomputed tomography following each pullout test. Drilling, screw insertion and pullout variables were compared between drill bit and screw types using repeated measures ANOVA. Linear regression analyses were used to characterize relationships between bone tissue properties and drill bit and screw outcomes. RESULTS Maximum torque power spectral density (PSD) was lower for compact flute drill bits. Insertion torque was 50% higher for ITS. BTS had 33% greater preyield stiffness and 7% greater mean yield force. Bone tissue properties affected measured variables similarly for both screw and drill bit types. CONCLUSIONS Lower torque PSD may increase durability of the compact flute drill bit. ITS had greater insertional torque, which may reflect greater bone engagement. BTS had greater resistance to axial pullout forces. CLINICAL SIGNIFICANCE Metacarpal bone provides a simple model for comparison of drill bit and screw designs. Use of ITS to repair equine fractures subject to predominantly tensile forces is not justified based on the results of this study.
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Affiliation(s)
- Jannah L Pye
- William R. Pritchard Veterinary Medical Teaching Hospital, School of Veterinary Medicine, University of California-Davis, Davis, California, USA
| | - Tanya C Garcia
- JD Wheat Veterinary Orthopedic Research Laboratory, School of Veterinary Medicine, University of California-Davis, Davis, California, USA
| | - Amy S Kapatkin
- JD Wheat Veterinary Orthopedic Research Laboratory, School of Veterinary Medicine, University of California-Davis, Davis, California, USA
- Department of Surgical & Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, California, USA
| | - Monika A Samol
- California Animal Health and Food Safety System, San Bernadino Branch, School of Veterinary Medicine, University of California-Davis, Davis, California, USA
| | - Susan Stover
- JD Wheat Veterinary Orthopedic Research Laboratory, School of Veterinary Medicine, University of California-Davis, Davis, California, USA
- Department of Surgical & Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, California, USA
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Yu A, Imade S, Furuya S, Nakazawa K, Shiraishi K, Kawamura T, Uchio Y. Relationship between thread depth and fixation strength in cancellous bone screw. J Orthop Sci 2023; 28:1143-1148. [PMID: 35953407 DOI: 10.1016/j.jos.2022.07.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 06/11/2022] [Accepted: 07/06/2022] [Indexed: 11/22/2022]
Abstract
BACKGROUND Clarifying the effect of each parameter of screw design on its fixation strength is critical in the development of any type of screw. The purpose of this study was to clarify the relationship between the thread depth and fixation strength of metal screws for cancellous bone. METHODS Nine types of custom-made screws with the only changed variable being the thread depth were manufactured. Other elements were fixed at a major diameter of 4.5 mm, a thread region length of 15 mm, a pitch of 1.6 mm, and a thread width of 0.20 mm. The pull-out strength and insertion torque of each screw were measured for each of two foam-block densities (10 or 20 pcf). The correlation between the thread depth of the screw and the mechanical findings were investigated with single regression analysis. RESULTS Regardless of the foam-block density, the pull-out strength significantly increased as the thread depth increased from 0.1 mm to 0.4 mm; after that, the increase was more gradual (p < 0.01, respectively). The relationship between the thread depth and insertion torque was similar. In addition, the insertion torque tended to be more strongly affected by screw depth than the pull-out strength (2.6 times at 20 pcf and 1.4 times at 10 pcf). CONCLUSIONS The pull-out strength of 4.5-mm-diameter metal screws in a cancellous bone model was found to be biphasic, although linearly correlated with the change in screw depth in both phases. The boundary of the correlation was 0.4 mm regardless of the density of the bone model, with the effect of screw depth on pull-out strength beyond that being small in comparison.
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Affiliation(s)
- Aorigele Yu
- Department of Orthopaedic Surgery, Shimane University Faculty of Medicine, Shimane, Japan
| | - Shinji Imade
- Department of Orthopaedic Surgery, Shimane University Faculty of Medicine, Shimane, Japan.
| | - Satoshi Furuya
- Department of Mechanical Technology, Shimane Institute for Industrial Technology, Shimane, Japan
| | - Koichiro Nakazawa
- Department of Mechanical Technology, Shimane Institute for Industrial Technology, Shimane, Japan
| | - Kazuma Shiraishi
- Department of Mechanical Technology, Shimane Institute for Industrial Technology, Shimane, Japan
| | - Toshihiko Kawamura
- Division of Medical Informatics, Shimane University Faculty of Medicine, Shimane, Japan
| | - Yuji Uchio
- Department of Orthopaedic Surgery, Shimane University Faculty of Medicine, Shimane, Japan
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Bregoli C, Stacchiotti F, Fiocchi J, Ferrari R, Biffi CA, Morellato K, Gruppioni E, Tuissi A. A biomechanical study of osseointegrated patient-matched additively manufactured implant for treatment of thumb amputees. Med Eng Phys 2023; 118:104019. [PMID: 37536840 DOI: 10.1016/j.medengphy.2023.104019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Accepted: 07/01/2023] [Indexed: 08/05/2023]
Abstract
Thumb amputations leads to 50 % loss in hand functionality. To date, silicone vacuum prosthesis and autologous transplantation are the most adopted treatment solutions: nevertheless, vacuum prostheses lack in stability and cause skin issue and surgical treatment is not always accepted by patients. Osseointegrated implants were demonstrated to enhance stability, restore osseoperception and increase the time of prosthesis use. Thumb amputations present varying stump sizes: a standard size implant cannot address specificity of each patient, while a patient matched solution can meet surgeon requirements, by geometrical features of implant. The fixture presented in the current paper is the first additively manufactured patient matched osseointegrated implant for the treatment of thumb amputees. The current work aims to verify and validate a predictive finite element model (FEM) for mechanical strength of the presented fixture. FEM was demonstrated to correctly evaluate the mechanical strength of patient matched device. Minimum strength requirements were calculated in different core diameters: FEM were experimentally validated. Safety factor of 1.5 was guaranteed. Finally, considerations on performance of the prototype were carried out by means of insertion tests in Sawbones and axial pull-out force assessment. Cadaver tests to evaluate the entire procedure and production process are ongoing.
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Affiliation(s)
- Chiara Bregoli
- CNR ICMATE, National Research Council, Unit of Lecco, Via Previati 1/e, 23900, Lecco, Italy.
| | - Federico Stacchiotti
- Istituto di BioRobotica, Scuola Superiore Sant'Anna, Viale Rinaldo Piaggio 34, 56025, Pontedera, Pisa, italy
| | - Jacopo Fiocchi
- CNR ICMATE, National Research Council, Unit of Lecco, Via Previati 1/e, 23900, Lecco, Italy
| | - Rubens Ferrari
- Istituto di BioRobotica, Scuola Superiore Sant'Anna, Viale Rinaldo Piaggio 34, 56025, Pontedera, Pisa, italy
| | - Carlo Alberto Biffi
- CNR ICMATE, National Research Council, Unit of Lecco, Via Previati 1/e, 23900, Lecco, Italy
| | - Kavin Morellato
- INAIL Centro Protesi, via Rabuina 14, Vigorso di Budrio, 40054, Bologna, Italy
| | - Emanuele Gruppioni
- INAIL Centro Protesi, via Rabuina 14, Vigorso di Budrio, 40054, Bologna, Italy
| | - Ausonio Tuissi
- CNR ICMATE, National Research Council, Unit of Lecco, Via Previati 1/e, 23900, Lecco, Italy
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Tang W, Jian Q, Dong C, Chen T, Liu B. Development and validation of a specialized system for self-tapping medical bone screw testing. Med Eng Phys 2023; 118:104005. [PMID: 37331898 DOI: 10.1016/j.medengphy.2023.104005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Revised: 05/04/2023] [Accepted: 06/07/2023] [Indexed: 06/20/2023]
Abstract
A specialized system for accurate self-tapping medical bone screw testing is developed, fully meeting the requirements of ASTM F543-A4 (YY/T 1505-2016). The onset of self-tap is identified automatically according to a change in the slope of the torque curve. Precise load control is applied to determine the self-tapping force accurately. A simple mechanical platform is embedded to ensure the automatic axial alignment of a tested screw with the pilot hole in a test block. In addition, comparative experiments are conducted on different self-tapping screws to verify the system's effectiveness. By the automatic identification and alignment method, both torque curves and axial force curves for each screw exhibit significant consistency. The self-tapping time point derived from the torque curve agrees well with the turning point of the axial displacement curve. The determined self-tapping forces' mean values and standard deviations are both small, which are proved to be effective and accurate in the insertion tests. This work contributes to improving the standard test method for accurate determination of the self-tapping performance of medical bone screws.
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Affiliation(s)
- Wenlong Tang
- School of Mechanical and Automotive Engineering, Shanghai University of Engineering Science, Shanghai 201620, China
| | - Qiwei Jian
- School of Mechanical and Automotive Engineering, Shanghai University of Engineering Science, Shanghai 201620, China.
| | - Chengzhi Dong
- Shanghai Duratt Instrument Co., Ltd., Shanghai 201613, China
| | - Tianqi Chen
- Shanghai Duratt Instrument Co., Ltd., Shanghai 201613, China
| | - Bin Liu
- School of Mechanical and Automotive Engineering, Shanghai University of Engineering Science, Shanghai 201620, China.
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12
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Huang P, Chen J, Su Y, Luo H, Lee PC, Lan X, Wang L, Shen B, Zhao Y, Wu F, Zheng W. Transforming Waste Polystyrene into High-Performance Porous Frames with Tunable Cellular Structures via Supercritical Nitrogen Foaming. Ind Eng Chem Res 2022. [DOI: 10.1021/acs.iecr.2c01709] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Pengke Huang
- Ningbo Key Lab of Polymer Materials, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang Province 315201, China
| | - Jiayun Chen
- College of General Aviation and Flight, Nanjing University of Aeronautics & Astronautics, Changzhou, Jiangsu Province 213001, China
| | - Yaozhuo Su
- Ningbo Key Lab of Polymer Materials, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang Province 315201, China
| | - Haibin Luo
- Ningbo Key Lab of Polymer Materials, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang Province 315201, China
| | - Patrick C. Lee
- Multifunctional Composites Manufacturing Laboratory, Department of Mechanical and Industrial Engineering, University of Toronto, 5 King’s College Road, Toronto M5G3G8, Ontario, Canada
| | - Xiaoqin Lan
- Ningbo Key Lab of Polymer Materials, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang Province 315201, China
| | - Long Wang
- Ningbo Key Lab of Polymer Materials, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang Province 315201, China
| | - Bin Shen
- Ningbo Key Lab of Polymer Materials, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang Province 315201, China
| | - Yongqing Zhao
- Ningbo Key Lab of Polymer Materials, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang Province 315201, China
| | - Fei Wu
- Ningbo Key Lab of Polymer Materials, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang Province 315201, China
| | - Wenge Zheng
- Ningbo Key Lab of Polymer Materials, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang Province 315201, China
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13
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Novel Dual-Threaded Pedicle Screws Provide Fixation Stability That Is Comparable to That of Traditional Screws with Relative Bone Preservation: An In Vitro Biomechanical Study. APPLIED SCIENCES-BASEL 2022. [DOI: 10.3390/app12126172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Replacement with larger diameter screws is always used in pedicle screw loosening but carries a risk of pedicle wall violation. A pedicle screw with more preserved bone stock is the preferred primary fixation choice. The purpose of this study was to evaluate whether a newly designed proximal-conical dual-thread screw with less bone occupancy provides fixation strength comparable to that of a traditional screw. Six types of pedicle screws based on three different shapes (cylindrical, conical, and proximal-conical) and two thread profiles (single-thread and dual-thread) were grouped. Conical and proximal-conical screws differed mainly in the slope of the outer diameter from the hub to the tip. Conical screws had an outer diameter (6.5 mm) that differed from the hub and tapered by 30% to an outer diameter (4.5 mm) at the tip and proximal-conical screws had the same outer diameter from the hub and tapered by 30% (4.5 mm) at 20 mm from the hub and then maintained the outer diameter (45 mm) to the tip. A total of 36 L4 Sawbones® vertebrae were used in the study and six trials for each screw group. The results of the imaging, screw volume in bone, insertion torque, and pullout force were analyzed. For screws with the same shape, insertion torque and pullout force were significantly higher for those in the dual-thread groups than for those in the single-thread groups (p < 0.05). For screws with the same thread profile, there was no significant difference in either biomechanical test between the different screw shapes (p > 0.05). Our results demonstrated that these proximal-conical dual-thread screws, with the property of relative bone stock preservation, display a comparable biomechanical performance to traditional dual-thread screws and a better performance than single-thread screws. This screw design could serve as the primary pedicle screw choice to reduce revision difficulty.
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14
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Qiu L, Niu F, Wu Z, Zhang W, Chen F, Tan J, Yan J, Xia P. Comparative outcomes of cortical bone trajectory screw fixation and traditional pedicle screws in lumbar fusion: A meta-analysis. World Neurosurg 2022; 164:e436-e445. [PMID: 35533950 DOI: 10.1016/j.wneu.2022.04.129] [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: 03/09/2022] [Revised: 04/27/2022] [Accepted: 04/28/2022] [Indexed: 11/28/2022]
Abstract
BACKGROUND Pedicular screws (PS) is often used in lumbar fusion. Cortical bone trajectory (CBT) is a novel technology in lumbar fusion with less clinical outcomes evidence. So we conduct a meta-analysis to compare the efficacy and safety between cortical bone trajectory screw fixation and traditional pedicle screws in lumbar fusion surgery. METHODS Multiple databases were searched for the articles about comparison of cortical bone trajectory (CBT) and traditional pedicle screws (PS) in lumbar fusion surgeries. The Meta-analysis was conducted by Revman 5.3 software. The following indicators were abstracted: visual analog scale (VAS) scores for back and leg pain, Oswestry Disability Index (ODI), Japanese Orthopedic Association (JOA), surgical duration, complications, and blood loss. The quality of the articles was assessed by the Newcastle-Ottawa Scale or Cochrane Handbook. RESULTS 25 studies were included involving a total of 1735 patients. There is no difference in preoperative VAS scores, JOA, ODI, postoperative VAS scores and fusion rates. Besides, postoperative JOA(MD = 0.78, P = 0.02), ODI (MD = -2.09, P=0.03), surgical duration(MD = -26.90, P = 0.02), complications(MD = 0.70, P = 0.03), and blood loss(MD = -85.27, P=0.0009) showed greater improvement trends in CBT group than PS group with significant difference. CONCLUSION CBT reduced the rate of complications, surgical duration, blood loss, postoperative ODI and JOA scores. CBT technique with better postoperative outcomes achieved similar fusion rates compared with PS technique.
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Affiliation(s)
- Ling Qiu
- Xiaogan hosiptal of Chinese Medicine, 249 Huai-yin Road, Xiaogan 432100, P.R. China
| | - Fei Niu
- The Wuhan Hospital of Traditional Chinese And Western Medicine, 215 Zhong Shan Road, Wuhan 430022, P.R. China
| | - Zhedong Wu
- Hubei University of Chinese Medicine, 188 Tan Hua-lin Road, Wuhan 430065, P.R. China
| | - Wei Zhang
- The Wuhan Hospital of Traditional Chinese And Western Medicine, 215 Zhong Shan Road, Wuhan 430022, P.R. China
| | - Feifei Chen
- Xiaogan hosiptal of Chinese Medicine, 249 Huai-yin Road, Xiaogan 432100, P.R. China
| | - Jun Tan
- Xiaogan hosiptal of Chinese Medicine, 249 Huai-yin Road, Xiaogan 432100, P.R. China
| | - Jun Yan
- Xiaogan hosiptal of Chinese Medicine, 249 Huai-yin Road, Xiaogan 432100, P.R. China
| | - Ping Xia
- Hubei University of Chinese Medicine, 188 Tan Hua-lin Road, Wuhan 430065, P.R. China.
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15
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Cutting Flute and Thread Design on Self-Tapping Pedicle Screws Influence the Insertion Torque and Pullout Strength. APPLIED SCIENCES-BASEL 2022. [DOI: 10.3390/app12041956] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
Self-tapping screws are commonly used in trauma and maxillofacial surgery and are increasingly used for pedicle screw insertions. In order to evaluate how the quantity and length of cutting flutes on self-tapping pedicle screws affect the insertion torque and pullout strength, eight different self-tapping pedicle screw designs were evaluated. All screws had a threaded length of 35 mm and featured variations in the number of leads, as well as the length and quantity of cutting flutes. Five samples of each design were inserted into pre-drilled, untapped holes (ø2.7 mm, length 35 mm) in sawbone blocks of density 20 PCF. The insertion torque and pullout strength were measured according to ASTM F543. The results showed that screws with a longer cutting flute of 9.5 mm had a lower mean maximum insertion torque than screws with shorter 2.9 mm cutting flutes. Pedicle screws with a double-lead thread design had a greater insertion torque than their single-lead counterparts, and the use of three cutting flutes produced a lower torque than two cutting flutes. The results demonstrated a greater pullout strength in screws with a single-lead thread rather than a double-lead, three cutting flutes instead of two, and a longer length for the cutting flute. In conclusion, to provide immediate stability and reduce the surgical insertion time, a single-lead, self-tapping pedicle screw incorporating three long cutting flutes is recommended because of the significantly greater pullout strength. This design could also reduce the risk of implant loosening in comparison to double-lead, self-tapping pedicle screw designs.
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16
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Recommendations for standardised screw pull-out from polyurethane foam - The influence of density variations of the test foam and the insertion method. Med Eng Phys 2022; 100:103750. [DOI: 10.1016/j.medengphy.2022.103750] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2021] [Revised: 12/07/2021] [Accepted: 01/01/2022] [Indexed: 12/18/2022]
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17
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Samiezadeh A, McLachlin S, Ng M, Samiezadeh S, Larouche J, Whyne C. Modeling attachment and compressive loading of locking and non-locking plate fixation: a finite element investigation of a supracondylar femur fracture model. Comput Methods Biomech Biomed Engin 2022; 25:1629-1636. [PMID: 35098810 DOI: 10.1080/10255842.2022.2030730] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
This study developed a finite element (FE) model of simulated locking plate fixation to examine the strain response following supracondylar femoral plate attachment and under compressive loading. An implicit FE model of a synthetic femur with a distal fracture gap stabilized with a lateral plate was evaluated following attachment and 500 N loading, considering locking and non-locking proximal screws configurations. Screw pre-tension values of 60 N for both distal and proximal non-locking screws yielded good agreement with plate experimental strain data in attached (unloaded) and loaded conditions. The results highlight the importance of pre-tensioning in modeling plate attachment using non-locking screws.
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Affiliation(s)
- Amir Samiezadeh
- Orthopaedic Biomechanics Laboratory, Sunnybrook Research Institute, Toronto, ON, Canada.,Institute of Biomedical Engineering, University of Toronto, Toronto, ON, Canada
| | - Stewart McLachlin
- Mechanical & Mechatronics Engineering, University of Waterloo, Waterloo, ON, Canada
| | - Matthew Ng
- Orthopaedic Biomechanics Laboratory, Sunnybrook Research Institute, Toronto, ON, Canada
| | | | - Jeremie Larouche
- Orthopaedic Biomechanics Laboratory, Sunnybrook Research Institute, Toronto, ON, Canada.,Division of Orthopaedic Surgery, University of Toronto, Toronto, ON, Canada
| | - Cari Whyne
- Orthopaedic Biomechanics Laboratory, Sunnybrook Research Institute, Toronto, ON, Canada.,Institute of Biomedical Engineering, University of Toronto, Toronto, ON, Canada.,Department of Mathematics, Humber College, Toronto, ON, Canada
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Makaram H, Swaminathan R. Influence of bone quality and pedicle screw design on the fixation strength during Axial Pull-out test: A 2D Axisymmetric FE study. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2021; 2021:4924-4927. [PMID: 34892312 DOI: 10.1109/embc46164.2021.9629484] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Pedicle screw fixations are widely used to provide support and improve stability for the treatment of spinal pathologies. The effectiveness of treatment depends on the anchorage strength between the screw and bone. In this study, the influence of pedicle screw half-angle and bone quality on the displacement of fixation and stress transfer are analyzed using a 2D axisymmetric finite element model. The pedicle screw proximal half-angle is varied between 0° and 60° in steps of 10°, along with two different distal half-angles of 30° and 40°. Three bone models are considered for cancellous bone to simulate various degrees of bone quality, namely, poor, moderate and good. The mechanical properties of cortical bone are kept constant throughout the study. The material properties and boundary conditions are applied based on previous studies. Frictional contact is considered between the bone and screw. Results show that, the displacement of fixation is observed to be minimum at a proximal half angle of 0° and maximum at an angle of 60°, independent of bone quality. The highest implant displacement is observed in case of poor bone quality. All the bone model showed similar patterns of stress distribution, with high stress concentration around the first few threads. The highest peak von Mises stress is obtained at a proximal half-angle of 60°. Furthermore, the stress transfer increased with increase in proximal half-angle and bone quality, with maximum stress transfer at a proximal half-angle of 60°. It appears that, this study might aid to improve the design of pedicle screw for treatment of degenerative spinal diseases.Clinical Relevance- This study analyses the impact of bone quality on pedicle screw design.
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Biomechanical Comparison of Fixation Stability among Various Pedicle Screw Geometries: Effects of Screw Outer/Inner Projection Shape and Thread Profile. APPLIED SCIENCES-BASEL 2021. [DOI: 10.3390/app11219901] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The proper screw geometry and pilot-hole size remain controversial in current biomechanical studies. Variable results arise from differences in specimen anatomy and density, uncontrolled screw properties and mixed screw brands, in addition to the use of different tapping methods. The purpose of this study was to evaluate the effect of bone density and pilot-hole size on the biomechanical performance of various pedicle screw geometries. Six screw designs, involving three different outer/inner projections of screws (cylindrical/conical, conical/conical and cylindrical/cylindrical), together with two different thread profiles (square and V), were examined. The insertional torque and pullout strength of each screw were measured following insertion of the screw into test blocks, with densities of 20 and 30 pcf, predrilled with 2.7-mm/3.2-mm/3.7-mm pilot holes. The correlation between the bone volume embedded in the screw threads and the pullout strength was statistically analyzed. Our study demonstrates that V-shaped screw threads showed a higher pullout strength than S-shaped threads in materials of different densities and among different pilot-hole sizes. The configuration, consisting of an outer cylindrical shape, an inner conical shape and V-shaped screw threads, showed the highest insertional torque and pullout strength at a normal and higher-than-normal bone density. Even with increasing pilot-hole size, this configuration maintained superiority.
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20
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Addevico F, Solitro GF, Morandi MM. Salvaging Pull-Out Strength in a Previously Stripped Screw Site: A Comparison of Three Rescue Techniques. J Funct Morphol Kinesiol 2021; 6:jfmk6030071. [PMID: 34564190 PMCID: PMC8482251 DOI: 10.3390/jfmk6030071] [Citation(s) in RCA: 3] [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: 08/02/2021] [Revised: 08/21/2021] [Accepted: 08/24/2021] [Indexed: 11/16/2022] Open
Abstract
Screw stripping during bone fixation is a common occurrence during operations that results in decreased holding capacity and bone healing. We aimed to evaluate the rescue of the stripped screw site using screws of different dimensions. Five screw configurations were tested on cadaveric specimens for pull-out strength (POS). The configurations included a control screw tightened without stripping, a configuration voluntarily stripped and left in place, and three more configurations in which the stripped screws were replaced by a different screw with either increased overall length, diameter, or thread length. Each configuration was tested five times, with each screw tested once. The POS of the control screw, measured to be 153.6 ± 27 N, was higher than the POS measured after stripping and leaving the screw in place (57.1 ± 18 N, p = 0.001). The replacement of the stripped screw resulted in a POS of 158.4 ± 64 N for the screw of larger diameter, while the screws of the same diameter but increased length or those with extended thread length yielded POS values of 138.4 ± 42 and 185.7 ± 48 N, respectively. Screw stripping is a frequent intraoperative complication that, according to our findings, cannot be addressed by leaving the screw in place. The holding capacity of a stripped screw implanted in cancellous bone can successfully be restored with a different screw of either larger diameter, longer length, or extended thread length.
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Affiliation(s)
- Francesco Addevico
- Department of Orthopedic and Traumatology, Niguarda Hospital, 20162 Milano, Italy
- Correspondence:
| | - Giovanni F. Solitro
- Department of Orthopaedic Surgery, Louisiana State University Health-Shreveport, Shreveport, LA 71103, USA; (G.F.S.); (M.M.M.)
| | - Massimo Max Morandi
- Department of Orthopaedic Surgery, Louisiana State University Health-Shreveport, Shreveport, LA 71103, USA; (G.F.S.); (M.M.M.)
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