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Kerensky MJ, Paul A, Routkevitch D, Hersh AM, Kempski Leadingham KM, Davidar AD, Judy BF, Punnoose J, Williams A, Kumar A, Lehner K, Smith B, Son JK, Azadi JR, Shekhar H, Mercado-Shekhar KP, Thakor NV, Theodore N, Manbachi A. Tethered spinal cord tension assessed via ultrasound elastography in computational and intraoperative human studies. COMMUNICATIONS MEDICINE 2024; 4:4. [PMID: 38182729 PMCID: PMC10770351 DOI: 10.1038/s43856-023-00430-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Accepted: 12/19/2023] [Indexed: 01/07/2024] Open
Abstract
BACKGROUND Tension in the spinal cord is a trademark of tethered cord syndrome. Unfortunately, existing tests cannot quantify tension across the bulk of the cord, making the diagnostic evaluation of stretch ambiguous. A potential non-destructive metric for spinal cord tension is ultrasound-derived shear wave velocity (SWV). The velocity is sensitive to tissue elasticity and boundary conditions including strain. We use the term Ultrasound Tensography to describe the acoustic evaluation of tension with SWV. METHODS Our solution Tethered cord Assessment with Ultrasound Tensography (TAUT) was utilized in three sub-studies: finite element simulations, a cadaveric benchtop validation, and a neurosurgical case series. The simulation computed SWV for given tensile forces. The cadaveric model with induced tension validated the SWV-tension relationship. Lastly, SWV was measured intraoperatively in patients diagnosed with tethered cords who underwent treatment (spinal column shortening). The surgery alleviates tension by decreasing the vertebral column length. RESULTS Here we observe a strong linear relationship between tension and squared SWV across the preclinical sub-studies. Higher tension induces faster shear waves in the simulation (R2 = 0.984) and cadaveric (R2 = 0.951) models. The SWV decreases in all neurosurgical procedures (p < 0.001). Moreover, TAUT has a c-statistic of 0.962 (0.92-1.00), detecting all tethered cords. CONCLUSIONS This study presents a physical, clinical metric of spinal cord tension. Strong agreement among computational, cadaveric, and clinical studies demonstrates the utility of ultrasound-induced SWV for quantitative intraoperative feedback. This technology is positioned to enhance tethered cord diagnosis, treatment, and postoperative monitoring as it differentiates stretched from healthy cords.
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Affiliation(s)
- Max J Kerensky
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- HEPIUS Innovation Laboratory, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Abhijit Paul
- Discipline of Biological Engineering, Indian Institute of Technology Gandhinagar, Gujarat, India
| | - Denis Routkevitch
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- HEPIUS Innovation Laboratory, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Andrew M Hersh
- HEPIUS Innovation Laboratory, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Kelley M Kempski Leadingham
- HEPIUS Innovation Laboratory, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - A Daniel Davidar
- HEPIUS Innovation Laboratory, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Brendan F Judy
- Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Joshua Punnoose
- HEPIUS Innovation Laboratory, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Autumn Williams
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Avisha Kumar
- HEPIUS Innovation Laboratory, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Kurt Lehner
- Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Beth Smith
- HEPIUS Innovation Laboratory, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Jennifer K Son
- HEPIUS Innovation Laboratory, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Javad R Azadi
- HEPIUS Innovation Laboratory, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Himanshu Shekhar
- Discipline of Electrical Engineering, Indian Institute of Technology Gandhinagar, Gujarat, India
| | - Karla P Mercado-Shekhar
- Discipline of Biological Engineering, Indian Institute of Technology Gandhinagar, Gujarat, India
| | - Nitish V Thakor
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- HEPIUS Innovation Laboratory, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, MD, USA
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Nicholas Theodore
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- HEPIUS Innovation Laboratory, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Orthopaedic Surgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Amir Manbachi
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
- HEPIUS Innovation Laboratory, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
- Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
- Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, MD, USA.
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD, USA.
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Xu H, Feng Q, Ma X, Lan J, Ji J, Zhang Z, Miao J. Biomechanical behaviour of a novel bone cement screw in the minimally invasive treatment of Kummell's disease: a finite element study. BMC Musculoskelet Disord 2023; 24:967. [PMID: 38098003 PMCID: PMC10720208 DOI: 10.1186/s12891-023-07090-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Accepted: 12/02/2023] [Indexed: 12/18/2023] Open
Abstract
OBJECTIVE To investigate and evaluate the biomechanical behaviour of a novel bone cement screw in the minimally invasive treatment of Kummell's disease (KD) by finite element (FE) analysis. METHODS A validated finite element model of healthy adult thoracolumbar vertebrae T12-L2 was given the osteoporotic material properties and the part of the middle bone tissue of the L1 vertebral body was removed to make it wedge-shaped. Based on these, FE model of KD was established. The FE model of KD was repaired and treated with three options: pure percutaneous vertebroplasty (Model A), novel unilateral cement screw placement (Model B), novel bilateral cement screw placement (Model C). Range of motion (ROM), maximum Von-Mises stress of T12 inferior endplate and bone cement, relative displacement of bone cement, and stress distribution of bone cement screws of three postoperative models and intact model in flexion and extension, as well as lateral bending and rotation were analyzed and compared. RESULTS The relative displacements of bone cement of Model B and C were similar in all actions studied, and both were smaller than that of Model A. The minimum value of relative displacement of bone cement is 0.0733 mm in the right axial rotation of Model B. The maximum Von-Mises stress in T12 lower endplate and bone cement was in Model C. The maximum Von-Mises stress of bone cement screws in Model C was less than that in Model B, and it was the most substantial in right axial rotation, which is 34%. There was no substantial difference in ROM of the three models. CONCLUSION The novel bone cement screw can effectively reduce the relative displacement of bone cement by improving the stability of local cement. Among them, novel unilateral cement screw placement can obtain better fixation effect, and the impact on the biomechanical environment of vertebral body is less than that of novel bilateral cement screw placement, which provides a reference for minimally invasive treatment of KD in clinical practice.
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Affiliation(s)
- Hanpeng Xu
- Tianjin Hospital, Tianjin University, Tianjin, China
- Department of Orthopaedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Qing Feng
- Tianjin Hospital, Tianjin University, Tianjin, China
| | - Xiang Ma
- Tianjin Hospital, Tianjin University, Tianjin, China
| | - Jie Lan
- Tianjin Hospital, Tianjin University, Tianjin, China
| | - Jingtao Ji
- Tianjin Hospital, Tianjin University, Tianjin, China
| | - Zepei Zhang
- Tianjin Hospital, Tianjin University, Tianjin, China
| | - Jun Miao
- Tianjin Hospital, Tianjin University, Tianjin, China.
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Pokorni AJ, Turbucz M, Kiss RM, Eltes PE, Lazary A. Comparison of anterior column reconstruction techniques after en bloc spondylectomy: a finite element study. Sci Rep 2023; 13:18767. [PMID: 37907570 PMCID: PMC10618450 DOI: 10.1038/s41598-023-45736-6] [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: 03/03/2023] [Accepted: 10/23/2023] [Indexed: 11/02/2023] Open
Abstract
Total en bloc spondylectomy (TES) effectively treats spinal tumors. The surgery requires a vertebral body replacement (VBR), for which several solutions were developed, whereas the biomechanical differences between these devices still need to be completely understood. This study aimed to compare a femur graft, a polyetheretherketone implant (PEEK-IMP-C), a titan mesh cage (MESH-C), and a polymethylmethacrylate replacement (PMMA-C) using a finite element model of the lumbar spine after a TES of L3. Several biomechanical parameters (rotational stiffness, segmental range of motion (ROM), and von Mises stress) were assessed to compare the VBRs. All models provided adequate initial stability by increasing the rotational stiffness and decreasing the ROM between L2 and L4. The PMMA-C had the highest stiffness for flexion-extension, lateral bending, and axial rotation (215%, 216%, and 170% of intact model), and it had the lowest segmental ROM in the instrumented segment (0.2°, 0.5°, and 0.7°, respectively). Maximum endplate stress was similar for PMMA-C and PEEK-IMP-C but lower for both compared to MESH-C across all loading directions. These results suggest that PMMA-C had similar or better primary spinal stability than other VBRs, which may be related to the larger contact surface and the potential to adapt to the patient's anatomy.
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Affiliation(s)
- Agoston Jakab Pokorni
- In Silico Biomechanics Laboratory, National Center for Spinal Disorders, Királyhágó St. 1-3, Budapest, 1126, Hungary
- School of PhD Studies, Semmelweis University, Budapest, Hungary
| | - Mate Turbucz
- In Silico Biomechanics Laboratory, National Center for Spinal Disorders, Királyhágó St. 1-3, Budapest, 1126, Hungary
- School of PhD Studies, Semmelweis University, Budapest, Hungary
| | - Rita Maria Kiss
- Department of Mechatronics, Optics and Mechanical Engineering Informatics, Faculty of Mechanical Engineering, Budapest University of Technology and Economics, Műegyetem Rkp. 3., Budapest, 1111, Hungary
| | - Peter Endre Eltes
- In Silico Biomechanics Laboratory, National Center for Spinal Disorders, Királyhágó St. 1-3, Budapest, 1126, Hungary.
- Department of Spine Surgery, Department of Orthopaedics, Semmelweis University, Budapest, Hungary.
| | - Aron Lazary
- In Silico Biomechanics Laboratory, National Center for Spinal Disorders, Királyhágó St. 1-3, Budapest, 1126, Hungary
- Department of Spine Surgery, Department of Orthopaedics, Semmelweis University, Budapest, Hungary
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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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