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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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Tai CL, Chen WP, Liu MY, Li YD, Tsai TT, Lai PL, Hsieh MK. Biomechanical comparison of pedicle screw fixation strength among three different screw trajectories using single vertebrae and one-level functional spinal unit. Front Bioeng Biotechnol 2022; 10:1054738. [PMID: 36568298 PMCID: PMC9780459 DOI: 10.3389/fbioe.2022.1054738] [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: 09/27/2022] [Accepted: 11/29/2022] [Indexed: 12/14/2022] Open
Abstract
Three key factors are responsible for the biomechanical performance of pedicle screw fixation: screw mechanical characteristics, bone quality and insertion techniques. To the best of the authors' knowledge, no study has directly compared the biomechanical performance among three trajectories, i.e., the traditional trajectory (TT), modified trajectory (MT) and cortical bone trajectory (CBT), in a porcine model. This study compared the pullout strength and insertion torque of three trajectory methods in single vertebrae, the pullout strength and fixation stiffness including flexion, extension, and lateral bending in a one-level instrumented functional spinal unit (FSU) that mimics the in vivo configuration were clarified. A total of 18 single vertebrae and 18 FSUs were randomly assigned into three screw insertion methods (n = 6 in each trajectory group). In the TT group, the screw converged from its entry point, passed completely inside the pedicle, was parallel to the superior endplate, was located in the superior third of the vertebral body and reached to at least the anterior third of the vertebral body. In the MT group, the convergent angle was similar to that of the TT method but directed caudally to the anterior inferior margin of the vertebral body. The results of insertion torque and pullout strength in single vertebrae were analyzed; in addition, the stiffness and pullout strength in the one-level FSU were also investigated. This study demonstrated that, in single vertebrae, the insertion torque was significantly higher in CBT groups than in TT and MT groups (p < 0.05). The maximal pullout strength was significantly higher in MT groups than in TT and CBT groups (p < 0.05). There was no significant difference in stiffness in the three motions among all groups. The maximal pullout strength in FSUs of MT and CBT groups were significantly higher than the TT groups (p < 0.05). We concluded that either MT or CBT provides better biomechanical performance than TT in single vertebrae or FSUs. The lack of significance of stiffness in FSUs among three methods suggested that MT or CBT could be a reasonable alternative to TT if the traditional trajectory was not feasible.
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Affiliation(s)
- Ching-Lung Tai
- Department of Biomedical Engineering, Chang Gung University, Taoyuan, Taiwan,Department of Orthopaedic Surgery, Spine Section, Bone and Joint Research Center, Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Taoyuan, Taiwan
| | - Weng-Pin Chen
- Department of Mechanical Engineering, National Taipei University of Technology, Taipei, Taiwan
| | - Mu-Yi Liu
- Department of Biomedical Engineering, Chang Gung University, Taoyuan, Taiwan
| | - Yun-Da Li
- Department of Biomedical Engineering, Chang Gung University, Taoyuan, Taiwan,Department of Orthopaedic Surgery, Spine Section, Bone and Joint Research Center, Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Taoyuan, Taiwan
| | - 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, Taiwan
| | - 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, Taiwan
| | - 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, Taiwan,*Correspondence: Ming-Kai Hsieh,
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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: 1] [Impact Index Per Article: 0.5] [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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Mirzaei F, Iranmehr A, Shokouhi G, Khadivi M, Shakeri M, Namvar M, Rafiei E, Matloubi B. The role of cross-link augmentation on fusion rate and patient satisfaction among patients with traumatic thoracolumbar spinal fracture: A randomized clinical trial. NEUROCIRUGIA (ENGLISH EDITION) 2022; 33:105-110. [PMID: 35526942 DOI: 10.1016/j.neucie.2021.01.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Accepted: 01/04/2021] [Indexed: 06/14/2023]
Abstract
INTRODUCTION AND OBJECTIVES Most of the studies evaluating the effect of cross links on spinal stability are performed in vitro on porcine or human spine segments and there is limited data regarding clinical benefits of cross link augmentation in traumatic injuries. In this study we aimed to evaluate the effects of cross-links insertion between rods on the fusion rates and post-surgical patients' satisfaction among patients with traumatic thoracolumbar fractures who underwent posterior spinal fixation with pedicle screws. MATERIALS AND METHODS This study was conducted as a randomized clinical trial on 60 patients suffering from traumatic thoracolumbar vertebrae fractures. Patients were randomized into three groups: A (without any cross-link), B (One cross-link insertion) and C (two cross-links insertion). Six months after surgery outcomes were evaluated: fusion rates (plain X-ray and CT scan), Back pain (Visual Analog Scale) and patient satisfaction (fair, good, excellent). RESULTS In group A 13 (65%) patients had structured bone fusion, but in 7 (35%) patients bone fusion was not observed. In both groups B and C, 19 patients (95%) had bone fusion, but only in 1 patient (5%) fusion failed (p=0.009). In group A, fair satisfaction has the highest rate (8 patients (40%)) compared to the other groups. The highest reported severity of back pain was observed in group A while the lowest reported intensity of back pain was related to group B (p=0.001). CONCLUSIONS Adding cross link to posterior spinal fixations of patients with traumatic thoracolumbar fractures can be associated with better final fusion results and patients' satisfaction. However it is necessary to design studies with greater sample sizes to confirm this theory. TRIAL REGISTRATION NUMBER IRCT20120527009878N3.
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Affiliation(s)
- Farhad Mirzaei
- Department of Neurosurgery, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Arad Iranmehr
- Department of Neurosurgery, Tehran University of Medical Sciences, Tehran, Iran
| | - Ghaffar Shokouhi
- Department of Neurosurgery, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Masoud Khadivi
- Department of Neurosurgery, Tehran University of Medical Sciences, Tehran, Iran
| | - Moslem Shakeri
- Department of Neurosurgery, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Mohamad Namvar
- Department of Neurosurgery, Tehran University of Medical Sciences, Tehran, Iran.
| | - Ebrahim Rafiei
- Department of Neurosurgery, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Bagher Matloubi
- Department of Neurosurgery, Tabriz University of Medical Sciences, Tabriz, Iran
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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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Mirzaei F, Iranmehr A, Shokouhi G, Khadivi M, Shakeri M, Namvar M, Rafiei E, Matloubi B. The role of cross-link augmentation on fusion rate and patient satisfaction among patients with traumatic thoracolumbar spinal fracture: A randomized clinical trial. Neurocirugia (Astur) 2021; 33:S1130-1473(21)00011-7. [PMID: 33676794 DOI: 10.1016/j.neucir.2021.01.002] [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: 10/02/2020] [Revised: 12/16/2020] [Accepted: 01/04/2021] [Indexed: 10/22/2022]
Abstract
INTRODUCTION AND OBJECTIVES Most of the studies evaluating the effect of cross links on spinal stability are performed in vitro on porcine or human spine segments and there is limited data regarding clinical benefits of cross link augmentation in traumatic injuries. In this study we aimed to evaluate the effects of cross-links insertion between rods on the fusion rates and post-surgical patients' satisfaction among patients with traumatic thoracolumbar fractures who underwent posterior spinal fixation with pedicle screws. MATERIALS AND METHODS This study was conducted as a randomized clinical trial on 60 patients suffering from traumatic thoracolumbar vertebrae fractures. Patients were randomized into three groups: A (without any cross-link), B (One cross-link insertion) and C (two cross-links insertion). Six months after surgery outcomes were evaluated: fusion rates (plain X-ray and CT scan), Back pain (Visual Analog Scale) and patient satisfaction (fair, good, excellent). RESULTS In group A 13 (65%) patients had structured bone fusion, but in 7 (35%) patients bone fusion was not observed. In both groups B and C, 19 patients (95%) had bone fusion, but only in 1 patient (5%) fusion failed (p=0.009). In group A, fair satisfaction has the highest rate (8 patients (40%)) compared to the other groups. The highest reported severity of back pain was observed in group A while the lowest reported intensity of back pain was related to group B (p=0.001). CONCLUSIONS Adding cross link to posterior spinal fixations of patients with traumatic thoracolumbar fractures can be associated with better final fusion results and patients' satisfaction. However it is necessary to design studies with greater sample sizes to confirm this theory. TRIAL REGISTRATION NUMBER IRCT20120527009878N3.
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Affiliation(s)
- Farhad Mirzaei
- Department of Neurosurgery, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Arad Iranmehr
- Department of Neurosurgery, Tehran University of Medical Sciences, Tehran, Iran
| | - Ghaffar Shokouhi
- Department of Neurosurgery, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Masoud Khadivi
- Department of Neurosurgery, Tehran University of Medical Sciences, Tehran, Iran
| | - Moslem Shakeri
- Department of Neurosurgery, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Mohamad Namvar
- Department of Neurosurgery, Tehran University of Medical Sciences, Tehran, Iran.
| | - Ebrahim Rafiei
- Department of Neurosurgery, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Bagher Matloubi
- Department of Neurosurgery, Tabriz University of Medical Sciences, Tabriz, Iran
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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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Du YQ, Li T, Ma C, Qiao GY, Yin YH, Yu XG. Biomechanical evaluation of two alternative techniques to the Goel-Harms technique for atlantoaxial fixation: C1 lateral mass-C2 bicortical translaminar screw fixation and C1 lateral mass-C2/3 transarticular screw fixation. J Neurosurg Spine 2020; 32:682-688. [PMID: 31952043 DOI: 10.3171/2019.11.spine191178] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Accepted: 11/11/2019] [Indexed: 11/06/2022]
Abstract
OBJECTIVE The authors conducted a study to investigate the biomechanical feasibility and stability of C1 lateral mass-C2 bicortical translaminar screw (C1LM-C2TL) fixation, C1 lateral mass-C2/3 transarticular screw (C1LM-C2/3TA) fixation, and C1LM-C2/3TA fixation with transverse cross-links (C1LM-C2/3TACL) as alternative techniques to the Goel-Harms technique (C1 lateral mass-C2 pedicle screw [C1LM-C2PS] fixation) for atlantoaxial fixation. METHODS Eight human cadaveric cervical spines (occiput-C7) were tested using an industrial robot. Pure moments that were a maximum of 1.5 Nm were applied in flexion-extension (FE), lateral bending (LB), and axial rotation (AR). The specimens were first tested in the intact state and followed by destabilization (a type II odontoid fracture) and fixation as follows: C1LM-C2PS, C1LM-C2TL, C1LM-C2/3TA, and C1LM-C2/3TACL. For each condition, the authors evaluated the range of motion and neutral zone across C1 and C2 in all directions. RESULTS Compared with the intact spine, each instrumented spine significantly increased in stability at the C1-2 segment. C1LM-C2TL fixation demonstrated similar stability in FE and LB and greater stability in AR than C1LM-C2PS fixation. C1LM-C2/3TA fixation was equivalent in LB and superior in FE to those of C1LM-C2PS and C1LM-C2TL fixation. During AR, the C1LM-C2/3TA-instrumented spine failed to maintain segmental stability. After adding a cross-link, the rotational stability was significantly increased in the C1LM-C2/3TACL-instrumented spine compared with the C1LM-C2/3TA-instrumented spine. Although inferior to C1LM-C2TL fixation, the C1LM-C2/3TACL-instrumented spine showed equivalent rotational stability to the C1LM-C2PS-instrumented spine. CONCLUSIONS On the basis of our biomechanical study, C1LM-C2TL and C1LM-C2/3TACL fixation resulted in satisfactory atlantoaxial stabilization compared with C1LM-C2PS. Therefore, the authors believe that the C1LM-C2TL and C1LM-C2/3TACL fixation may serve as alternative procedures when the Goel-Harms technique (C1LM-C2PS) is not feasible due to anatomical constraints.
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Affiliation(s)
- Yue-Qi Du
- 1Department of Neurosurgery, Chinese PLA General Hospital, Beijing; and
| | - Teng Li
- 1Department of Neurosurgery, Chinese PLA General Hospital, Beijing; and
| | - Chao Ma
- 2Key Laboratory of Modern Measurement and Control Technology, Ministry of Education, Beijing Information Science and Technology University, Beijing, China
| | - Guang-Yu Qiao
- 1Department of Neurosurgery, Chinese PLA General Hospital, Beijing; and
| | - Yi-Heng Yin
- 1Department of Neurosurgery, Chinese PLA General Hospital, Beijing; and
| | - Xin-Guang Yu
- 1Department of Neurosurgery, Chinese PLA General Hospital, Beijing; and
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Biomechanical Analysis of a Growing Rod with Sliding Pedicle Screw System for Early-Onset Scoliosis. JOURNAL OF HEALTHCARE ENGINEERING 2019; 2019:9535070. [PMID: 31281619 PMCID: PMC6594281 DOI: 10.1155/2019/9535070] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Accepted: 03/25/2019] [Indexed: 01/21/2023]
Abstract
Early-onset scoliosis (EOS) remains a challenging condition for which current nonfusion surgeries require iterative lengthening surgeries. A growing rod with sliding pedicle screw system (GRSPSS) was developed to treat spinal deformities without repeated operative lengthening. This study was performed to evaluate whether GRSPSS had similar stability as a conventional pedicle screw system to maintain deformity correction. A serial-linkage robotic manipulator with a six-axis load cell positioned on the end-effector was utilized to evaluate the mechanical stability of the GRSPSS versus conventional fixed scoliosis instrumentation. Ten skeletally mature thoracic female Katahdin sheep spines (T4-L1) were subjected to 2.5 Nm of flexion-extension (FE), lateral bending (LB), and axial rotation (AR) in 2° increments for each state. The overall range of motion (ROM), apical segment ROM, and stiffness were calculated and reported. A two-tailed paired t-test was used to detect significant differences (p < 0.05) between the fixed group and GRSPSS fixation. There were no significant differences in overall range of motion (ROM), apical segment ROM, or stiffness for FE or LB between the GRSPSS group and fixed group. In AR, the GRSPSS group showed increased ROM compared to the fixed group for the overall spine (36.0° versus 19.2°, p < 0.01) and for the instrumented T8-T10 segments (7.0° versus 2.9°, p=0.02). Similarly, the fixed rod elastic zone (EZ) stiffness was significantly greater than the GRSPSS EZ stiffness (0.29 N/m versus 0.17 N/m, p < 0.001). The space around the rod allows for the increased AR observed with the GRSPSS fusion technique and is necessary for axial growth. The GRSPSS fusion model shows equivalent flexion and LB stability to current fusion models and represents a stable fusion technique and may allow for longitudinal growth during childhood.
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Rustenburg CME, Faraj SSA, Holewijn RM, Kingma I, van Royen BJ, Stadhouder A, Emanuel KS. The biomechanical effect of single-level laminectomy and posterior instrumentation on spinal stability in degenerative lumbar scoliosis: a human cadaveric study. Neurosurg Focus 2019; 46:E15. [PMID: 31042658 DOI: 10.3171/2019.2.focus1911] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Accepted: 02/06/2019] [Indexed: 11/06/2022]
Abstract
OBJECTIVEDegenerative lumbar scoliosis, or de novo degenerative lumbar scoliosis, can result in spinal canal stenosis, which is often accompanied by disabling symptoms. When surgically treated, a single-level laminectomy is performed and short-segment posterior instrumentation is placed to restore stability. However, the effects of laminectomy on spinal stability and the necessity of placing posterior instrumentation are unknown. Therefore, the aim of this study was to assess the stability of lumbar spines with degenerative scoliosis, characterized by the range of motion (ROM) and neutral zone (NZ) stiffness, after laminectomy and placement of posterior instrumentation.METHODSTen lumbar cadaveric spines (T12-L5) with a Cobb angle ≥ 10° and an apex on L3 were included. Three loading cycles were applied per direction, from -4 Nm to 4 Nm in flexion/extension (FE), lateral bending (LB), and axial rotation (AR). Biomechanical evaluation was performed on the native spines and after subsequent L3 laminectomy and the placement of posterior L2-4 titanium rods and pedicle screws. Nonparametric and parametric tests were used to analyze the effects of laminectomy and posterior instrumentation on NZ stiffness and ROM, respectively, both on an individual segment's motion and on the entire spine section. Spearman's rank correlation coefficient was used to study the correlation between disc degeneration and spinal stability.RESULTSThe laminectomy increased ROM by 9.5% in FE (p = 0.04) and 4.6% in LB (p = 0.01). For NZ stiffness, the laminectomy produced no significant effects. Posterior instrumentation resulted in a decrease in ROM in all loading directions (-22.2%, -24.4%, and -17.6% for FE, LB, and AR, respectively; all p < 0.05) and an increase in NZ stiffness (+44.7%, +51.7%, and +35.2% for FE, LB, and AR, respectively; all p < 0.05). The same changes were seen in the individual segments around the apex, while the adjacent, untreated segments were mostly unaffected. Intervertebral disc degeneration was found to be positively correlated to decreased ROM and increased NZ stiffness.CONCLUSIONSLaminectomy in lumbar spines with degenerative scoliosis did not result in severe spinal instability, whereas posterior instrumentation resulted in a rigid construct. Also, prior to surgery, the spines already had lower ROM and higher NZ stiffness in comparison to values shown in earlier studies on nonscoliotic spines of the same age. Hence, the authors question the clinical need for posterior instrumentation to avoid instability.
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Affiliation(s)
| | - Sayf S A Faraj
- 2Department of Orthopedic Surgery, Radboud UMC, Nijmegen
| | | | - Idsart Kingma
- 4Amsterdam Movement Sciences, Faculty of Movement Sciences, Vrije Universiteit, Amsterdam; and
| | - Barend J van Royen
- 1Amsterdam Movement Sciences, Department of Orthopaedic Surgery, Amsterdam UMC, Amsterdam
| | - Agnita Stadhouder
- 1Amsterdam Movement Sciences, Department of Orthopaedic Surgery, Amsterdam UMC, Amsterdam
| | - Kaj S Emanuel
- 1Amsterdam Movement Sciences, Department of Orthopaedic Surgery, Amsterdam UMC, Amsterdam.,5Department of Orthopaedic Surgery, Maastricht UMC+, Maastricht, The Netherlands
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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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Shen K, Tan Z, Yang F, Zhang S, Cao D. [Common pedicle screw placement under direct vision combined with dome shaped decompression via small incision for double segment thoracolumbar fracture with nerve injury]. ZHONGGUO XIU FU CHONG JIAN WAI KE ZA ZHI = ZHONGGUO XIUFU CHONGJIAN WAIKE ZAZHI = CHINESE JOURNAL OF REPARATIVE AND RECONSTRUCTIVE SURGERY 2017; 31:677-682. [PMID: 29798648 PMCID: PMC8498298 DOI: 10.7507/1002-1892.201701092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Revised: 04/18/2017] [Indexed: 11/03/2022]
Abstract
Objective To determine the feasibility, safety, and efficacy of common pedicle screw placement under direct vision combined with dome shaped decompression via small incision for double segment thoracolumbar fracture with nerve injury. Methods A retrospective analysis was performed on the clinical data of 32 patients with double segment thoracolumbar fracture with nerve injury undergoing common pedicle screw placement under direct vision combined with dome shaped decompression via small incision between November 2011 and November 2015 (combined surgery group), and another 32 patients undergoing traditional open pedicle screw fixation surgery (traditional surgery group). There was no significant difference in gender, age, cause of injury, time of injury-to-surgery, injury segments and Frankel classification of neurological function between two groups ( P>0.05). The length of soft tissue dissection, the operative time, the blood loss during surgery, the postoperative drainage, the visual analogue scale (VAS) of incision after surgery, and recovery of neurological function after surgery were evaluated. Results All cases were followed up 9 to 12 months (mean, 10.5 months) in combined surgery group, and 8 to 12 months (mean, 9.8 months) in traditional surgery group. The length of soft tissue dissection, the operative time, the blood loss during surgery, the postoperative drainage, and the postoperative VAS score in the combined surgery group were significantly better than those in the traditional surgery group ( P<0.05). Dural rupture during surgery and pedicle screw pulling-out at 6 months after surgery occurred in 2 cases and 1 case of the combined surgery group; dural rupture during surgery occurred in 1 case of the traditional surgery group. The X-ray films showed good decompression, and fracture healing; A certain degree of neurological function recovery was achieved in two groups. Conclusion Common pedicle screw placement under direct vision combined with dome shaped decompression via small incision can significantly reduce iatrogenic trauma and provide good nerve decompression. Therefore, it is a safe, effective, and minimally invasive treatment method for double segment thoracolumbar fracture with neurological injury.
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Affiliation(s)
- Kai Shen
- Department of Spine Surgery, Chongqing General Hospital, Chongqing, 400013, P.R.China
| | - Zujian Tan
- Department of Spine Surgery, Chongqing General Hospital, Chongqing, 400013,
| | - Fubin Yang
- Department of Spine Surgery, Chongqing General Hospital, Chongqing, 400013, P.R.China
| | - Shengli Zhang
- Department of Spine Surgery, Chongqing General Hospital, Chongqing, 400013, P.R.China
| | - Daigui Cao
- Department of Spine Surgery, Chongqing General Hospital, Chongqing, 400013, P.R.China
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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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Biomechanical Analysis of a Pedicle Screw-Rod System with a Novel Cross-Link Configuration. Asian Spine J 2016; 10:993-999. [PMID: 27994773 PMCID: PMC5165013 DOI: 10.4184/asj.2016.10.6.993] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Revised: 04/05/2016] [Accepted: 04/08/2016] [Indexed: 11/08/2022] Open
Abstract
Study Design The strength effects of a pedicle screw-rod system supplemented with a novel cross-link configuration were biomechanically evaluated in porcine spines. Purpose To assess the biomechanical differences between a conventional cross-link pedicle screw-rod system versus a novel cross-link instrumentation, and to determine the effect of the cross-links. Overview of Literature Transverse cross-link systems affect torsional rigidity, but are thought to have little impact on the sagittal motion of spinal constructs. We tested the strength effects in pullout and flexion-compression tests of novel cross-link pedicle screw constructs using porcine thoracic and lumbar vertebrae. Methods Five matched thoracic and lumbar vertebral segments from 15 porcine spines were instrumented with 5.0-mm pedicle screws, which were then connected with 6.0-mm rods after partial corpectomy in the middle vertebral body. The forces required for construct failure in pullout and flexion-compression tests were examined in a randomized manner for three different cross-link configurations: un-cross-link control, conventional cross-link, and cross-link passing through the base of the spinous process. Statistical comparisons of strength data were analyzed using Student's t-tests. Results The spinous process group required a significantly greater pullout force for construct failure than the control group (p=0.036). No difference was found between the control and cross-link groups, or the cross-link and spinous process groups in pullout testing. In flexion-compression testing, the spinous processes group required significantly greater forces for construct failure than the control and cross-link groups (p<0.001 and p=0.003, respectively). However, there was no difference between the control and cross-link groups. Conclusions A novel cross-link configuration that features cross-link devices passing through the base of the spinous processes increased the mechanical resistance in pullout and flexion-compression testing compared to un-cross-link constructs. This configuration provided more resistance to middle-column damage under flexion-compression testing than conventional cross-link configuration.
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Brooks JT, Jain A, Sanchez-Perez-Grueso F, Skaggs DL, Thompson GH, Akbarnia BA, Sponseller PD. Outcomes of Pelvic Fixation in Growing Rod Constructs: An Analysis of Patients With a Minimum of 4 Years of Follow-up. Spine Deform 2016; 4:211-216. [PMID: 27927505 DOI: 10.1016/j.jspd.2015.11.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Revised: 10/16/2015] [Accepted: 11/24/2015] [Indexed: 10/21/2022]
Abstract
STUDY DESIGN Retrospective review. OBJECTIVE To evaluate which distal anchors in growing rod (GR) constructs optimally correct major curve, pelvic obliquity, sagittal alignment, T1-S1 length, thoracic kyphosis, and lumbar lordosis with the fewest complications at 4 or more years' postoperative follow-up. SUMMARY OF BACKGROUND DATA Pelvic fixation to the ilium and/or sacrum in GR constructs is used to treat patients with early-onset scoliosis. No studies have evaluated radiographical outcomes and complications in these patients at 4 or more years' follow-up. METHODS Included were 38 patients from a multicenter early-onset-scoliosis database with dual GRs anchored to the pelvis. Radiographic data included major curve, T1-S1 length, T5-T12 kyphosis, lordosis, sagittal alignment, and pelvic obliquity at preoperative and latest follow-up time points. Complications were evaluated for all anchor subtypes. RESULTS Mean follow-up time was 5.3 ± 0.1 years. GRs with distal anchors to the ilium significantly improved major curve (49%, p = .013) and pelvic obliquity (78%, p = .035) compared with constructs anchored to the sacrum only. Constructs with iliac fixation with S1 screws provided greater correction of lumbar kyphosis than constructs with iliac fixation and no S1 screws (p = .023). Constructs with a single caudal crosslink had a greater T1-S1 length at latest follow-up than constructs with combined cephalad and caudal crosslinks (p = .027). There were no significant differences in the rates of infection or instrumentation failure between iliac and sacral fixation groups. GR constructs with distal anchors that used a posterior superior iliac spine start point had a higher infection rate (60%) than those inserted via a sacral-alar-iliac technique (7%) (p = .002). CONCLUSIONS GR constructs anchored to the ilium provide significant improvements in the major curve and pelvic obliquity at a minimum of 4 years of follow-up versus constructs anchored to the sacrum alone. LEVEL OF EVIDENCE Level III, retrospective cohort study.
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Affiliation(s)
- Jaysson T Brooks
- Department of Orthopaedic Surgery, The Johns Hopkins University, 601 N Caroline St, Baltimore, MD 21231, USA
| | - Amit Jain
- Department of Orthopaedic Surgery, The Johns Hopkins University, 601 N Caroline St, Baltimore, MD 21231, USA
| | | | - David L Skaggs
- Children's Orthopedic Center, Children's Hospital Los Angeles, 4650 Sunset Blvd, MS #69, Los Angeles, CA 90027, USA
| | - George H Thompson
- Division of Pediatric Orthopaedic Surgery, Rainbow Babies & Children's Hospital, Case Western Reserve University, 11100 Euclid Ave, Cleveland, OH 44106, USA
| | - Behrooz A Akbarnia
- Department of Orthopaedic Surgery, University of California-San Diego, 200 West Arbor Dr, San Diego, CA 92103, USA; San Diego Center for Spinal Disorders, 6190 Cornerstone Ct, Ste 212, San Diego, CA 92121, USA
| | - Paul D Sponseller
- Department of Orthopaedic Surgery, The Johns Hopkins University, 601 N Caroline St, Baltimore, MD 21231, USA.
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Motizuki H, Graells XS, Zaninelli EM, Benato ML, Sonagli MA. TREATMENT OF THORACOLUMBAR BURST FRACTURES FIXED WITH INTERMEDIATE PINS BY THE POSTERIOR APPROACH. COLUNA/COLUMNA 2015. [DOI: 10.1590/s1808-185120151403054255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/03/2023] Open
Abstract
Objective:Radiographic evaluation of patients with thoracolumbar burst fractures treated with unconvencional transpedicular fixation, which includes additional fixation of the fractured vertebra associated with transverse connector - Crosslink clamp.Methods:Retrospective study evaluating a total of 68 patients operated at the Hospital do Trabalhador de Curitiba, Orthopedics Service, of which 15 were eligible for the study. All patients were treated with posterior pedicle fixation and intermediate screw. The assessment by the Cobb angle method was performed on preoperative, immediate postoperative and one year after surgery radiographs.Results:It was observed an average reduction of kyphosis of 8.3o (77%), with a loss of 1.34o in late postoperative compared to the immediate postoperative period.Conclusion:The method of fixation of burst-type fractures of the thoracolumbar spine by the posterior approach with intermediate screw was effective in maintaining the reduction achieved in the immediate postoperative period and after one year of evolution.
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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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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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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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Mechanical behavior of a novel non-fusion scoliosis correction device. J Mech Behav Biomed Mater 2013; 27:107-14. [DOI: 10.1016/j.jmbbm.2013.07.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2013] [Revised: 06/28/2013] [Accepted: 07/04/2013] [Indexed: 11/23/2022]
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Charles YP, Lima LVPC, Persohn S, Rouch P, Steib JP, Skalli W. Influence of an auxiliary facet system on intervertebral discs and adjacent facet joints. Spine J 2013; 13:1293-300. [PMID: 23988459 DOI: 10.1016/j.spinee.2013.06.019] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/29/2012] [Revised: 11/16/2012] [Accepted: 06/01/2013] [Indexed: 02/03/2023]
Abstract
BACKGROUND CONTEXT Facet supplementation stabilizes after facetectomy and undercutting laminectomy. It is indicated in degenerative spondylolisthesis with moderate disc degeneration and dynamic stenosis. PURPOSE To determine the influence of an auxiliary facet system (AFS) on the instrumented disc, adjacent levels' discs, and facet joints and to compare it with fusion. STUDY DESIGN Finite element study. METHODS L3-L4, L4-L5, and L5-S1 were studied using a validated finite element model with prescribed displacements for an intact spine, lesion by facetectomy and undercutting laminectomy, AFS, and fusion at L4-L5. The distribution of segmental range of motion (ROM) and applied moments, von Mises stress at the annulus, and facet joint contact forces were calculated with rotations in all planes. Institutional support for implant evaluation and modeling was received by Clariance. RESULTS In flexion-extension and lateral bending, fusion decreased L4-L5 ROM and increased adjacent levels' ROM. Range of motion was similarly distributed with intact lesion and AFS. In axial rotation, L4-L5 ROM represented 33% with intact, 55% after lesion, 25% with AFS, and 21% with fusion. Fusion increased annulus stress at adjacent levels in flexion-extension and lateral bending, but decreased stress at L4-L5 compared with AFS. In axial rotation, von Mises stress was similar with fusion and AFS. Facet loading increased in extension and lateral bending with fusion. It was comparable for fusion and AFS in axial rotation. CONCLUSIONS This study suggests that the AFS stabilizes L4-L5 in axial rotation after facetectomy and undercutting laminectomy as fusion does. This is because of the cross-link that generates an increased annulus stress in axial rotation at adjacent levels. With imposed displacements, without in vivo compensation of the hips, the solicitation at adjacent levels' discs and facet joints is higher with fusion compared with AFS. Fusion decreases intradiscal stress at the instrumented level.
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Affiliation(s)
- Yann Philippe Charles
- Laboratoire de Biomécanique, Arts et Métiers ParisTech, Paris, France; Service de Chirurgie du Rachis, Hôpitaux Universitaires de Strasbourg, Fédération de Médecine Translationnelle, Université de Strasbourg, 1, Place de l'hôpital, B.P. 426, 67091 Strasbourg Cedex, France.
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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: 35] [Impact Index Per Article: 3.2] [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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Abstract
Pedicle screws have become the gold standard of spinal instrumentation over the past decade owing to their biomechanical superiority. Despite their advantages, pedicle screw instrumentation is potentially dangerous, and surgeons wish to improve accuracy of screw placement to avoid complications associated with screw misplacement. The anatomy of the pedicles is variable throughout the spine, and several landmarks and trajectories have been suggested to aid safe placement of pedicle screws in the spine. Several techniques such as x-ray and computed tomography scan imaging coupled with computer-aided navigation are available to improve accuracy of screw insertion. Intraoperative neuromonitoring with the help of triggered electromyographic recordings has evolved as an objective evidence of assessing pedicle breach and proximity of the screw to neural structures. While all imaging and electrophysiological modalities should be applied on an individualized basis, finally no adjunctive technique can fully replace the need for surgical expertise and experience.
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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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Sonagli MA, Graells XSI, Negrisoli MDB, Sonagli M, Benato ML, Zaninelli EM, Oliveira LYSD, Cunha LAMD. Estudo biomecânico da fixação pedicular curta na fratura-explosão toracolombar. COLUNA/COLUMNA 2011. [DOI: 10.1590/s1808-18512011000300003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
OBJETIVO: Comparar a rigidez biomecânica entre a coluna toracolombar intacta, a coluna com fratura explosão e a coluna com fratura explosão associada à fixação pedicular curta em suínos. MÉTODOS: 30 amostras de coluna toracolombar (T11-L3) de suínos foram divididas em três grupos com 10 amostras cada. O Grupo 1 representava a coluna intacta, o Grupo 2 representava a coluna com fratura explosão e o Grupo 3 a fratura explosão associada à fixação pedicular curta. Foi realizado o corte ósseo em "V" do terço médio do corpo vertebral comprometendo a coluna anterior e média de L1 para simular a fratura explosão. No Grupo 3 foi realizada a fixação pedicular com Pinos de Schanz. Os grupos foram submetidos ao teste biomecânico em compressão axial controlada. Os parâmetros de carga (N) e deslocamento (mm) eram gerados em um gráfico instantâneo e a rigidez (N/mm) foi determinada. O teste era interrompido quando ocorria uma queda súbita na curva no gráfico indicando falência da amostra. RESULTADOS: A rigidez das colunas fraturadas foi 53% menor do que a rigidez das colunas intactas, sendo essa diferença estatisticamente significativa (p < 0,05). A fixação pedicular curta apresentou uma rigidez 50% maior do que a coluna fraturada. Esse aumento foi estatisticamente significativo (p < 0,05). A rigidez da fixação pedicular curta foi 30% menor do que a rigidez das colunas intactas. Essas diferenças foram estatisticamente significativas (p < 0,05). CONCLUSÃO: A fixação pedicular curta não é suficiente para restabelecer a rigidez da coluna intacta nos testes biomecânicos in vitro de compressão axial pura em modelos de fratura toracolombar de suínos.
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Hankinson TC, Avellino AM, Harter D, Jea A, Lew S, Pincus D, Proctor MR, Rodriguez L, Sacco D, Spinks T, Brockmeyer DL, Anderson RCE. Equivalence of fusion rates after rigid internal fixation of the occiput to C-2 with or without C-1 instrumentation. J Neurosurg Pediatr 2010; 5:380-4. [PMID: 20367344 DOI: 10.3171/2009.10.peds09296] [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: 01/09/2023]
Abstract
OBJECT The object of this study was to assess a multiinstitutional experience with pediatric occipitocervical constructs to determine whether a difference exists between the fusion and complication rates of constructs with or without direct C-1 instrumentation. METHODS Seventy-seven cases of occiput-C2 instrumentation and fusion, performed at 9 children's hospitals, were retrospectively analyzed. Entry criteria included atlantooccipital instability with or without atlantoaxial instability. Any case involving subaxial instability was excluded. Constructs were divided into 3 groups based on the characteristics of the anchoring spinal instrumentation: Group 1, C-2 instrumentation; Group 2, C-1 and C-2 instrumentation without transarticular screw (TAS) placement; and Group 3, any TAS placement. Groups were compared based on rates of fusion and perioperative complications. RESULTS Group 1 consisted of 16 patients (20.8%) and had a 100% rate of radiographically demonstrated fusion. Group 2 included 22 patients (28.6%), and a 100% fusion rate was achieved, although 2 cases were lost to follow-up before documented fusion. Group 3 included 39 patients (50.6%) and demonstrated a 100% radiographic fusion rate. Complication rates were 12.5, 13.7, and 5.1%, respectively. There were 3 vertebral artery injuries, 1 (4.5%) in Group 2 and 2 (5.1%) in Group 3. CONCLUSIONS High fusion rates and low complication rates were achieved with each configuration examined. There was no difference in fusion rates between the group without (Group 1) and those with (Groups 2 and 3) C-1 instrumentation. These findings indicated that in the pediatric population, excellent occipitocervical fusion rates can be accomplished without directly instrumenting C-1.
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Affiliation(s)
- Todd C Hankinson
- Department of Neurosurgery, College of Physicians and Surgeons, Columbia University, New York, New York 10032, USA.
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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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Risk factors and outcomes for catastrophic failures at the top of long pedicle screw constructs: a matched cohort analysis performed at a single center. Spine (Phila Pa 1976) 2009; 34:2134-9. [PMID: 19713876 DOI: 10.1097/brs.0b013e3181b2e17e] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN Retrospective review with matched-cohort analysis performed at a single institution. OBJECTIVE To determine risk factors and outcomes for acute fractures at the proximal aspect of long pedicle screw constructs. SUMMARY OF BACKGROUND DATA Acute fractures at the top of long segmental pedicle screw constructs (FPSC) can be catastrophic. Substantial surgical increase in lordosis may precipitate this problem. In relation to a matched cohort, we postulated that age, body mass index (BMI), and significant correction of lumbar lordosis would increase risk of FPSC and patients with FPSC would have lesser improvements in outcomes. METHODS Thirteen patients who sustained FPSC between 2000 and 2007 were evaluated. During this time, 264 patients aged 40 or older had a spinal fusion from the thoracic spine to the sacrum using an all-pedicle screw construct. A cohort of 31 of these patients without FPSC but with all pedicle screw constructs was matched for diagnosis of positive sagittal imbalance, gender, preoperative C7 sagittal plumb, and number of levels fused. RESULTS There was a significant difference in age (P = 0.02) and BMI (P = 0.006) between the matched groups. There was no significant difference in preoperative/postoperative C7 plumb or change in lumbar lordosis between groups. Acute neurological deficit developed in 2 patients; both patients improved substantially after revision surgery. Nine patients underwent proximal extension of the fusion. For 7 of the 13 FPSC patients with bone mineral density data (BMD) available, average T score was-1.73; -0.58 for the matched group (10/31 with bone mineral density data) (P = 0.02). CONCLUSION Factors that increased the risk of FPSC included obesity and older age. Osteopenia increased the risk as evidenced by BMD (based on 17 patients) and the older age of these patients. There was no statistical difference in clinical improvement between groups based on ODI, but the FPSC group did demonstrate a smaller improvement in ODI score than the matched cohort.
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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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Finn MA, Fassett DR, Mccall TD, Clark R, Dailey AT, Brodke DS. The cervical end of an occipitocervical fusion: a biomechanical evaluation of 3 constructs. Laboratory investigation. J Neurosurg Spine 2008; 9:296-300. [PMID: 18928228 DOI: 10.3171/spi/2008/9/9/296] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECT Stabilization with rigid screw/rod fixation is the treatment of choice for craniocervical disorders requiring operative stabilization. The authors compare the relative immediate stiffness for occipital plate fixation in concordance with transarticular screw fixation (TASF), C-1 lateral mass and C-2 pars screw (C1L-C2P), and C-1 lateral mass and C-2 laminar screw (C1L-C2L) constructs, with and without a cross-link. METHODS Ten intact human cadaveric spines (Oc-C4) were prepared and mounted in a 7-axis spine simulator. Each specimen was precycled and then tested in the intact state for flexion/extension, lateral bending, and axial rotation. Motion was tracked using the OptoTRAK 3D tracking system. The specimens were then destabilized and instrumented with an occipital plate and TASF. The spine was tested with and without the addition of a cross-link. The C1L-C2P and C1L-C2L constructs were similarly tested. RESULTS All constructs demonstrated a significant increase in stiffness after instrumentation. The C1L-C2P construct was equivalent to the TASF in all moments. The C1L-C2L was significantly weaker than the C1L-C2P construct in all moments and significantly weaker than the TASF in lateral bending. The addition of a cross-link made no difference in the stiffness of any construct. CONCLUSIONS All constructs provide significant immediate stability in the destabilized occipitocervical junction. Although the C1L-C2P construct performed best overall, the TASF was similar, and either one can be recommended. Decreased stiffness of the C1L-C2L construct might affect the success of clinical fusion. This construct should be reserved for cases in which anatomy precludes the use of the other two.
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Affiliation(s)
- Michael A Finn
- Department of Neurosurgery, University of Utah, Salt Lake City, Utah 84108, USA
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Steinmetz MP, Rajpal S, Trost G. SEGMENTAL SPINAL INSTRUMENTATION IN THE MANAGEMENT OF SCOLIOSIS. Neurosurgery 2008; 63:131-8. [PMID: 18812915 DOI: 10.1227/01.neu.0000325679.25152.ee] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
ABSTRACT
SPINAL INSTRUMENTATION FOR the correction of spinal deformity began with Harrington and his rod system. The use of the Harrington rods was limited, however, because of the need for long-segment instrumentation, distraction, and the potential for hood dislodgment and construct failure. Luque subsequently introduced the next generation of spinal fixation techniques via the concept of segmental instrumentation; his use of sublaminar wires allowed the construct to be fixated to the spine at every level. This arrangement allowed greater control over correction of spinal deformities and significantly lessened the incidence of hardware dislodgment. Modern instrumentation systems, including the use of pedicle screws, permit even greater control of the spine in multiple planes during deformity correction. Newer strategies have decreased the incidence of neurological injury during implant application and provide greater stability. A review of segmental fixation, including surgical techniques, is provided in this article.
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Affiliation(s)
| | - Sharad Rajpal
- Department of Neurosurgery, University of Wisconsin, Madison, Wisconsin
| | - Gregory Trost
- Department of Neurosurgery, University of Wisconsin, Madison, Wisconsin
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Abstract
STUDY DESIGN A biomechanical testing protocol was used to study different lumbo-pelvic fixation techniques in a human cadaveric lumbar spine model. OBJECTIVE To compare the in vitro biomechanics of a novel four-rod lumbo-pelvic reconstruction technique with and with out cross-links, to that of a conventional cross-linked two-rod technique. SUMMARY OF BACKGROUND DATA Numerous lumbo-pelvic reconstruction methods based on the Galveston two-rod technique have been proposed for cases involving total sacrectomy. Recently a technique that proposes novel use of 4 supporting longitudinal rods across the lumbo-pelvic junction has been reported. No comparative in vitro biomechanical testing has been previously done to evaluate these different reconstruction methods. METHODS Five spines were evaluated in flexion, extension, left-right lateral bending and left-right axial rotation in a human total sacrectomy model. The model was comprised of cadaveric lumbar spines (L1-L5) with custom fabricated polyethylene blocks used to simulate pelvic fixation. Three conditions were evaluated: Linked Four-Rod, Linked Two-Rod, and Four-Rod (no cross-links). Flexibility and motion data were compared using a one-way repeated measures analysis of variance and SNK tests. RESULTS The Linked Four-Rod and Four-Rod conditions significantly decreased flexibility and reduced L5-Pelvic motion over the Linked Two-Rod construct in flexion and extension. The Linked Four-Rod condition significantly decreased flexibility in left-right axial rotation compared with the Four-Rod and Linked Two-Rod conditions. No significant differences occurred in relative lateral movement between left and right pelvic polyethylene blocks. CONCLUSION The four-rod technique improved fixation stability over the conventional linked two-rod technique in flexion and extension, and when cross-linked, in left-right axial rotation. The four-rod technique also significantly reduced L5-Pelvic junction movement in flexionand extension, which may have implications for bony fusion. The use of cross-links is recommended.
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