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Calek AK, Cornaz F, Suter M, Fasser MR, Farshad M, Widmer J. Endplate weakening during cage bed preparation significantly reduces endplate load capacity. 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 2024; 33:2621-2629. [PMID: 38733400 DOI: 10.1007/s00586-024-08289-4] [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: 11/09/2023] [Revised: 04/17/2024] [Accepted: 04/19/2024] [Indexed: 05/13/2024]
Abstract
PURPOSE To analyze the effect of endplate weakness prior to PLIF or TLIF cage implantation and compare it to the opposite intact endplate of the same vertebral body. In addition, the influence of bone quality on endplate resistance was investigated. METHODS Twenty-two human lumbar vertebrae were tested in a ramp-to-failure test. One endplate of each vertebral body was tested intact and the other after weakening with a rasp (over an area of 200 mm2). Either a TLIF or PLIF cage was then placed and the compression load was applied across the cage until failure of the endplate. Failure was defined as the first local maximum of the force measurement. Bone quality was assessed by determining the Hounsfield units (HU) on CT images. RESULTS With an intact endplate and a TLIF cage, the median force to failure was 1276.3N (693.1-1980.6N). Endplate weakening reduced axial endplate resistance to failure by 15% (0-23%). With an intact endplate and a PLIF cage, the median force to failure was 1057.2N (701.2-1735.5N). Endplate weakening reduced axial endplate resistance to failure by 36.6% (7-47.9%). Bone quality correlated linearly with the force at which endplate failure occurred. Intact and weakened endplates showed a strong positive correlation: intact-TLIF: r = 0.964, slope of the regression line (slope) = 11.8, p < 0.001; intact-PLIF: r = 0.909, slope = 11.2, p = 5.5E-05; weakened-TLIF: r = 0.973, slope = 12.5, p < 0.001; weakened-PLIF: r = 0.836, slope = 6, p = 0.003. CONCLUSION Weakening of the endplate during cage bed preparation significantly reduces the resistance of the endplate to subsidence to failure: endplate load capacity is reduced by 15% with TLIF and 37% with PLIF. Bone quality correlates with the force at which endplate failure occurs.
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Affiliation(s)
- Anna-Katharina Calek
- Department of Orthopedics, Balgrist University Hospital, University of Zurich, Forchstrasse 340, 8008, Zurich, Switzerland.
| | - Frédéric Cornaz
- Department of Orthopedics, Balgrist University Hospital, University of Zurich, Forchstrasse 340, 8008, Zurich, Switzerland
| | - Mauro Suter
- Spine Biomechanics, Department of Orthopedic Surgery, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
| | - Marie-Rosa Fasser
- Spine Biomechanics, Department of Orthopedic Surgery, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
| | - Mazda Farshad
- Department of Orthopedics, Balgrist University Hospital, University of Zurich, Forchstrasse 340, 8008, Zurich, Switzerland
- University Spine Center Zurich, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
| | - Jonas Widmer
- Spine Biomechanics, Department of Orthopedic Surgery, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
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Calek AK, Cornaz F, Suter M, Fasser MR, Baumgartner S, Sager P, Farshad M, Widmer J. Load distribution on intervertebral cages with and without posterior instrumentation. Spine J 2024; 24:889-898. [PMID: 37924848 DOI: 10.1016/j.spinee.2023.10.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Revised: 09/18/2023] [Accepted: 10/28/2023] [Indexed: 11/06/2023]
Abstract
BACKGROUND CONTEXT Posterior and transforaminal lumbar interbody fusion (PLIF, TLIF) are well-established procedures for spinal fusion. However, little is known about load sharing between cage, dorsal construct, and biological tissue within the instrumented lumbar spine. PURPOSE The aim of this study was to quantify the forces acting on cages under axial compression force with and without posterior instrumentation. STUDY DESIGN Biomechanical cadaveric study. METHODS Ten lumbar spinal segments were tested under uniaxial compression using load cell instrumented intervertebral cages. The force was increased in 100N increments to 1000N or a force greater than 500N on one load cell. Each specimen was tested after unilateral PLIF (uPLIF), bilateral PLIF (bPLIF) and TLIF each with/without posterior instrumentation. Dorsal instrumentation was performed with 55N of compression per side. RESULTS Cage insertion resulted in median cage preloads of 16N, 29N and 35N for uPLIF, bPLIF, and TLIF. The addition of compressed dorsal instrumentation increased the median preload to 224N, 328N, and 317N, respectively. With posterior instrumentation, the percentage of the external load acting on the intervertebral cage was less than 25% at 100N (uPLIF: 14.2%; bPLIF: 16%; TLIF: 11%), less than 45% at 500N (uPLIF: 31.8%; bPLIF: 41.1%; TLIF: 37.9%) and less than 50% at 1000N (uPLIF: 40.3%; bPLIF: 49.7%; TLIF: 43.4%). Without posterior instrumentation, the percentage of external load on the cages was significantly higher with values above 50% at 100N (uPLIF: 55.6%; bPLIF: 75.5%; TLIF: 66.8%), 500N (uPLIF: 71.7%; bPLIF: 79.2%; TLIF: 65.4%), and 1000N external load (uPLIF: 73%; bPLIF: 80.5%; TLIF: 66.1%). For absolute loads, preloads and external loads must be added together. CONCLUSIONS Without posterior instrumentation, the intervertebral cages absorb more than 50% of the axial load and the load distribution is largely independent of the loading amplitude. With posterior instrumentation, the external load acting on the cages is significantly lower and the load distribution becomes load amplitude dependent, with a higher proportion of the load transferred by the cages at high loads. The bPLIF cages tend to absorb more force than the other two cage configurations. CLINICAL SIGNIFICANCE Cage instrumentation allows some of the compression force to be transmitted through the cage to the screws below, better distributing and reducing the overall force on the pedicle screws at the end of the construct and on the rods.
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Affiliation(s)
- Anna-Katharina Calek
- Department of Orthopedics, Balgrist University Hospital, University of Zurich, Forchstrasse 340, Zurich CH-8008, Switzerland.
| | - Frédéric Cornaz
- Department of Orthopedics, Balgrist University Hospital, University of Zurich, Forchstrasse 340, Zurich CH-8008, Switzerland
| | - Mauro Suter
- Spine Biomechanics, Department of Orthopedic Surgery, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
| | - Marie-Rosa Fasser
- Spine Biomechanics, Department of Orthopedic Surgery, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
| | - Sina Baumgartner
- Spine Biomechanics, Department of Orthopedic Surgery, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
| | - Philipp Sager
- Spine Biomechanics, Department of Orthopedic Surgery, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
| | - Mazda Farshad
- Department of Orthopedics, Balgrist University Hospital, University of Zurich, Forchstrasse 340, Zurich CH-8008, Switzerland; University Spine Center Zurich, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
| | - Jonas Widmer
- Spine Biomechanics, Department of Orthopedic Surgery, Balgrist University Hospital, University of Zurich, Zurich, Switzerland.
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Han L, Ma H, Li Q, Yuan J, Yang H, Qin Y, Lu X. The association of rod curvature with postoperative outcomes in patients undergoing posterior lumbar interbody fusion for spinal stenosis: a retrospective case-control study. BMC Musculoskelet Disord 2023; 24:304. [PMID: 37072780 PMCID: PMC10111816 DOI: 10.1186/s12891-023-06404-y] [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: 11/10/2022] [Accepted: 04/06/2023] [Indexed: 04/20/2023] Open
Abstract
BACKGROUND Restoration of sagittal balance is a crucial consideration in posterior lumbar interbody fusion (PLIF) surgery and adverse postoperative outcomes are associated with inadequate restoration of sagittal alignment. However, there remains a shortage of substantial evidence regarding the effect of rod curvature on both sagittal spinopelvic radiographic parameters and clinical outcomes. METHOD A retrospective case-control study was conducted in this study. Patient demographics (age, gender, height, weight and BMI), surgical characteristics (number of fused levels, surgical time, blood loss and hospital stay) and radiographic parameters (lumbar lordosis [LL], sacral slope [SS], pelvic incidence [PI], pelvic tilt [PT], PI-LL, Cobb angle of fused segments [Cobb], rod curvature [RC], Posterior tangent angle of fused segments [PTA] and RC-PTA) were analyzed. RESULTS Patients in the abnormal group had older mean age and suffered more blood loss than those in the normal group. In addition, RC and RC-PTA were significantly lower in the abnormal group compared to the normal group. Multivariate regression analysis revealed that lower age (OR = 0.94; 95% CI: 0.89-0.99; P = 0.0187), lower PTA (OR = 0.91; 95% CI: 0.85-0.96; P = 0.0015) and higher RC (OR = 1.35; 95% CI: 1.20-1.51; P < 0.0001) were related to higher odds of better surgical outcomes. The receiver operating characteristic curve analysis showed that the ROC curve (AUC) for predicting outcomes of surgery by RC classifier was 0.851 (0.769-0.932). CONCLUSIONS In patients who underwent PLIF surgery for lumbar spinal stenosis, those who had a satisfactory postoperative outcome tended to be younger, had lower blood loss, and higher values of RC and RC-PTA compared to those who had poor recovery and required revision surgery. Additionally, RC was found to be a reliable predictor of postoperative outcomes.
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Affiliation(s)
- Lin Han
- Department of Orthopaedics, Third Affiliated Hospital of Naval Medical University, Shanghai, 200433, China
- Department of Orthopaedics, Shanghai Changzheng Hospital, Second Military Medical University, Shanghai, 200003, China
| | - Hongdao Ma
- Department of Orthopaedics, Shanghai Changzheng Hospital, Second Military Medical University, Shanghai, 200003, China
| | - Qisheng Li
- Department of Orthopaedics, Shanghai Changzheng Hospital, Second Military Medical University, Shanghai, 200003, China
| | - Jincan Yuan
- Department of Orthopaedics, Shanghai Changzheng Hospital, Second Military Medical University, Shanghai, 200003, China
| | - Haisong Yang
- Department of Orthopaedics, Shanghai Changzheng Hospital, Second Military Medical University, Shanghai, 200003, China
| | - Yuchen Qin
- Department of Health Statistics, Second Military Medical University, Shanghai, 200003, China.
| | - Xuhua Lu
- Department of Orthopaedics, Shanghai Changzheng Hospital, Second Military Medical University, Shanghai, 200003, China.
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Zhao Y, Yuan S, Tian Y, Liu X. Risk Factors Related to Superior Facet Joint Violation During Lumbar Percutaneous Pedicle Screw Placement in Minimally Invasive Transforaminal Lumbar Interbody Fusion (MIS-TLIF). World Neurosurg 2020; 139:e716-e723. [PMID: 32360675 DOI: 10.1016/j.wneu.2020.04.118] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 04/13/2020] [Accepted: 04/15/2020] [Indexed: 11/28/2022]
Abstract
OBJECTIVE To investigate the incidence of superior facet joint violation (FJV) during percutaneous pedicle screw placement in minimally invasive transforaminal lumbar interbody fusion, and assess the possible risk factors for FJV. METHODS An analysis of 91 patients with lumbar degenerative diseases treated with percutaneous pedicle screw placement via minimally invasive transforaminal lumbar interbody fusion from 2012 to 2018 was performed. Superior FJV was evaluated and graded by 3-dimensional lumbar computed tomography reconstruction. Analysis of possible risk factors included general condition of patients, anatomical characteristics of facet joint (FJ; axial, sagittal, and coronal diameters of FJ, facet angle, lumbar lordosis angle, lumbar lordosis index, and depth of lamina), and surgical factors (pedicle screw angle, screw-superior FJ distance, cranial angle, proximal rod length, and rod contouring). RESULTS The overall violation rate of superior FJ was 34.07% (62/182), and high-grade violation rate was 16.06% (27/182). The logistic regression analysis revealed that body mass index ≥30 kg/m2 and pedicle screw placement at L5 were independent risk factors of FJV. Anatomical factors showed that the incidence of FJV was significantly increased when axial, sagittal, and coronal diameters of FJ were all ≥12 mm or FA was ≥40°. Surgical factors showed that the FJV group had a smaller pedicle screw angle and screw-superior FJ distance compared with the non-FJV group (P < 0.05). CONCLUSIONS Body mass index ≥30 kg/m2 and pedicle screw placement at L5 were independent risk factors of superior FJV. FJV was more likely to occur in hypertrophic FJ (axial, sagittal, and coronal diameters ≥12 mm) or coronal orientation (FA ≥40°).
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Affiliation(s)
- Yiwei Zhao
- Department of Orthopedics, Qilu Hospital of Shandong University, Jinan, Shandong Province, P. R. China; Cheeloo College of Medicine, Shandong University, Jinan, Shandong Province, P. R. China
| | - Suomao Yuan
- Department of Orthopedics, Qilu Hospital of Shandong University, Jinan, Shandong Province, P. R. China
| | - Yonghao Tian
- Department of Orthopedics, Qilu Hospital of Shandong University, Jinan, Shandong Province, P. R. China
| | - Xinyu Liu
- Department of Orthopedics, Qilu Hospital of Shandong University, Jinan, Shandong Province, P. R. China.
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