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Ruf M, Pitzen T, Nennstiel I, Volkheimer D, Drumm J, Püschel K, Wilke HJ. The effect of posterior compression of the facet joints for initial stability and sagittal profile in the treatment of thoracolumbar fractures: a biomechanical study. 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 2021; 31:28-36. [PMID: 34773149 DOI: 10.1007/s00586-021-07034-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 08/01/2021] [Accepted: 10/11/2021] [Indexed: 11/29/2022]
Abstract
PURPOSE Surgical treatment of thoracolumbar A3-fractures usually comprises posterior fixation-in neutral position or distraction-potentially followed by subsequent anterior support. We hypothesized that additional posterior compression in circumferential stabilization may increase stability by locking the facets, and better restore the sagittal profile. METHODS Burst fractures Type A3 were created in six fresh frozen cadaver spine segments (T12-L2). Testing was performed in a custom-made spinal loading simulator. Loads were applied as pure bending moments of ± 3.75 Nm in all six movement axes. We checked range of motion, neutral zone and Cobb's angle over the injured/treated segment within the following conditions: Intact, fractured, instrumented in neutral alignment, instrumented in distraction, with cage left in posterior distraction, with cage with posterior compression. RESULTS We found that both types of instrumentation with cage stabilized the segment compared to the fractured state in all motion planes. For flexion/extension and lateral bending, flexibility was decreased even compared to the intact state, however, not in axial rotation, being the most critical movement axis. Additional posterior compression in the presence of a cage significantly decreased flexibility in axial rotation, thus achieving stability comparable to the intact state even in this movement axis. In addition, posterior compression with cage significantly increased lordosis compared to the distracted state. CONCLUSION Among different surgical modifications tested, circumferential fixation with final posterior compression as the last step resulted in superior stability and improved sagittal alignment. Thus, posterior compression as the last step is recommended in these pathologies.
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Affiliation(s)
- Michael Ruf
- Center for Spine Surgery, Orthopedics, and Traumatology, SRH Klinikum Karlsbad-Langensteinbach, Guttmannstrasse 1, 76307, Karlsbad, Germany
| | - Tobias Pitzen
- Center for Spine Surgery, Orthopedics, and Traumatology, SRH Klinikum Karlsbad-Langensteinbach, Guttmannstrasse 1, 76307, Karlsbad, Germany
| | - Ivo Nennstiel
- Center for Orthopedic Surgery and Traumatology, SRH Central Hospital Suhl, Albert-Schweitzer-Strasse 2, 98527, Suhl, Germany
| | - David Volkheimer
- Institute of Orthopaedic Research and Biomechanics, University of Ulm, Helmholtzstrasse 14, 89901, Ulm, Germany
| | - Jörg Drumm
- Center for Spine Surgery, Orthopedics, and Traumatology, SRH Klinikum Karlsbad-Langensteinbach, Guttmannstrasse 1, 76307, Karlsbad, Germany
| | - Klaus Püschel
- Department of Legal Medicine, University Hospital Hamburg-Eppendorf, Butenfeld 34, 22529, Hamburg, Germany
| | - Hans-Joachim Wilke
- Institute of Orthopaedic Research and Biomechanics, University of Ulm, Helmholtzstrasse 14, 89901, Ulm, Germany.
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Wong CE, Hu HT, Tsai CH, Li JL, Hsieh CC, Huang KY. Comparison of Posterior Fixation Strategies for Thoracolumbar Burst Fracture: A Finite Element Study. J Biomech Eng 2021; 143:071007. [PMID: 33729440 DOI: 10.1115/1.4050537] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Indexed: 11/08/2022]
Abstract
The management of thoracolumbar (TL) burst fractures remained challenging. Due to the complex nature of the fractured vertebrae and the lack of clinical and biomechanical evidence, currently, there was still no guideline to select the optimal posterior fixation strategy for TL burst fracture. We utilized a T10-L3 TL finite element model to simulate L1 burst fracture and four surgical constructs with one- or two-level suprajacent and infrajacent instrumentation (U1L1, U1L2, U2L1, and U2L2). This study was aimed to compare the biomechanical properties and find an optimal fixation strategy for TL burst fracture in order to minimize motion in the fractured level without exerting significant burden in the construct. Our result showed that two-level infrajacent fixation (U1L2 and U2L2) resulted in greater global motion reduction ranging from 66.0 to 87.3% compared to 32.0 to 47.3% in one-level infrajacent fixation (U1L1 and U2L1). Flexion produced the largest pathological motion in the fractured level but the differences between the constructs were small, all within 0.26 deg. Comparisons in implant stress showed that U2L1 and U2L2 had an average 25.3 and 24.8% less von Mises stress in the pedicle screws compared to U1L1 and U1L2, respectively. The construct of U2L1 had better preservation of the physiological spinal motion while providing sufficient range of motion reduction at the fractured level. We suggested that U2L1 is a good alternative to the standard long-segment fixation with better preservation of physiological motion and without an increased risk of implant failure.
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Affiliation(s)
- Chia-En Wong
- Section of Neurosurgery, Department of Surgery, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan 704, Taiwan
| | - Hsuan-Teh Hu
- Department of Civil Engineering, National Cheng Kung University, Tainan 701, Taiwan; Department of Civil and Disaster Prevention Engineering, National United University, Miaoli 360, Taiwan
| | - Cho-Hsuan Tsai
- Department of Civil Engineering, National Cheng Kung University, Tainan 701, Taiwan
| | - Jun-Liang Li
- Department of Otolaryngology, Tungs' Taichung MetroHarbor Hospital, Taichung 433, Taiwan
| | - Chin-Chiang Hsieh
- Department of Radiology, Tainan Hospital, Ministry of Health and Welfare, Tainan 700, Taiwan
| | - Kuo-Yuan Huang
- Department of Orthopedics,National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan
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Lindtner RA, Mueller M, Schmid R, Spicher A, Zegg M, Kammerlander C, Krappinger D. Monosegmental anterior column reconstruction using an expandable vertebral body replacement device in combined posterior-anterior stabilization of thoracolumbar burst fractures. Arch Orthop Trauma Surg 2018; 138:939-951. [PMID: 29623406 PMCID: PMC5999121 DOI: 10.1007/s00402-018-2926-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Indexed: 12/26/2022]
Abstract
INTRODUCTION In combined posterior-anterior stabilization of thoracolumbar burst fractures, the expandable vertebral body replacement device (VBRD) is typically placed bisegmentally for anterior column reconstruction (ACR). The aim of this study, however, was to assess feasibility, outcome and potential pitfalls of monosegmental ACR using a VBRD. In addition, clinical and radiological outcome of monosegmental ACR was related to that of bisegmental ACR using the same thoracoscopic technique. METHODS Thirty-seven consecutive neurologically intact patients with burst fractures of the thoracolumbar junction (T11-L2) treated by combined posterior-anterior stabilization were included. Monosegmental ACR was performed in 18 and bisegmental ACR in 19 patients. Fracture type and extent of vertebral body comminution were determined on preoperative CT scans. Monosegmental and bisegmental kyphosis angles were analyzed preoperatively, postoperatively and at final radiological follow-up. Clinical outcome was assessed after a minimum of 2 years (74 ± 45 months; range 24-154; follow-up rate 89.2%) using VAS Spine Score, RMDQ, ODI and WHOQOL-BREF. RESULTS Monosegmental ACR resulted in a mean monosegmental and bisegmental surgical correction of - 15.6 ± 7.7° and - 14.7 ± 8.1°, respectively. Postoperative monosegmental and bisegmental loss of correction averaged 2.7 ± 2.7° and 5.2 ± 3.7°, respectively. Two surgical pitfalls of monosegmental ACR were identified: VBRD positioning (1) onto the weak cancellous bone (too far cranially to the inferior endplate of the fractured vertebra) and (2) onto a significantly compromised inferior endplate with at least two (even subtle) fracture lines. Ignoring these pitfalls resulted in VBRD subsidence in five cases. When relating the clinical and radiological outcome of monosegmental ACR to that of bisegmental ACR, no significant differences were found, except for frequency of VBRD subsidence (5 vs. 0, P = 0.02) and bisegmental loss of correction (5.2 ± 3.7° vs. 2.6 ± 2.5°, P = 0.022). After exclusion of cases with VBRD subsidence, the latter did not reach significance anymore (4.9 ± 4.0° vs. 2.6 ± 2.5°, P = 0.084). CONCLUSIONS This study indicates that monosegmental ACR using a VBRD is feasible in thoracolumbar burst fractures if the inferior endplate is intact (incomplete burst fractures) or features only a single simple split fracture line (burst-split fractures). If the two identified pitfalls are avoided, monosegmental ACR may be a viable alternative to bisegmental ACR in selected thoracolumbar burst fractures to spare a motion segment and to reduce the distance for bony fusion.
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Affiliation(s)
- Richard A Lindtner
- Department of Trauma Surgery, Medical University of Innsbruck, Anichstraße 35, 6020, Innsbruck, Austria
| | - Max Mueller
- Department of Trauma Surgery, Medical University of Innsbruck, Anichstraße 35, 6020, Innsbruck, Austria
| | - Rene Schmid
- Department of Trauma Surgery, Medical University of Innsbruck, Anichstraße 35, 6020, Innsbruck, Austria
| | - Anna Spicher
- Department of Trauma Surgery, Medical University of Innsbruck, Anichstraße 35, 6020, Innsbruck, Austria
| | - Michael Zegg
- Department of Trauma Surgery, Medical University of Innsbruck, Anichstraße 35, 6020, Innsbruck, Austria
| | - Christian Kammerlander
- Department of Trauma Surgery, Medical University of Innsbruck, Anichstraße 35, 6020, Innsbruck, Austria
- Department of General, Trauma and Reconstructive Surgery, Ludwig Maximilian University Munich, Marchioninistrasse 15, 81377, Munich, Germany
| | - Dietmar Krappinger
- Department of Trauma Surgery, Medical University of Innsbruck, Anichstraße 35, 6020, Innsbruck, Austria.
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Mundis GM, Eastlack RK, Moazzaz P, Turner AWL, Cornwall GB. Contribution of Round vs. Rectangular Expandable Cage Endcaps to Spinal Stability in a Cadaveric Corpectomy Model. Int J Spine Surg 2015; 9:53. [PMID: 26609508 DOI: 10.14444/2053] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND Expandable cages are gaining popularity in anterior reconstruction of the thoracolumbar spine following corpectomy as they can provide adjustable distraction and deformity correction. Rectangular, rather than circular, endcaps provide increased resistance to subsidence by spanning the apophyseal ring; however their impact on construct stability is not known. The objective of this study was to investigate the contribution of expandable corpectomy cage endcap shape (round vs. rectangular) and fixation method (anterior plate vs. posterior pedicle screws) to the stability of an L1 sub-total corpectomy construct. METHODS Eight fresh-frozen cadaveric specimens (T11-L3) were subjected to multi-directional flexibility testing to 6 N·m with a custom spine simulator. Test conditions were: intact, L1 sub-total corpectomy defect, expandable cage (round endcap) alone, expandable cage (round endcap) with anterior plate, expandable cage (round endcap) with bilateral pedicle screws, expandable cage (rectangular endcap) alone, expandable cage (rectangular endcap) with anterior plate, expandable cage (rectangular endcap) with bilateral pedicle screws. Range-of-motion across T12-L2 was measured with an optoelectronic system. RESULTS The expandable cage alone with either endcap provided significant stability to the corpectomy defect, reducing motion to intact levels in flexion-extension with both endcap types, and in lateral bending with rectangular endcaps. Round endcaps allowed greater motion than intact in lateral bending, and axial rotation ROM was greater than intact for both endcaps. Supplemental fixation provided the most rigid constructs, although there were no significant differences between instrumentation or endcap types. CONCLUSIONS These results suggest anterior-only fixation may be adequate when using an expandable cage in a sub-total corpectomy application and choice of endcap type may be driven by other factors such as subsidence resistance.
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Affiliation(s)
- Gregory M Mundis
- Scripps Clinic Division of Orthopedic Surgery, San Diego, CA ; San Diego Spine Foundation, San Diego, CA
| | - Robert K Eastlack
- Scripps Clinic Division of Orthopedic Surgery, San Diego, CA ; San Diego Spine Foundation, San Diego, CA
| | - Payam Moazzaz
- Orthopaedic Specialists of North County, Tri-City Medical Center Orthopaedic and Spine Institute, Oceanside, CA
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Panchal RR, Matheis EA, Gudipally M, Hussain MM, Kim KD, Bucklen BS. Is lateral stabilization enough in thoracolumbar burst fracture reconstruction? A biomechanical investigation. Spine J 2015; 15:2247-53. [PMID: 26008679 DOI: 10.1016/j.spinee.2015.05.020] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Revised: 05/01/2015] [Accepted: 05/19/2015] [Indexed: 02/03/2023]
Abstract
BACKGROUND CONTEXT Traditional reconstruction for burst fractures involves columnar support with posterior fixation at one or two levels cephalad/caudad; however, some surgeons choose to only stabilize the vertebral column. PURPOSE The aim was to distinguish biomechanical differences in stability between a burst fracture stabilized through a lateral approach using corpectomy spacers of different end plate sizes with and without integrated screws and with and without posterior fixation. STUDY DESIGN/SETTING This was an in vitro biomechanical study assessing thoracolumbar burst fracture stabilization. METHODS Six human spines (T11-L3) were tested on a six-degrees-of-freedom simulator enabling unconstrained range of motion (ROM) at ±6 N·m in flexion-extension (FE), lateral bending (LB), and axial rotation (AR) after a simulated burst fracture at L1. Expandable corpectomy spacers with/without integrated screws (Fi/F; FORTIFY Integrated/FORTIFY; Globus Medical, Inc., Audubon, PA, USA) were tested with different end plate sizes (21×23 mm, 22×40-50 mm). Posterior instrumentation (PI) via bilateral pedicle screws and rods was used one level above and one level below the burst fracture. Lateral plate (LP) fixation was tested. Devices were tested in the following order: intact; Fi21×23; Fi21×23+PI; F21×23+PI+LP; F21×23+LP; F22×40-50+LP; F22×40-50+PI+LP; Fi22×40-50+PI; Fi22×40-50. RESULTS In FE and AR, constructs without PI showed no significant difference (p<.05) in stability compared with intact. In LB, F22×40-50+LP showed a significant increase in stability relative to intact, but no other construct without PI reached significance. In FE and LB, circumferential constructs were significantly more stable than intact. In AR, no construct showed significant differences in motion when compared with the intact condition. CONCLUSIONS Constructs without posterior fixation were the least stable of all tested constructs. Circumferential fixation provided greater stability in FE and LB than lateral fixation and intact. Axial rotation showed no significant differences in any construct compared with the intact state.
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Affiliation(s)
- Ripul R Panchal
- Department of Neurological Surgery, University of California, Davis, 4860 Y St, Ste. 3740, Sacramento, CA 95817, USA
| | - Erika A Matheis
- Muskuloskeletal Education and Research Center, A Division of Globus Medical Inc., 2560 General Armistead Ave., Audubon, PA 19403, USA.
| | - Manasa Gudipally
- Muskuloskeletal Education and Research Center, A Division of Globus Medical Inc., 2560 General Armistead Ave., Audubon, PA 19403, USA
| | - Mir M Hussain
- Muskuloskeletal Education and Research Center, A Division of Globus Medical Inc., 2560 General Armistead Ave., Audubon, PA 19403, USA
| | - Kee D Kim
- Department of Neurological Surgery, University of California, Davis, 4860 Y St, Ste. 3740, Sacramento, CA 95817, USA
| | - Brandon S Bucklen
- Muskuloskeletal Education and Research Center, A Division of Globus Medical Inc., 2560 General Armistead Ave., Audubon, PA 19403, USA
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Kim JH, Rhee JM, Enyo Y, Hutton WC, Kim SS. A biomechanical comparison of 360° stabilizations for corpectomy and total spondylectomy: a cadaveric study in the thoracolumbar spine. J Orthop Surg Res 2015; 10:99. [PMID: 26126620 PMCID: PMC4490731 DOI: 10.1186/s13018-015-0240-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2015] [Accepted: 06/15/2015] [Indexed: 11/22/2022] Open
Abstract
Background To date, there has been no adequate biomechanical model that would allow a quantitative comparison in terms of stability/stiffness between a corpectomy with the posterior column preserved and a total spondylectomy with the posterior column sacrificed. The objective of this study was to perform a biomechanical comparison of 360° stabilizations for corpectomy and total spondylectomy, using the human thoracolumbar spine. Methods Five human cadaveric thoracolumbar spines (T8-L2) were tested according to the following loading protocol: axial compression, flexion, extension, lateral bending to the right and left, and axial rotation to the right and left. This loading protocol was applied three times. Each specimen was tested intact, after corpectomy, and after total spondylectomy. The relative stiffness of each motion segment was determined for each test. Results There was no significant difference in stiffness after reconstruction of total spondylectomy versus corpectomy in our thoracolumbar model. Our construct consisted of an anterior cage and four-level pedicle screw instrumentation (two above and two below) and provided similar stiffness in both models. Despite the additional bone resection in a total spondylectomy versus corpectomy, the constructs did not differ biomechanically. Additionally, there was no significant difference in stiffness between the intact specimen and either reconstruction model. Conclusions A classic corpectomy, which leaves the posterior column intact, is no better in terms of stability/stiffness than a total spondylectomy carried out using a shorter cage, followed by compression using posterior instrumentation.
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Affiliation(s)
- Jung-Hoon Kim
- Department of Orthopaedic Surgery, Ilsan Paik Hospital, Inje University, Goyang-si, Korea.
| | - John M Rhee
- Department of Orthopaedic Surgery, Emory Spine Center, Emory University, Atlanta, GA, USA.
| | - Yoshio Enyo
- Veterans Affairs Medical Center, Atlanta, GA, USA.
| | - William C Hutton
- Department of Orthopaedic Surgery, Emory Spine Center, Emory University, Atlanta, GA, USA.
| | - Sung-Soo Kim
- Department of Orthopaedic Surgery, Haeundae Paik Hospital, Inje University, Busan, Korea.
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Range of motion after thoracolumbar corpectomy: evaluation of analogous constructs with a novel low-profile anterior dual-rod system and a traditional dual-rod system. 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 2015; 26:666-670. [PMID: 25917825 DOI: 10.1007/s00586-015-3966-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Revised: 04/14/2015] [Accepted: 04/14/2015] [Indexed: 10/23/2022]
Abstract
STUDY DESIGN An in vitro biomechanical study. OBJECTIVES To compare the biomechanical stability of traditional and low-profile thorocolumbar anterior instrumentation after a corpectomy with cross-connectors. Dual-rod anterior thoracolumbar lateral plates (ATLP) have been used clinically to stabilize the thorocolumbar spine. METHODS The stability of a low-profile dual-rod system (LP DRS) and a traditional dual-rod system (DRS) was compared using a calf spine model. Two groups of seven specimens were tested intact and then in the following order: (1) ATLP with two cross-connectors and spacer; (2) ATLP with one cross-connector and spacer; (3) ATLP with spacer. Data were normalized to intact (100 %) and statistical analysis was used to determine between-group significances. RESULTS Both constructs reduced motion compared to intact in flexion-extension and lateral bending. Axial rotation motion became unstable after the corpectomy and motion was greater than intact, even with two cross-connectors with both systems. Relative to their respective intact groups, LP DRS significantly reduced motion compared to analogous DRS in flexion-extension. The addition of cross-connectors reduced motion in all loading modes. CONCLUSIONS The LP DRS provides 7.5 mm of reduced height with similar biomechanical performance. The reduced height may be beneficiary by reduced irritation and impingement on adjacent structures.
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Yilmaz M, Karakasli A, Kalemci O, Kizmazoglu C, Yuksel ZK, Arda NM, Yucesoy K. Asymmetric Posterior Thoracolumbar Fixation following a Posterolateral Transpedicular Approach for Unilateral Vertebral Disease. Neurol Med Chir (Tokyo) 2015; 55:564-9. [PMID: 25797773 PMCID: PMC4628189 DOI: 10.2176/nmc.oa.2014-0085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The present study aimed to evaluate the clinical outcomes of patients who underwent asymmetrical posterior screw fixation for the treatment of unilateral posterior vertebral pathological entities. The study included 21 patients with a spinal tumor who underwent asymmetrical posterior spinal fusion surgery between April 2009 and March 2012. The American Spinal Injury Association (ASIA) motor score visual analog scale (VAS) score were used as the outcome measure at admission and follow-up. Among the 21 patients, 12 were male and 9 were female, and mean age was 50.71 (range, 24–78) years. Mean follow-up was 16.04 (range, 4–47) months. Postoperatively, neurological findings did not deteriorate in any of the patients. Among the ASIA grade C and D patients, eight (38%) of them exhibited clinical stability or recovery to ASIA E, whereas none of the ASIA B patients scores changed postoperatively. Perioperative complications were noted in six patients (28%). Spinal stability and fusion were achieved in 18 (85%) patients. The surgical asymmetrical fixation technique described reduced the duration of surgery, and the patients required less dissection of paraspinal muscles than bilateral symmetrical fixation. Asymmetrical fixation provides good stabilization for unilateral thoracolumbar vertebral pathological entities, and facilitates rapid rehabilitation of such patients, who are often elderly with comorbidities.
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Affiliation(s)
- Murat Yilmaz
- Department of Neurosurgery, Dokuz Eylül University
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Calvert GC, Lawrence BD, Abtahi AM, Bachus KN, Brodke DS. Cortical screws used to rescue failed lumbar pedicle screw construct: a biomechanical analysis. J Neurosurg Spine 2014; 22:166-72. [PMID: 25478820 DOI: 10.3171/2014.10.spine14371] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
OBJECT Cortical trajectory screw constructs, developed as an alternative to pedicle screw fixation for the lumbar spine, have similar in vitro biomechanics. The possibility of one screw path having the ability to rescue the other in a revision scenario holds promise but has not been evaluated. The objective in this study was to investigate the biomechanical properties of traditional pedicle screws and cortical trajectory screws when each was used to rescue the other in the setting of revision. METHODS Ten fresh-frozen human lumbar spines were instrumented at L3-4, 5 with cortical trajectory screws and 5 with pedicle screws. Construct stiffness was recorded in flexion/extension, lateral bending, and axial rotation. The L-3 screw pullout strength was tested to failure for each specimen and salvaged with screws of the opposite trajectory. Mechanical stiffness was again recorded. The hybrid rescue trajectory screws at L-3 were then tested to failure. RESULTS Cortical screws, when used in a rescue construct, provided stiffness in flexion/extension and axial rotation similar to that provided by the initial pedicle screw construct prior to failure. The rescue pedicle screws provided stiffness similar to that provided by the primary cortical screw construct in flexion/extension, lateral bending, and axial rotation. In pullout testing, cortical rescue screws retained 60% of the original pedicle screw pullout strength, whereas pedicle rescue screws retained 65% of the original cortical screw pullout strength. CONCLUSIONS Cortical trajectory screws, previously studied as a primary mode of fixation, may also be used as a rescue option in the setting of a failed or compromised pedicle screw construct in the lumbar spine. Likewise, a standard pedicle screw construct may rescue a compromised cortical screw track. Cortical and pedicle screws each retain adequate construct stiffness and pullout strength when used for revision at the same level.
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Affiliation(s)
- Graham C Calvert
- Department of Orthopaedics, Orthopaedic Bioengineering Laboratory, University of Utah, Salt Lake City, Utah
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Pneumaticos SG, Triantafyllopoulos GK, Giannoudis PV. Advances made in the treatment of thoracolumbar fractures: current trends and future directions. Injury 2013; 44:703-12. [PMID: 23287553 DOI: 10.1016/j.injury.2012.12.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 12/03/2012] [Indexed: 02/02/2023]
Abstract
Thoracolumbar fractures are common injuries after blunt trauma and are accompanied with significant morbidity, including neurologic deficit. Parallel to the evolution of initial management during the past few years, efforts have been concentrated on determining clear indications for surgical treatment, as there is no agreement over superiority of conservative or operative treatment. Various classification systems have been used for identifying those injuries requiring surgical intervention. Moreover, novel trends in surgical techniques, including minimal invasive surgery, implants and rehabilitation protocols have provided new, promising aspects regarding the treatment and outcomes of thoracolumbar fractures. The present review focuses on these recent advances.
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Affiliation(s)
- Spyros G Pneumaticos
- Academic Department of Trauma and Orthopaedics, School of Medicine, University of Athens, Greece.
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