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Adetokunbo A Oyelese - One of the best experts on this subject based on the ideXlab platform.
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minimally invasive thoracolumbar Corpectomy and stabilization for unstable burst fractures using intraoperative computed tomography and computer assisted spinal navigation
World Neurosurgery, 2019Co-Authors: James Y H Yu, Ziya L Gokaslan, Jared Fridley, Albert E Telfeian, Adetokunbo A OyeleseAbstract:Background Minimally invasive surgery using a mini-open lateral retropleural or retroperitoneal approach for Corpectomy is a well-described procedure for treating unstable thoracolumbar burst fractures. Most surgeons have incorporated fluoroscopy for localization and determination of hardware placement accuracy; however, the utility of computer-assisted image-guided spinal navigation has not been well described. We report a series of mini-open lateral approach thoracolumbar Corpectomy cases using either fluoroscopy or intraoperative computed tomography (iCT) with computer-assisted navigation and discuss the technical nuances and advantages of using iCT with navigation versus fluoroscopy. Methods A retrospective review and analysis was performed of the cases of 20 patients with thoracolumbar burst fractures surgically managed via mini-open lateral Corpectomy with fluoroscopy (2013–2015) or iCT navigation (2015–2017). The surgical outcomes were evaluated by the estimated blood loss, operative time, hospital stay, and need for revision. The clinical outcomes were evaluated using the numerical rating scale pain score. Radiographic outcomes were assessed with follow-up CT scans. The results were statistically analyzed using the Wilcoxon-Mann-Whitney test. Results The mean follow-up period was 13.4 months for the fluoroscopy group and 14.7 months for the iCT group. No surgical complications developed and no revisions were required. No statistically significant differences were found between the groups in surgical or clinical outcomes. However, the radiation exposure to the surgeons was significantly less with the iCT group (P Conclusions The use of iCT with spinal navigation for mini-open lateral Corpectomy for thoracolumbar burst fractures yields perioperative and clinical outcomes comparable to those using traditional fluoroscopy, with decreased radiation exposure to surgeons.
Howard S An - One of the best experts on this subject based on the ideXlab platform.
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Corpectomy versus discectomy for the treatment of multilevel cervical spine pathology a finite element model analysis
The Spine Journal, 2012Co-Authors: Mozammil Hussain, Howard S An, Ahmad Nassr, Raghu N Natarajan, Gunnar B J AnderssonAbstract:BACKGROUND CONTEXT: After multilevel fusions, construct failure because of pseudoarthrosis and instrumentation complications is a well-recognized clinical problem. Little is known about the biomechanics governing the cervical spine after different anterior reconstruction techniques, specifically the number of bone grafts and screws used and whether discectomies versus corpectomies have been performed. A few research groups have compared the efficacy of Corpectomy and discectomy procedures under common testing conditions; however, no quantitative stress measurements at graft-end plate and bone-screw interfaces have been reported to date. PURPOSE: To test the hypothesis that increasing the number of bone grafts and screws would yield a more stable construct and decrease the stresses at the graft-end plate and bone-screw interfaces. STUDY DESIGN: Stability of fusion constructs with three different multilevel reconstruction techniques. METHODS: A previously validated C3-T1 intact finite element model was modified to evaluate three different anterior C4-C7 fusion models: a two-level Corpectomy alone (one graft and four screws), a Corpectomy-discectomy (two grafts and six screws), and a three-level discectomy alone (three grafts and eight screws). Two unicortical screws were placed parallel to the corresponding end plates inside the vertebral bodies-C4 and C7 for the Corpectomy alone; C4, C6, and C7 for the Corpectomy-discectomy; and C4, C5, C6, and C7 for the discectomy alone. Range of motion, graft stresses, end plate stresses, and bone-screw stresses were evaluated. RESULTS: Although total construct motion decreased with an increasing number of bone grafts and screws, this was not significantly different between reconstruction techniques. Stresses in the bone grafts, end plates, and bone near screws decreased as a result of increasing the number of bone grafts and screws, thereby confirming the present study hypothesis. CONCLUSIONS: Although the chances of pseudarthrosis have been shown to be lower after multilevel cervical Corpectomy versus discectomy, because of fewer bone-graft interfaces required for healing, this benefit should be weighed against the higher bone-screw stresses, operating time, blood loss, and costs associated with Corpectomy. Future biomechanical studies focusing on Corpectomy and discectomy procedures in similar testing protocols are warranted to compare the findings presented here.
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biomechanical effects of anterior posterior and combined anterior posterior instrumentation techniques on the stability of a multilevel cervical Corpectomy construct a finite element model analysis
The Spine Journal, 2011Co-Authors: Mozammil Hussain, Howard S An, Ahmad Nassr, Raghu N Natarajan, Gunnar B J AnderssonAbstract:Abstract Background context Multilevel Corpectomy, with or without anterior instrumentation, has been associated with both graft and anterior screw-plate complications. The addition of posterior instrumentation after anterior fixation has been shown to increase the overall stiffness of fused segments and decrease the likelihood of instrumentation failure. Little biomechanical information exists for providing guidance in the selection of an appropriate instrumentation technique after a multilevel cervical Corpectomy. Clinical studies have also been inconclusive in choosing an optimum fixation strategy. Purpose To test the hypothesis that combined anterior-posterior fixation would lower the stresses on the bone-screw interfaces observed after an isolated anterior fixation and on the graft–end plate interfaces observed after an isolated posterior fixation. Study design A finite element (FE) analysis of a C4–C7 Corpectomy fusion with three different fixation techniques: anterior, posterior, and combined anterior-posterior. Methods A previously validated three-dimensional FE model of an intact C3–T1 segment was used. From this intact model, three additional instrumentation models were constructed using anterior (rigid screw-plate), posterior (rigid screw-rod), and combined anterior-posterior fixation techniques following a C4–C7 Corpectomy fusion. Construct stability at the cephalad and caudal levels of the Corpectomy was assessed. Results Biomechanical comparisons between these instrumentation techniques show the least amount of construct motion in the combined anterior-posterior instrumentation model. The use of both anterior and posterior fixation shields the graft–end plate and screw-bone interfaces from peak stresses as compared with an isolated anterior or an isolated posterior fixation, thereby supporting the hypothesis of this study. Conclusions A combined fixation technique should be balanced against increased operating room time and surgery costs because of dual anterior and posterior fixation and the increased risk of long anterior plating, such as dysphasia, plate or screw dislodgement, or migration. Our study suggests that the use of posterior fixation, whether alone or in combination with anterior fixation, infers comparable stability. Further studies are warranted to identify whether the current findings are consistent with other biomechanical studies.
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screw angulation affects bone screw stresses and bone graft load sharing in anterior cervical Corpectomy fusion with a rigid screw plate construct a finite element model study
The Spine Journal, 2009Co-Authors: Mozammil Hussain, Raghu N Natarajan, Gunnar B J Andersson, Amir H Fayyazi, Brian R Braaksma, Howard S AnAbstract:Abstract Background context Anterior Corpectomy and reconstruction with bone graft and a rigid screw-plate construct is an established procedure for treatment of cervical neural compression. Despite its reliability in relieving symptoms, there is a high rate of construct failure, especially in multilevel cases. Purpose There has been no study evaluating the biomechanical effects of screw angulation on construct stability; this study investigates the C4–C7 construct stability and load-sharing properties among varying screw angulations in a rigid plate-screw construct. Study design A finite element model of a two-level cervical Corpectomy with static anterior cervical plate. Methods A three-dimensional finite element (FE) model of an intact C3–T1 segment was developed and validated. From this intact model, a fusion model (two-level [C5, C6] anterior Corpectomy) was developed and validated. After Corpectomy, allograft interbody fusion with a rigid anterior screw-plate construct was created from C4 to C7. Five additional FE models were developed from the fusion model corresponding to five different combinations of screw angulations within the vertebral bodies (C4, C7): (0°, 0°), (5°, 5°), (10°, 10°), (15°, 15°), and (15°, 0°). The fifth fusion model was termed as a hybrid fusion model. Results The stability of a two-level Corpectomy reconstruction is not dependent on the position of the screws. Despite the locked screw-plate interface, some degree of load sharing is transmitted to the graft. The load seen by the graft and the shear stress at the bone-screw junction is dependent on the angle of the screws with respect to the end plate. Higher stresses are seen at more divergent angles, particularly at the lower level of the construct. Conclusion This study suggests that screw divergence from the end plates not only increases load transmission to the graft but also predisposes the screws to higher shear forces after Corpectomy reconstruction. In particular, the inferior screw demonstrated larger stress than the upper-level screws. In the proposed hybrid fusion model, lower stresses on the bone graft, end plates, and bone-screw interface were recorded, inferring lower construct failure (end-plate fractures and screw pullout) potential at the inferior construct end.
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enhancement of stability following anterior cervical Corpectomy a biomechanical study
Spine, 2004Co-Authors: Kern Singh, Alexander R Vaccaro, Eric P Lorenz, Howard S AnAbstract:STUDY DESIGN: An in vitro biomechanical study of various reconstructive techniques following decompression of the spondylotic cervical spine. OBJECTIVE.: To evaluate the biomechanical stability of anterior cervical plate fixation following three strategies of decompression for multilevel cervical spondylosis (three levels) of the cervical spine: three level discectomy, single Corpectomy and discectomy, and a two-level Corpectomy. SUMMARY OF BACKGROUND DATA: The main goals of surgical treatment for cervical myelopathy include adequate decompression and stabilization while maintaining or restoring cervical lordosis. Cervical decompression is often performed through a Corpectomy followed by strut-graft reconstruction. An anterior cervical plate with end-fixation (two points of fixation) is then used to span the construct. The authors propose an alternative to multilevel Corpectomy and long-segment end construct plate fixation. Often times, the cervical stenosis is confined to the area of the degenerative discs. As a result, the authors feel that either multilevel discectomy or a Corpectomy combined with discectomy followed by segmental plate fixation may provide adequate decompression with increased biomechanical rigidity as compared to cervical plate-constructs with end-fixation only. METHODS: Seven human cadaveric fresh-frozen cervical spines from C1-T1 were utilized. Three-dimensional motion analysis with an optical tracking device was used to determine motion following various reconstruction methods. All seven cervical spines underwent testing in a randomized order. The end construct model consisted of a Corpectomy at C4 and C5 with a polymethyl methacrylate strut graft and an anterior cervical PEAK (DePuy-AcroMed) plate. The two segmental constructs also utilized the PEAK plate with one construct undergoing discectomies at C3-C4, C4-C5, and C5-C6 with polymethyl methacrylate interbody grafts and the other segmental construct undergoing a discectomy at C3-C4 and a Corpectomy of C5. All specimens underwent a pure moment application of 2 Nm with regards to flexion-extension, lateral bending, and axial rotation. RESULTS.: The three-level discectomy and combined one-level discectomy and Corpectomy with segmental fixation was significantly more rigid in flexion-extension and lateral bending than the two-level Corpectomy with end-construct plate fixation (P < 0.05). There was no increase in stability during extension between the end construct (two-level Corpectomy) reconstruction model and the un-instrumented Corpectomy and grafted specimen. No difference was noted between the segmental constructs and the end-construct with regards to axial rotation. CONCLUSIONS: Cervical myelopathy is traditionally treated with a multilevel Corpectomy and an end-construct plate fixation spanning the strut graft. A large moment arm is generated at the ends of the construct, potentially leading to plate migration or dislodgment. Often times, adequate decompression can be achieved with either a multilevel discectomy or a combined discectomy and Corpectomy with segmental plate fixation. This study clearly demonstrates that segmental plate fixation affords a more biomechanically rigid method of reconstruction with regards to flexion-extension and lateral bending than end-construct plate fixation. The increased rigidity afforded by segmental fixation may significantly decrease the likelihood of plate dislodgement in the setting of anterior instrumentation alone following anterior alone, long segment reconstruction procedures.
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biomechanical comparison of cervical spine reconstructive techniques after a multilevel Corpectomy of the cervical spine
Spine, 2003Co-Authors: Kern Singh, Alexander R Vaccaro, Eric P Lorenz, Howard S AnAbstract:STUDY DESIGN: An in vitro biomechanical study of several reconstructive techniques after a two-level cervical Corpectomy. OBJECTIVES: To evaluate, compare, and quantitate the stability of several reconstructive strategies (anterior, posterior, or anterior/posterior with or without instrumentation) after a multilevel cervical Corpectomy. SUMMARY OF BACKGROUND DATA: Several clinical and biomechanical studies have questioned the stability of stand-alone long-segment anterior plate fixation after a multilevel (>or=2) Corpectomy. The large cantilever forces generated within the stabilized construct, particularly at the caudal screw-bone interface, have led to plate and screw dislodgement and the need for further surgical intervention. The addition of posterior segmental instrumentation has been shown to improve overall stability and decrease local stresses on the anterior fusion construct (graft and plate). MATERIALS AND METHODS: Seven fresh-frozen cadaveric human cervical spines (C1-T1) were harvested. The C1-C2 and C7-T1 vertebral bodies were embedded in poly-methylmethacrylate (PMMA). Three VICON cameras tracked three-dimensional segmental motions at the ends of the fusion construct after a two-level Corpectomy and placement of a strut graft with or without instrumentation. Pure moments (flexion/extension, lateral bending, and axial rotation) were applied to the C1 level of each specimen. The motion segments were loaded to a maximum of 2 Nm using dead weights. Testing was first performed on the intact specimens. Then, a two-level Corpectomy at the C4 and C5 levels was performed. A PMMA strut graft was then placed into the Corpectomy site. Biomechanical testing was then repeated among three different reconstruction techniques: 1) anterior cervical locking plate (PEAK; Depuy-Acromed, Raynham, MA) with dual unicortical screw fixation at C3 and C6; 2) posterior cervical instrumentation (Summit; Depuy-Acromed) using a 3.0-mm rod with segmental lateral mass screw fixation from C3 to C6; and 3) a combined anterior-posterior instrumentation using the anterior PEAK plate and posterior Summit rod system. RESULTS: In all pure moments tested (flexion/extension/lateral bending/axial rotation) the combined anterior-posterior instrumentation reconstruction model and the posterior-only instrumentation model were significantly more rigid than the anterior-only instrumentation model (P < 0.05). Interestingly, no statistically significant difference was noted between the combined anterior plate/posterior instrumentation model and the posterior instrumentation-only model. CONCLUSION: The biomechanical results obtained suggest that posterior segmental instrumentation confers significant stability to a multilevel cervical Corpectomy regardless of the presence or absence of anterior instrumentation. In cases in which the stability of a multilevel reconstruction procedure is tenuous, the surgeon should strongly consider the placement of segmental posterior instrumentation to significantly improve the overall stability of the fusion construct.
Zhongkai Yi - One of the best experts on this subject based on the ideXlab platform.
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anterior approach versus posterior approach with subtotal Corpectomy decompression and reconstruction of spine in the treatment of thoracolumbar burst fractures a prospective randomized controlled study
Journal of Spinal Disorders & Techniques, 2011Co-Authors: Zhiwen Chen, Zhongkai YiAbstract:Abstract STUDY DESIGN: A randomized, controlled follow-up study. OBJECTIVE: The objective of this study was to compare the results of anterior approach versus posterior approach with subtotal Corpectomy, decompression, and reconstruction of spine in the treatment of thoracolumbar burst fractures. SUMMARY OF BACKGROUND DATA: Burst fractures are frequently associated with instability or neurological deficit. Anterior subtotal Corpectomy, decompression, and reconstruction with instrumentation are an established method for a highly unstable burst fracture. In the past few years, subtotal Corpectomy, decompression, and reconstruction of spine could be completed by posterior approach. Posterior segmental pedicle screw instrumentation, with its more rigid fixation and less technically demanding, could offer potential advantages. METHODS: A total of 64 patients with thoracolumbar burst fractures were divided into 2 groups randomly. Group A was treated by anterior approach and group B was treated by posterior approach with subtotal Corpectomy, decompression, and reconstruction of spine. During the minimum 24 months (range, 24 to 72 mo) follow-up period, all patients were prospectively evaluated for clinical and radiologic outcomes. The intraoperative blood loss, operative time, complications of operation, pulmonary function, Frankel scale, and the American Spinal Injury Association (ASIA) motor score were used for clinical evaluation, whereas the heights of anterior edge of vertebral body and the Cobb angle were examined for radiologic outcome. RESULTS: All patients in this study achieved solid fusion, with significant neurological improvement. The intraoperative blood loss (P<0.05) and complications of operation were less, the operative time was shorter (P<0.05), and the pulmonary function after operation was better in the group B (P<0.05). The Frankel scale, the ASIA motor score, and the radiologic results were not significantly different (P<0.05) at all time points between the 2 groups A and B. But the 2 groups improved in their neurological function by approximately 1.3 Frankel grade and 15.6 ASIA motor scores at final follow-up. CONCLUSION: Anterior approach and posterior approach with subtotal Corpectomy, decompression, and reconstruction of spine are sufficient for surgical treatment of thoracolumbar burst fractures. Less intraoperative blood loss and complications, shorter operative time, and better pulmonary function after operation are the significant advantages of posterior surgery.
Richard G. Fessler - One of the best experts on this subject based on the ideXlab platform.
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Multilevel oblique corpectomies : Surgical indications and technique. Commentary
Neurosurgery, 2020Co-Authors: Michael Bruneau, Volker K. H. Sonntag, Edward C. Benzel, Jan Frederick Cornelius, Bernard George, Paul R. Cooper, Richard G. FesslerAbstract:OBJECTIVE: We describe extensively the multilevel oblique Corpectomy technique with its advantages, disadvantages, indications, and biomechanical effects. This procedure is an alternative to the anterior Corpectomy. METHODS: Multilevel oblique Corpectomy can be indicated in spondylotic myelopathy, whether or not it is associated with unilateral radiculopathy. Certain conditions must be fulfilled: anterior compression must be predominant, the spine must be kyphotic or straight, preoperative instability has to be excluded, and intervertebral discs have to be dehydrated and collapsed. RESULTS: The lateral aspect of the cervical spine is reached and the vertebral artery is controlled through a lateral approach. The lateral part of the pathological intervertebral discs is removed. Then, the lateral portion of the vertebral body is drilled to create an 8-mm wide vertical trench. When the posterior cortical bone as well as the superior and inferior end plates are reached, the microscope is moved obliquely to extend the drilling horizontally as long as required, up to the contralateral pedicle if necessary. Next, the posterior cortical bone and the posterior longitudinal ligament are removed to completely decompress the spinal cord. In the case of radiculopathy, the ipsilateral foramen can be completely opened by taking away the uncovertebral joint after its lateral aspect has been separated from the vertebral artery. CONCLUSION: The multilevel oblique Corpectomy technique allows wide anterior decompression of the spinal cord and complete unilateral nerve root decompression. Using this technique, the spinal stability is preserved and osteoarthrodesis is not required. Spinal motions are preserved and appear close to normal.
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minimally invasive thoracic Corpectomy surgical strategies for malignancy trauma and complex spinal pathologies
Minimally Invasive Surgery, 2012Co-Authors: Rohan R Lall, Zachary A Smith, Albert P Wong, Daniel D Miller, Richard G. FesslerAbstract:The rapid expansion of minimally invasive techniques for Corpectomy in the thoracic spine provides promise to redefine treatment options in this region. Techniques have evolved permitting anterior, lateral, posterolateral, and midline posterior Corpectomy in a minimally invasive fashion. We review the numerous techniques that have been described, including thoracoscopy, tubular retraction, and various instrumentation techniques. Minimally invasive techniques are compared to their open predecessors from a technical and complication standpoint. Advantages and disadvantages of different approaches are also considered, with an emphasis on surgical strategies and nuance.
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Cadaveric evaluation of minimally invasive posterolateral thoracic Corpectomy: a comparison of 3 approaches.
Journal of Spinal Disorders & Techniques, 2009Co-Authors: Alfred T. Ogden, Kurt M. Eichholz, John E. O'toole, Justin S. Smith, Gala, Jean-marc Voyadzis, Koichi Sugimoto, John K. Song, Richard G. FesslerAbstract:Study Design A cadaver study comparing 3 different minimally invasive approaches to the anterior thoracic spine. Objective To assess the feasibility of minimally invasive thoracic Corpectomy from a posterolateral approach and to compare surgical results from 3 approaches. Summary of Background Data Traditional posterolateral approaches to the thoracic spine are effective but are associated with a high rate of operative morbidity. Methods Thoracic corpectomies were performed using a modified tubular retractor starting at 3, 6, and 9 cm off of midline. Postoperative computed tomography scans were performed and analyzed to assess the extent of Corpectomy and ventral decompression. Results From 3 to 6 to 9 cm, a significant difference in extent of Corpectomy (65.8%, 81.5%, and 82.6%, P=0.02) and ventral decompression (83.6%, 90.4%, 94.6%, P=0.05) was noted between 3 cm and the more lateral approaches. The 9 cm approach required more rib resection and average working distances of 8.4 to 11.3 cm, which made the procedure more difficult technically and less suited to the length of standard instruments. Conclusions Minimally invasive thoracic Corpectomy is feasible and a 6 cm approach off of midline appears optimal.
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minimally invasive posterolateral thoracic Corpectomy cadaveric feasibility study and report of four clinical cases
Neurosurgery, 2009Co-Authors: John E Otoole, Alfred T. Ogden, Kurt M. Eichholz, John K. Song, Sean D Christie, Richard G. FesslerAbstract:OBJECTIVE: To demonstrate the feasibility of and initial clinical experience with a novel minimally invasive posterolateral thoracic Corpectomy technique. METHODS: Seven procedures were performed on 6 cadavers to determine the feasibility of thoracic Corpectomy using a minimally invasive approach. The posterolateral thoracic corpectomies were performed with expandable 22 mm diameter tubular retractor paramedian incisions. The posterolateral aspects of the vertebral bodies were accessed extrapleurally, and complete corpectomies were performed. Intraprocedural fluoroscopy and postoperative computed tomography were used to assess the degree of decompression. In addition, 2 clinical cases of T6 burst fracture, 1 T4-T5 plasmacytoma, and 1 T12 colon cancer metastasis were treated using this minimally invasive approach. RESULTS: In the cadaveric study, an average of 93% of the ventral canal and 80% of the corresponding vertebral body were removed. The pleura and intrathoracic contents were not violated. Adequate exposure was obtained to allow interbody grafting between the adjacent vertebral bodies. The procedures were successfully performed in the 4 clinical cases using a minimally invasive technique, and the patients demonstrated good outcomes. CONCLUSION: Based on this study, minimally invasive posterolateral thoracic Corpectomy safely and successfully allows complete spinal canal decompression without the tissue disruption associated with open thoracotomy. This approach may improve the complication rates that accompany open or even thoracoscopic approaches for thoracic Corpectomy and may even allow surgical intervention in patients with significant comorbidities.
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Anterior cervical discectomy and Corpectomy.
Neurosurgery, 2006Co-Authors: Mick J. Perez-cruet, Dino Samartzis, Richard G. FesslerAbstract:OBJECTIVE: The objective of this review article is to describe the authors' operative technique for performing anterior cervical Corpectomy and fusion. METHODS: The authors reviewed their operative technique and experience to clearly detail the general methods utilized to safely and effectively perform anterior cervical Corpectomy and fusion. Specific nuances peculiar to the authors' technique were identified and highlighted. RESULTS: The operative technique for anterior cervical Corpectomy, including nuances for enhancing ease or outcome of surgery, is described in detail. Drawings and photographs are included where appropriate to highlight specific aspects of the procedural technique. CONCLUSION: Anterior cervical Corpectomy and fusion is a well known technique that proceeds in a consistent and logical sequence of maneuvers. Specific technical nuances at various points enhance the ease and safety of the technique, as well as the completeness of the eventual result.
Volker K. H. Sonntag - One of the best experts on this subject based on the ideXlab platform.
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Biomechanical analysis of multilevel cervical Corpectomy and plate constructs.
Journal of neurosurgery, 2020Co-Authors: Randall W Porter, Robert H. Chamberlain, Neil R. Crawford, Sung Chan Park, Paul W Detwiler, Paul J Apostolides, Volker K. H. SonntagAbstract:The authors compared the biomechanical stability of two multilevel cervical constructs involving the placement of equal size anterior cervical plates (ACPs) after decompressive surgery: the first is placed after three-level Corpectomy with strut graft and the second after two-level Corpectomy and aggressive discectomy with strut graft. In addition, both constructs were evaluated with and without the application of a screw attaching the ACP to the strut graft to determine whether the additional screw enhanced stability in any mode of loading. Nondestructive repeated-measures in vitro flexibility tests were performed in human cadaveric cervical spines. Nonconstraining pure moments of up to 1.5 Nm were applied while recording three-dimensional angular motion stereophotogrammetrically at each level from C4-5 to C7-T1. Nine specimens underwent the three-level Corpectomy/strut graft procedure and eight specimens the two-level Corpectomy/discectomy strut graft procedure. Failures during testing eliminated two of the former specimens and three of the latter specimens from analysis. The construct applied after the two-level procedure allowed a significantly smaller normalized neutral zone during flexion-extension than the three-level construct (p = 0.04). Normalized elastic zone and range of motion were consistently smaller in the two- than in the three-level construct, but the differences were not significant. Addition of a screw to the strut graft significantly reduced motion in the three-level procedure-treated specimens during flexion and lateral bending but had no effect on two-level Corpectomy-treated specimens. The construct associated with the two-level Corpectomy/discectomy provided better immediate postoperative stability than that associated with the three-level Corpectomy. The addition of a screw to the strut graft conferred stability on the three-level construct but not the two-level construct.
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Biomechanical consequences of cervical spondylectomy versus Corpectomy.
Neurosurgery, 2020Co-Authors: Şeref Doğan, Volker K. H. Sonntag, Seungwon Baek, Neil R. CrawfordAbstract:To evaluate the differences in spinal stability and stabilizing potential of instrumentation after cervical Corpectomy and spondylectomy. Seven human cadaveric specimens were tested: 1) intact; 2) after grafted C5 Corpectomy and anterior C4-C6 plate; 3) after adding posterior C4-C6 screws/rods; 4) after extending posteriorly to C3-C7; 5) after grafted C5 spondylectomy, anterior C4-C6 plate, and posterior C4-C6 screws/rods; and 6) after extending posteriorly to C3-C7. Pure moments induced flexion, extension, lateral bending, and axial rotation; angular motion was recorded optically. After Corpectomy, anterior plating alone reduced the angular range of motion to a mean of 30% of normal, whereas added posterior short- or long-segment hardware reduced range of motion significantly more (P < 0.003), to less than 5% of normal. Constructs with posterior rods spanning C3-C7 were stiffer than constructs with posterior rods spanning C4-C6 during flexion, extension, and lateral bending (P < 0.05), but not during axial rotation (P > 0.07). Combined anterior and C4-C6 posterior fixation exhibited greater stiffness after Corpectomy than after spondylectomy during lateral bending (P = 0.019) and axial rotation (P = 0.001). Combined anterior and C3-C7 posterior fixation exhibited greater stiffness after Corpectomy than after spondylectomy during extension (P = 0.030) and axial rotation (P = 0.0001). Circumferential fixation provides more stability than anterior instrumentation alone after cervical Corpectomy. After Corpectomy or spondylectomy, long circumferential instrumentation provides better stability than short circumferential fixation except during axial rotation. Circumferential fixation more effectively prevents axial rotation after Corpectomy than after spondylectomy.
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Multilevel oblique corpectomies : Surgical indications and technique. Commentary
Neurosurgery, 2020Co-Authors: Michael Bruneau, Volker K. H. Sonntag, Edward C. Benzel, Jan Frederick Cornelius, Bernard George, Paul R. Cooper, Richard G. FesslerAbstract:OBJECTIVE: We describe extensively the multilevel oblique Corpectomy technique with its advantages, disadvantages, indications, and biomechanical effects. This procedure is an alternative to the anterior Corpectomy. METHODS: Multilevel oblique Corpectomy can be indicated in spondylotic myelopathy, whether or not it is associated with unilateral radiculopathy. Certain conditions must be fulfilled: anterior compression must be predominant, the spine must be kyphotic or straight, preoperative instability has to be excluded, and intervertebral discs have to be dehydrated and collapsed. RESULTS: The lateral aspect of the cervical spine is reached and the vertebral artery is controlled through a lateral approach. The lateral part of the pathological intervertebral discs is removed. Then, the lateral portion of the vertebral body is drilled to create an 8-mm wide vertical trench. When the posterior cortical bone as well as the superior and inferior end plates are reached, the microscope is moved obliquely to extend the drilling horizontally as long as required, up to the contralateral pedicle if necessary. Next, the posterior cortical bone and the posterior longitudinal ligament are removed to completely decompress the spinal cord. In the case of radiculopathy, the ipsilateral foramen can be completely opened by taking away the uncovertebral joint after its lateral aspect has been separated from the vertebral artery. CONCLUSION: The multilevel oblique Corpectomy technique allows wide anterior decompression of the spinal cord and complete unilateral nerve root decompression. Using this technique, the spinal stability is preserved and osteoarthrodesis is not required. Spinal motions are preserved and appear close to normal.
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Biomechanics of Cervical "Skip" Corpectomy Versus Standard Multilevel Corpectomy.
Journal of Spinal Disorders & Techniques, 2012Co-Authors: Murat Yilmaz, Volker K. H. Sonntag, Seungwon Baek, Kasim Zafer Yüksel, Anna G.u.s. Newcomb, Sedat Dalbayrak, Neil R. CrawfordAbstract:Study Design:In vitro biomechanical study of flexibility with finite-element simulation to estimate screw stresses.Objective:To compare cervical spinal stability after a standard plated 3-level Corpectomy with stability after a plated 3-level “skip” Corpectomy where the middle vertebra is left intac
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Biomechanical consequences of cervical spondylectomy versus Corpectomy.
Neurosurgery, 2008Co-Authors: Şeref Doğan, Volker K. H. Sonntag, Seungwon Baek, Neil R. CrawfordAbstract:OBJECTIVE: To evaluate the differences in spinal stability and stabilizing potential of instrumentation after cervical Corpectomy and spondylectomy. METHODS: Seven human cadaveric specimens were tested: 1) intact; 2) after grafted C5 Corpectomy and anterior C4-C6 plate; 3) after adding posterior C4-C6 screws/rods; 4) after extending posteriorly to C3-C7; 5) after grafted C5 spondylectomy, anterior C4-C6 plate, and posterior C4-C6 screws/rods; and 6) after extending posteriorly to C3-C7. Pure moments induced flexion, extension, lateral bending, and axial rotation; angular motion was recorded optically. RESULTS: After Corpectomy, anterior plating alone reduced the angular range of motion to a mean of 30% of normal, whereas added posterior short- or long-segment hardware reduced range of motion significantly more (P 0.07). Combined anterior and C4-C6 posterior fixation exhibited greater stiffness after Corpectomy than after spondylectomy during lateral bending (P = 0.019) and axial rotation (P = 0.001). Combined anterior and C3-C7 posterior fixation exhibited greater stiffness after Corpectomy than after spondylectomy during extension (P = 0.030) and axial rotation (P = 0.0001). CONCLUSION: Circumferential fixation provides more stability than anterior instrumentation alone after cervical Corpectomy. After Corpectomy or spondylectomy, long circumferential instrumentation provides better stability than short circumferential fixation except during axial rotation. Circumferential fixation more effectively prevents axial rotation after Corpectomy than after spondylectomy.
