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The Feasibility of Translaminar Screws in the Subaxial Cervical Spine: CT and Cadaveric Validation
Proceedings of the NASS 26th Annual Meeting / The Spine Journal 11 (2011) 1S–173S included in the fusion are unpredictable and can negatively impact sagittal alignment. Reciprocal changes (defined as postoperative alignment changes within spinal segments not included in the fusion following spinal reconstruction) have been described for all spinal regions except the cervical spine. PURPOSE: Evaluate postoperative reciprocal changes within the cervical spine following PSO. STUDY DESIGN/SETTING: Multicenter, retrospective radiographic analysis. PATIENT SAMPLE: Adult spinal deformity (ASD) patients with sagittal spinal malalignment (SSM) treated with thoracic or lumbar PSO from the multicenter International Spine Study Group PSO database. OUTCOME MEASURES: Radiographic cervical and spino-pelvic alignment following PSO. METHODS: Inclusion criteria: ASD patients, O18 years, preoperative sagittal vertical axis (SVA) O50 mm and cervical lordosis (C2-C7 Cobb) O15 treated with PSO for SSM. Exclusion criteria: neuromuscular, post-traumatic or tumor associated spinal deformity and ankylosing spondylitis. All patients had pre- and post-operative radiographs visualizing C2-pelvis and femoral heads. Radiographic measures included regional and global spino-pelvic parameters. Regional measures of spinal inclination (cervical, thoracic, lumbar) were determined based on best-fit linear approximation of the vertebral body centroids. RESULTS: 29 patients treated with 29 PSOs (26 lumbar and 3 thoracic) met inclusion criteria. PSO levels ranged from T7-L5 (most common level5L3; n512). Mean correction at PSO site was 26.5 , mean SVA improved from 134 mm to 50 mm (p!.001). CL decreased (29.1 to 21.4 , p!.001) and thoracic inclination (TI) decreased (23.7 to 11.0 , p!.001) following PSO. Similar improvement in postoperative cervical lordosis was demonstrated among patients with upper instrumented vertebra (UIV) cephalad to T9 (n512; 30.3 to 20.4 , p5.017) and UIV at or below T9 (n517; 28.2 to 22.1 , p5.012). Postoperative cervical inclination remained unchanged (preoperative513.3 , postoperative514.3 ; p5.554). T1 slope decreased following PSO (-36.9 to -31.8 , p5.006). Pearson correlation analysis demonstrated strong correlation between postoperative changes in SVA and TI (r50.82, p!.001) and moderate correlation between postoperative changes in TI and cervical lordosis (r50.39, p5.042). Postoperative change in cervical lordosis did not correlate with change in SVA (r50.18, p5.342). CONCLUSIONS: Cervical hyperlordosis is a compensatory mechanism utilized by patients with SSM to maintain horizontal gaze. SSM correction following PSO generates spontaneous decrease and relaxation of cervical lordosis. Favorable reciprocal changes in cervical alignment following PSO correlated with change in TI. TI alignment changes following PSO correlated strongly with SVA. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs. doi: 10.1016/j.spinee.2011.08.265
207. Operative Versus Nonoperative Management of Odontoid Fracture in the Elderly: Stochastic Simulation of Morbidity and Mortality Suneel Bhat1, Christopher Kepler, MD, MBA2, Kris Radcliff, MD3, Jeffrey Rihn, MD4, Todd Albert, MD5, Alexander Vaccaro, MD, PhD5; 1The Caladrius Institute, Columbia, MD, USA; 2New York, NY, USA; 3Ben Franklin House, Egg Harbor Township, NJ, USA; 4Thomas Jefferson University Hospital, The Rothman Institute, Philadelphia, PA, USA; 5 Rothman Institute, Philadelphia, PA, USA BACKGROUND CONTEXT: Fracture of the odontoid composes the majority of all spine fractures in the geriatric population. While consensus exists regarding treatment of Type I and Type III odontoid fractures, management of Type II fractures remains controversial. These fractures may be treated successfully either operatively or using conservative bracing, however the relative population benefits of these approaches remains unclear.
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PURPOSE: This study aimed to characterize the direct population implications on mortality and major complication rate of operative vs. non-operative management of traumatic Type II odontoid fracture in elderly patients. STUDY DESIGN/SETTING: This study utilized a decision tree model with Monte Carlo simulation analysis, with probabilities derived from a retrospective cohort analysis. PATIENT SAMPLE: We reviewed consecutive cases of isolated Type II odontoid fracture in patients 70 and older from June 1985 to July 2006 at a single Level 1 Trauma and Regional Spinal Cord Injury Center. OUTCOME MEASURES: Outcome measures included in the study were in-hospital mortality, airway complication, incidence of at least one major complication, and length of inpatient stay. METHODS: Consecutive cases of C2 fracture from June 1985 to July 2006 were retrospectively reviewed, and isolated Type II odontoid injuries in patients 70 and older were identified for surgical or non-surgical management, associated mortality, associated airway complication, or at least one associated major complication. A unique stochastic decision tree model based on probabilities derived from our data was developed, and a modified Monte Carlo simulation was conducted with each management approach using identical theoretical populations of 1,000,000 geriatric patients modeled from the 2008 US Census Estimates. Individually simulated patients accrued risk of Type II odontoid fracture, management associated airway complication or presence of at least one associated complication, and average length of inpatient stay. The simulation was iterated 10 times to achieve stable estimates. RESULTS: The incidence of Type II odontoid fracture for the US population over the age of 70 was approximated to 3.6 per 100,000, or 482 cases annually. In the elderly, operative management is associated with 96.32 deaths (95% CI 71.87 to 120.78), and non-operative management is associated with 264.20 deaths (95% CI 234.99 to 293.42); operative management result in a significant average annual reduction in mortality of 167.88 deaths. Non-operative management would on average prevent 55.04 airway complications and 247.69 major complications annually (both non-significant), and avoid 7477 inpatient person-days each year. CONCLUSIONS: Odontoid fracture in the elderly can be acceptably managed by both operative and non-operative approaches. While operative management will likely prevent approximately 167.88 deaths annually, non-operative management would avoid approximately 247.69 major treatment complications, 55.04 airway complications, and over 7400 inpatient days each year, in part secondary to increased mortality. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs. doi: 10.1016/j.spinee.2011.08.266
208. The Feasibility of Translaminar Screws in the Subaxial Cervical Spine: CT and Cadaveric Validation Woojin Cho, MD, PhD1, Jason Le, MD1, Adam Shimer, MD2, Brian Werner, MD3, Michael Iwanik3, John Glaser, MD4, Joshua Heller, MD1, Kai-Ming Fu, MD, PhD5, Francis Shen, MD6; 1 Charlottesville, VA, USA; 2University of Virginia School of Medicine, Department of Orthopeadic Surgery, Charlottesville, VA, USA; 3University of Virginia School of Medicine, Charlottesville, VA, USA; 4Medical University of South Carolina, Charleston, SC, USA; 5University of Virginia Hospital, Charlottesville, VA, USA; 6University of Virginia, Charlottesville, VA, USA BACKGROUND CONTEXT: The use of translaminar screws serve as a viable salvage method for complicated cases involving severe deformity, infection, osteoporosis, revision with altered anatomy, and tumors. To our understanding, the study of the feasibility of translaminar screw insertion in the entire subaxial cervical spine has not been carried out yet. PURPOSE: To report the Feasibility of Translaminar Screws in the Subaxial Cervical Spine. STUDY DESIGN/SETTING: Anatomy Study. PATIENT SAMPLE: 18 cadaveric spines were used.
All referenced figures and tables will be available at the Annual Meeting and will be included with the post-meeting online content.
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Proceedings of the NASS 26th Annual Meeting / The Spine Journal 11 (2011) 1S–173S
OUTCOME MEASURES: The translaminar screws were inserted in the cadaveric subaxial cervical spine, and the breakge of medial or lateral cortex was checked visually and with CT. METHODS: 18 cadaveric spines were harvested from C3 to C7 and 1-mm CT scans and 3D reconstructions were created to exclude any bony anomaly. 30 anatomically intact segments were collected (C3;2, C4;3, C5;3, C6;8, C7;14), and randomly arranged. 21 segments were physically separated at each vertebral level (Group S), while 9 segments were not separated from the vertebral column and left in situ (Group N-S). Using the trajectory proposed by the previous studies (Cho et al. 2010 CSRS, 2011 AAOS), and shown in Figure 1, translaminar screws were placed at each level. CT measurements along the simulated trajectory shown in Figure 2 were used to determine the screw diameter to be utilized. If the diameter chosen for the 2 screw was not feasible due to the 1 screw’s specific trajectory, only the 1 screw was inserted which was always placed to maximize bony purchase. 12 from Group S and 3 from Group N-S were chosen to receive the same diameter 1 and 2 screw. 9 from Group S and 6 from Group N-S received screws that were 0.5 mm larger in diameter. The 1 screw’s entry point was made above the inferior margin of the spinolaminar junction at a distance equal to the screw diameter used. The drill guide was pointed to the superomedial corner of the contralateral lateral mass, and carefully followed to avoid breaking the inner/outer laminar cortex. The hole length of the desired trajectory was measured. Then, based on the hole length measured, the 1 screws were selected and inserted. For the 2 screw, the entry point was made below the superior margin of the spinolaminar junction at a distance equal to the screw diameter used. The screw trajectory, created by the drill guide, was directed toward the superolateral corner of the contralateral lateral mass while going along the contralateral laminar slope. For the vertebrae from group S, breakage of either the medial or lateral cortex was visually confirmed. For each vertebra from group N-S, breakage of the medial or lateral cortex was checked using CT scans. RESULTS: The cortical breakage was shown in Figure 3 and Table 1. When 1 and 2 screws of the same size were used, medial cortex breakage was found 13% and 33% of the time, respectively. C7 was relatively safer than the other levels. With larger sized screws, medial cortex breakage was found in 47% and 46% of 1 and 2 screws, respectively. There were no facet injuries due to the screws in group N-S. CONCLUSIONS: Translaminar screw insertion in the subaxial cervical spine is feasible only when the lamina is thick enough to avoid any breakage that could lead to further complications. Otherwise, it is extremely dangerous; therefore, the authors don’t recommend inserting translaminar screws in the subaxial cervical spine except in some salvage cases in the presence of a thick lamina. Preoperative CT scans are mandatory to measure the thickness of the lamina. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs. doi: 10.1016/j.spinee.2011.08.267
209. Analysis of the Several Factors that may affect the Radiological and Clinical Outcome in Cervical Arthroplasty Chul-Woo Lee, MD; St. Peter’s Hospital, Seoul, Korea BACKGROUND CONTEXT: Spinal arthroplasty is becoming more widely performed in the treatment of degenerative cervical disc disease. Although there have been many studies to prove it’s efficacy and benefits over arthrodesis, some conditions which lead to undesirable consequences at the follow up(F/U) have been also reported. Surgeons planning to undertake cervical arthroplasty should be aware of the these factors and variables which can affect the outcome in order to get the consistent favorable result. PURPOSE: The purpose of this study was to investigate the possible factors that could affect the radiological and clinical outcome after cervical disc replacement and evaluate any statistical correlation between these factors and the postoperative radiologic and clinical outcome. STUDY DESIGN/SETTING: Retrospective, comparative radiological study.
PATIENT SAMPLE: 176 patients who recieved the cervical arthroplasty in total 234 level from march 2004 to december 2009(1 level: 129, 2 level : 36, 3 level: 11, 4 level: 1) were evaluated (mean F/U period : 30.75 months, minimum 12months.). OUTCOME MEASURES: Visual analog pain score (VAS), Neck Disability Index, and cervical spine radiogrphs were collected 3 times at preoperatively,early postoperatively (before 6 months) and last F/U. METHODS: We investigate the possible factors that could affect the radiological and clinical outcome after cervical disc replacement, focused on two main components, namely, factors which is related to preoperative status and technical factor. First, we examined preoperative factors, such as preoperative cervical sagittal alignment, preoperative ROM, degree of degeneration in cervical spine (disc height, facet degeneration, the presence of bony spur, calcification of ALL and PLL) and the number of involved arthroplasty level. Second, we then investigated technical factors, such as the size and position of the implant, increased disc height ratio by the device. We analyzed the statistical correlation between these factors and the postoperative radiologic and clinical outcome. RESULTS: Generally, the lordotic change in sagittal alignment (0.14 O 3.54 O-3.04) and the preservation of ROM (38.82 O32.86 O38.84) was noted after the procedure. Preoperative kyphotic group(N565) showed more evident lordotic change (4.79 O 7.37 -O 6.51, p5.02) than preoperative non-kyphotic group(N5155, 13.19 O 13.61 O 14.70) and preoperative limited ROM group(!30 degree, N558) showed the persistent increasement of ROM (21.37-O26.25-O28.09) compared to not limited ROM group(O30 degree, N5118, 47.13-O35.27-O42.93). (Figure 1) In terms of number of involved arthroplasty level, we also could see the corrective effect of kyphosis in sagittal alignment and increased ROM by 1 level and 2 level arthroplasty but 3 level arthroplasty group came up with the result showing more vulnerable to preoperative kyphosis and preoperative limited ROM.; rekyphosis(p5.01) and redecreasing tendency (p5.02) in late follow up period. (Figure 2,3) There was no statistically significant relationship between degree of degeneration and postoperative radiological and clinical outcome. But the groups that have more degeneration showed the tendency of postoperative kyphosis, the limitation of ROM and less decrease of VAS score at late follow up period (Figure 4). The position and size of the implant didn’t affect postoperative clinical result. Relatively anterior position of the implant made more lordotic realignment possible, but induced the more anterior migration of the device, the limitation of ROM and more chances of heterotrophic ossification(HO) at later follow up (Figure 5). More large size of the implant and relative high ratio of increase disc height (DH) were also as the causative factors to limit the ROM at index level (Figure 6). HO was found with higher incidence in the group that had the more degeneration and more small size of the implant (Figure 7). CONCLUSIONS: Cervical arthroplasty is the useful tool to restore the cervical alignment and ROM in even preoperative kyphosis and limited ROM group. But more careful patient selection for the cervical arthroplasty seems to be needed in the groups that have much degeneration and multi-level lesion. Appropriate size and positioning of the implant is mandatory to achieve good clinical and outcome in cervical arthroplasty. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs. doi: 10.1016/j.spinee.2011.08.268
210. Comparison of PEEK and Trabecular Metal Implants for Cervical Spinal Fusion in a Goat Model: Radiographic Versus Histological Assessment of Bone Bridging Regina Konz, PhD1, Sarina Sinclair, PhD2, John Dawson, PhD1, Roy Bloebaum, PhD2; 1Zimmer Spine, Minneapolis, MN, USA; 2Salt Lake City, UT, USA BACKGROUND CONTEXT: Anterior cervical discectomy and fusion (ACDF) is commonly used to treat cervical disc disease [1]. Recently, polyetheretherketone (PEEK) devices have gained popularity for ACDF
All referenced figures and tables will be available at the Annual Meeting and will be included with the post-meeting online content.
207. Operative Versus Nonoperative Management of Odontoid Fracture in the Elderly: Stochastic Simulation of Morbidity and Mortality Suneel Bhat1, Christopher Kepler, MD, MBA2, Kris Radcliff, MD3, Jeffrey Rihn, MD4, Todd Albert, MD5, Alexander Vaccaro, MD, PhD5; 1The Caladrius Institute, Columbia, MD, USA; 2New York, NY, USA; 3Ben Franklin House, Egg Harbor Township, NJ, USA; 4Thomas Jefferson University Hospital, The Rothman Institute, Philadelphia, PA, USA; 5 Rothman Institute, Philadelphia, PA, USA BACKGROUND CONTEXT: Fracture of the odontoid composes the majority of all spine fractures in the geriatric population. While consensus exists regarding treatment of Type I and Type III odontoid fractures, management of Type II fractures remains controversial. These fractures may be treated successfully either operatively or using conservative bracing, however the relative population benefits of these approaches remains unclear.
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PURPOSE: This study aimed to characterize the direct population implications on mortality and major complication rate of operative vs. non-operative management of traumatic Type II odontoid fracture in elderly patients. STUDY DESIGN/SETTING: This study utilized a decision tree model with Monte Carlo simulation analysis, with probabilities derived from a retrospective cohort analysis. PATIENT SAMPLE: We reviewed consecutive cases of isolated Type II odontoid fracture in patients 70 and older from June 1985 to July 2006 at a single Level 1 Trauma and Regional Spinal Cord Injury Center. OUTCOME MEASURES: Outcome measures included in the study were in-hospital mortality, airway complication, incidence of at least one major complication, and length of inpatient stay. METHODS: Consecutive cases of C2 fracture from June 1985 to July 2006 were retrospectively reviewed, and isolated Type II odontoid injuries in patients 70 and older were identified for surgical or non-surgical management, associated mortality, associated airway complication, or at least one associated major complication. A unique stochastic decision tree model based on probabilities derived from our data was developed, and a modified Monte Carlo simulation was conducted with each management approach using identical theoretical populations of 1,000,000 geriatric patients modeled from the 2008 US Census Estimates. Individually simulated patients accrued risk of Type II odontoid fracture, management associated airway complication or presence of at least one associated complication, and average length of inpatient stay. The simulation was iterated 10 times to achieve stable estimates. RESULTS: The incidence of Type II odontoid fracture for the US population over the age of 70 was approximated to 3.6 per 100,000, or 482 cases annually. In the elderly, operative management is associated with 96.32 deaths (95% CI 71.87 to 120.78), and non-operative management is associated with 264.20 deaths (95% CI 234.99 to 293.42); operative management result in a significant average annual reduction in mortality of 167.88 deaths. Non-operative management would on average prevent 55.04 airway complications and 247.69 major complications annually (both non-significant), and avoid 7477 inpatient person-days each year. CONCLUSIONS: Odontoid fracture in the elderly can be acceptably managed by both operative and non-operative approaches. While operative management will likely prevent approximately 167.88 deaths annually, non-operative management would avoid approximately 247.69 major treatment complications, 55.04 airway complications, and over 7400 inpatient days each year, in part secondary to increased mortality. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs. doi: 10.1016/j.spinee.2011.08.266
208. The Feasibility of Translaminar Screws in the Subaxial Cervical Spine: CT and Cadaveric Validation Woojin Cho, MD, PhD1, Jason Le, MD1, Adam Shimer, MD2, Brian Werner, MD3, Michael Iwanik3, John Glaser, MD4, Joshua Heller, MD1, Kai-Ming Fu, MD, PhD5, Francis Shen, MD6; 1 Charlottesville, VA, USA; 2University of Virginia School of Medicine, Department of Orthopeadic Surgery, Charlottesville, VA, USA; 3University of Virginia School of Medicine, Charlottesville, VA, USA; 4Medical University of South Carolina, Charleston, SC, USA; 5University of Virginia Hospital, Charlottesville, VA, USA; 6University of Virginia, Charlottesville, VA, USA BACKGROUND CONTEXT: The use of translaminar screws serve as a viable salvage method for complicated cases involving severe deformity, infection, osteoporosis, revision with altered anatomy, and tumors. To our understanding, the study of the feasibility of translaminar screw insertion in the entire subaxial cervical spine has not been carried out yet. PURPOSE: To report the Feasibility of Translaminar Screws in the Subaxial Cervical Spine. STUDY DESIGN/SETTING: Anatomy Study. PATIENT SAMPLE: 18 cadaveric spines were used.
All referenced figures and tables will be available at the Annual Meeting and will be included with the post-meeting online content.
108S
Proceedings of the NASS 26th Annual Meeting / The Spine Journal 11 (2011) 1S–173S
OUTCOME MEASURES: The translaminar screws were inserted in the cadaveric subaxial cervical spine, and the breakge of medial or lateral cortex was checked visually and with CT. METHODS: 18 cadaveric spines were harvested from C3 to C7 and 1-mm CT scans and 3D reconstructions were created to exclude any bony anomaly. 30 anatomically intact segments were collected (C3;2, C4;3, C5;3, C6;8, C7;14), and randomly arranged. 21 segments were physically separated at each vertebral level (Group S), while 9 segments were not separated from the vertebral column and left in situ (Group N-S). Using the trajectory proposed by the previous studies (Cho et al. 2010 CSRS, 2011 AAOS), and shown in Figure 1, translaminar screws were placed at each level. CT measurements along the simulated trajectory shown in Figure 2 were used to determine the screw diameter to be utilized. If the diameter chosen for the 2 screw was not feasible due to the 1 screw’s specific trajectory, only the 1 screw was inserted which was always placed to maximize bony purchase. 12 from Group S and 3 from Group N-S were chosen to receive the same diameter 1 and 2 screw. 9 from Group S and 6 from Group N-S received screws that were 0.5 mm larger in diameter. The 1 screw’s entry point was made above the inferior margin of the spinolaminar junction at a distance equal to the screw diameter used. The drill guide was pointed to the superomedial corner of the contralateral lateral mass, and carefully followed to avoid breaking the inner/outer laminar cortex. The hole length of the desired trajectory was measured. Then, based on the hole length measured, the 1 screws were selected and inserted. For the 2 screw, the entry point was made below the superior margin of the spinolaminar junction at a distance equal to the screw diameter used. The screw trajectory, created by the drill guide, was directed toward the superolateral corner of the contralateral lateral mass while going along the contralateral laminar slope. For the vertebrae from group S, breakage of either the medial or lateral cortex was visually confirmed. For each vertebra from group N-S, breakage of the medial or lateral cortex was checked using CT scans. RESULTS: The cortical breakage was shown in Figure 3 and Table 1. When 1 and 2 screws of the same size were used, medial cortex breakage was found 13% and 33% of the time, respectively. C7 was relatively safer than the other levels. With larger sized screws, medial cortex breakage was found in 47% and 46% of 1 and 2 screws, respectively. There were no facet injuries due to the screws in group N-S. CONCLUSIONS: Translaminar screw insertion in the subaxial cervical spine is feasible only when the lamina is thick enough to avoid any breakage that could lead to further complications. Otherwise, it is extremely dangerous; therefore, the authors don’t recommend inserting translaminar screws in the subaxial cervical spine except in some salvage cases in the presence of a thick lamina. Preoperative CT scans are mandatory to measure the thickness of the lamina. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs. doi: 10.1016/j.spinee.2011.08.267
209. Analysis of the Several Factors that may affect the Radiological and Clinical Outcome in Cervical Arthroplasty Chul-Woo Lee, MD; St. Peter’s Hospital, Seoul, Korea BACKGROUND CONTEXT: Spinal arthroplasty is becoming more widely performed in the treatment of degenerative cervical disc disease. Although there have been many studies to prove it’s efficacy and benefits over arthrodesis, some conditions which lead to undesirable consequences at the follow up(F/U) have been also reported. Surgeons planning to undertake cervical arthroplasty should be aware of the these factors and variables which can affect the outcome in order to get the consistent favorable result. PURPOSE: The purpose of this study was to investigate the possible factors that could affect the radiological and clinical outcome after cervical disc replacement and evaluate any statistical correlation between these factors and the postoperative radiologic and clinical outcome. STUDY DESIGN/SETTING: Retrospective, comparative radiological study.
PATIENT SAMPLE: 176 patients who recieved the cervical arthroplasty in total 234 level from march 2004 to december 2009(1 level: 129, 2 level : 36, 3 level: 11, 4 level: 1) were evaluated (mean F/U period : 30.75 months, minimum 12months.). OUTCOME MEASURES: Visual analog pain score (VAS), Neck Disability Index, and cervical spine radiogrphs were collected 3 times at preoperatively,early postoperatively (before 6 months) and last F/U. METHODS: We investigate the possible factors that could affect the radiological and clinical outcome after cervical disc replacement, focused on two main components, namely, factors which is related to preoperative status and technical factor. First, we examined preoperative factors, such as preoperative cervical sagittal alignment, preoperative ROM, degree of degeneration in cervical spine (disc height, facet degeneration, the presence of bony spur, calcification of ALL and PLL) and the number of involved arthroplasty level. Second, we then investigated technical factors, such as the size and position of the implant, increased disc height ratio by the device. We analyzed the statistical correlation between these factors and the postoperative radiologic and clinical outcome. RESULTS: Generally, the lordotic change in sagittal alignment (0.14 O 3.54 O-3.04) and the preservation of ROM (38.82 O32.86 O38.84) was noted after the procedure. Preoperative kyphotic group(N565) showed more evident lordotic change (4.79 O 7.37 -O 6.51, p5.02) than preoperative non-kyphotic group(N5155, 13.19 O 13.61 O 14.70) and preoperative limited ROM group(!30 degree, N558) showed the persistent increasement of ROM (21.37-O26.25-O28.09) compared to not limited ROM group(O30 degree, N5118, 47.13-O35.27-O42.93). (Figure 1) In terms of number of involved arthroplasty level, we also could see the corrective effect of kyphosis in sagittal alignment and increased ROM by 1 level and 2 level arthroplasty but 3 level arthroplasty group came up with the result showing more vulnerable to preoperative kyphosis and preoperative limited ROM.; rekyphosis(p5.01) and redecreasing tendency (p5.02) in late follow up period. (Figure 2,3) There was no statistically significant relationship between degree of degeneration and postoperative radiological and clinical outcome. But the groups that have more degeneration showed the tendency of postoperative kyphosis, the limitation of ROM and less decrease of VAS score at late follow up period (Figure 4). The position and size of the implant didn’t affect postoperative clinical result. Relatively anterior position of the implant made more lordotic realignment possible, but induced the more anterior migration of the device, the limitation of ROM and more chances of heterotrophic ossification(HO) at later follow up (Figure 5). More large size of the implant and relative high ratio of increase disc height (DH) were also as the causative factors to limit the ROM at index level (Figure 6). HO was found with higher incidence in the group that had the more degeneration and more small size of the implant (Figure 7). CONCLUSIONS: Cervical arthroplasty is the useful tool to restore the cervical alignment and ROM in even preoperative kyphosis and limited ROM group. But more careful patient selection for the cervical arthroplasty seems to be needed in the groups that have much degeneration and multi-level lesion. Appropriate size and positioning of the implant is mandatory to achieve good clinical and outcome in cervical arthroplasty. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs. doi: 10.1016/j.spinee.2011.08.268
210. Comparison of PEEK and Trabecular Metal Implants for Cervical Spinal Fusion in a Goat Model: Radiographic Versus Histological Assessment of Bone Bridging Regina Konz, PhD1, Sarina Sinclair, PhD2, John Dawson, PhD1, Roy Bloebaum, PhD2; 1Zimmer Spine, Minneapolis, MN, USA; 2Salt Lake City, UT, USA BACKGROUND CONTEXT: Anterior cervical discectomy and fusion (ACDF) is commonly used to treat cervical disc disease [1]. Recently, polyetheretherketone (PEEK) devices have gained popularity for ACDF
All referenced figures and tables will be available at the Annual Meeting and will be included with the post-meeting online content.