- Email: [email protected]
Effect of Lumbar Spinal Fusion on Adjacent Segment Discs—An In-Vivo Patient Study
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NASS 32nd Annual Meeting Proceedings / The Spine Journal 17 (2017) S111–S165
ses were performed between the three groups with statistical significance set to p<0.05. RESULTS: Following BTX-A injections, there was progressive paraspinal muscle atrophy and fatty infiltration that was confirmed on both MRI and histology. Muscle cross-sectional area (CSA) significantly decreased at each spinal level for the 3.5 Unit/kg and 8.0 Unit/kg BTX-A groups and was more pronounced in the higher dosage group (p<0.05). Fatty infiltration was also observed on the MR images in both BTX-A groups. Histological analysis confirmed the presence of adipocytes in the erector spinae muscles, validating the MRI fatty infiltration findings. There were no significant differences between groups for MRI analysis of disc height, disc signal intensity decreases or facet joint angle changes (p>0.05) at either the 8-week or 24week time point. There were also no significant differences between groups for histological analyses of the intervertebral discs or facet joints. A decrease in proteoglycan staining was noted in a select number of facet joints at the 24-week time period in both the 3.5 Unit/kg and 8.0 Unit/kg BTX-A groups, which was not present in the saline group; however, this finding was not statistically significant. CONCLUSIONS: In conclusion, this preliminary investigation demonstrates the ability to significantly induce morphological changes to the lumbar paraspinal muscles of the NZW rabbit, though there were no statistically significant changes to the intervertebral discs or facet joints. Additional studies investigating injections into different muscles (eg, multifidus) and extended time points are currently underway. FDA: N/A
change in Core Outcome Measures Index (COMI) score before surgery to follow-up. RESULTS: Some type of surgery (either decompression or fusion±stabilisation) was considered appropriate in 224 (47%) of the surgically-treated patients, inappropriate in 95 (20%), and uncertain in 156 (33%). There was a significant difference between the groups in the pattern of change in COMI score from preoperatively to follow-up (p<.001) whereby patients who were considered appropriate (A) or uncertain (U) candidates had greater improvements in COMI than those who were considered inappropriate (I) candidates. The minimal clinically important change (MCIC) score of 2.2 points for COMI was reached by 78% A, 83% U and 55% I cases (p<.001, I vs A and U). The odds of achieving the MCIC was 3 times greater in patients considered appropriate/uncertain for surgery than in those considered inappropriate (OR 3.4 95%CI 1.99–5.63). CONCLUSIONS: The results suggest a relationship between adherence to the AUC and outcome, and highlight the role of having sufficiently severe symptoms at baseline in order for surgery to be considered appropriate. The findings provide support for the use of AUCs in clinical practice, to guide indications for surgery, but the findings should be confirmed in prospective studies that also include a control group of non-surgical patients. (1) Mannion AF et al. (2014) Eur Spine J. 2014 Sep;23(9):1903-17. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs. https://doi.org/10.1016/j.spinee.2017.07.188
https://doi.org/10.1016/j.spinee.2017.07.334
Friday, October 27, 2017 9:00 AM – 10:00 AM Best Papers 145. Association Between Adherence to Appropriate Use Criteria and Postoperative Outcome in Patients Treated for Lumbar Degenerative Spondylolisthesis Francois Porchet, MD, PhD1, Felix Steiger, MSc1, Martin Aepli, MD1, Valerie Pittet, MEng, PhD, MSc2, John-Paul Vader, MD3, Dave O’Riordan, BS1, Francine B. Mariaux, MSc1, Anne F. Mannion, PhD1; 1Schulthess Clinic, Zürich, Switzerland; 2Institute of Social and Preventive Medicine, Lausanne, Switzerland; 3IUMSP/ CHUV, Lausanne, Switzerland BACKGROUND CONTEXT: In spine surgery, many treatment failures are attributable to poor patient selection and the application of inappropriate treatment. “Appropriate use criteria” (AUC) serve to help clarify the indications for a procedure. PURPOSE: This study aimed to use recently published AUC (1) to evaluate the appropriateness of surgery for lumbar degenerative spondylolisthesis (LDS) in a large group of patients and to examine the association between adherence to the criteria and postoperative outcome. STUDY DESIGN/SETTING: This was a retrospective analysis of prospectively collected data recorded in our Spine Outcomes database (linked to EUROSPINE’s Spine Tango Registry) from patients who had undergone LDS surgery in our clinic, 2005 to 2012. PATIENT SAMPLE: In total, 537 patients (age 69±10 y; 384 (72%) women) were eligible for inclusion, 98% of whom had completed a patient questionnaire preoperatively, 96% at 3-mo FU, 92% at 12-mo FU, 90% at 24-mo FU. We were able to apply the appropriateness criteria in 475/537 (88 %) patients with the necessary baseline data. OUTCOME MEASURES: Core Outcome Measures Index (COMI), with a 2.2-point improvement being considered a clinically important change score. METHODS: Appropriateness of the use of surgery in each patient was judged using published criteria (1). Appropriate use was evaluated in relation to the
146. Effect of Lumbar Spinal Fusion on Adjacent Segment Discs—An In-Vivo Patient Study Thomas D. Cha, MD, MBA1, Kamran Z. Khan, MS2, Yan Yu, MD, PhD1, Louis G. Jenis, MD1, James D. Kang, MD3, Kirkham B. Wood, MD4, Guoan Li, MD1; 1Massachusetts General Hospital, Boston, MA, USA; 2 Massachusetts General Hospital/Harvard Medical School, Boston, MA, USA; 3Brigham and Women’s Hospital, Boston, MA, USA; 4Stanford University School of Medicine Department of Orthopedic Surgery, Redwood City, CA, USA BACKGROUND CONTEXT: Degenerative disc disease (DDD) causes structural and mechanical failure of the intervertebral discs (IVDs) and is a major cause of low back pain. Spinal fusion surgery is a commonly performed surgical procedure for treating DDD with severe pain. However, longitudinal radiographic studies have demonstrated that fusion surgery accelerates disc degeneration in adjacent vertebral segments. Up to 80% of patients develop adjacent segment degeneration (ASD) as early as 1 year postoperatively, with an estimated 17%-36% of patients requiring reoperation within 5–10 years. It is assumed that mechanical factors initiate disc degeneration by exposing the adjacent segment disc tissue to abnormal and excessive loads, which alters the vertebral kinematics and accelerates ASD. However, no clear in-vivo data has been reported that shows the effects of spinal fusion on adjacent segment discs pre and postfusion. PURPOSE: To investigate adjacent segment disc deformation under weightbearing conditions in patients with low back pain and DDD before and after lumbar fusion surgery. STUDY DESIGN/SETTING: In-vivo patient study. PATIENT SAMPLE: Ten patients with disc degenerative disease at L4-S1 with severe pain were recruited for this study. OUTCOME MEASURES: Deformations of L3-4 disc were calculated using the changes in geometry between the endplates of L3 and L4 segments. Disc dimensions measured during MRI were used as reference. METHODS: Patients were MRI scanned and 3D anatomical models were constructed for each. Subjects were then imaged using a dual fluoroscopic imaging system at weight bearing standing, flexion and extension positions, before undergoing a fusion surgery at the L4-S1 segments. Five patients were imaged again 3 years after undergoing fusion surgery for postop analysis. Patient data were compared with 8 healthy control subjects whom were investigated the same way as the patients. We analyzed 9 points of interest on the endplate.
NASS 32nd Annual Meeting Proceedings / The Spine Journal 17 (2017) S111–S165 RESULTS: Our data show that the adjacent disc experienced significantly increased tensile and shear deformations both before and after the fusion surgery when compared to the normal, healthy subjects. Postfusion, the mean disc height was reduced by 1.15 mm. On average, 14% increase in shearing deformation at the adjacent disc was observed during the standing position. Overall, 13% and 12% increase in shearing was observed during flexion and extension positions, respectively, after the fusion surgery. Greater tensile deformations were observed at flexion and extension positions postoperatively when compared to preop and normal control subjects. Specifically, on average, an increase of 12.5% compressive deformation was observed in postop patients at the weight-bearing standing position. Lastly, during flexion and extension positions, significant increases in compression and tensile strains were observed, respectively. CONCLUSIONS: This study indicates that for patients with DDD, the adjacent segment disc experiences higher deformation compared to healthy subjects. However, fusion surgery further increased the disc deformation at the adjacent level. The anterior portion of the disc experienced greater deformation than other regions of the disc. Current literature suggests that increased shearing can lead to instability in the involved segment. Our findings are consistent with this and therefore, we believe the increased deformation postsurgery is a possible biomechanical mechanism that accelerates postoperative ASD. Therefore, fusion surgery should be limited to when dynamic biomechanical and clinical evidence of instability is present to minimize the interferences to adjacent segments and to improve longterm clinical outcomes. Future studies should investigate early disc degeneration after a fusion surgery using advanced MR imaging technique, such as T1ρ and T2 mapping. This will enable us to quantitatively evaluate disc degeneration and its association with altered disc deformation. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs. https://doi.org/10.1016/j.spinee.2017.07.189
147. Adjacent Segment Degeneration After Lumbar Total Disc Replacement: 5-Year Results of a Multicenter, Prospective, Randomized Study with Independent Radiographic Assessment Scott L. Blumenthal, MD1, Richard D. Guyer, MD1, Jack E. Zigler, MD1, Donna D. Ohnmeiss, PhD2; 1Texas Back Institute, Plano, TX, USA; 2Texas Back Institute Research Foundation, Plano, TX, USA BACKGROUND CONTEXT: One of the potential benefits of lumbar total disc replacement (TDR) over fusion for the treatment of painful disc degeneration is the possibility of reducing adjacent segment degeneration (ASD). There has been little investigation into this area in large prospective studies. PURPOSE: The purpose of this study was to analyze pre- to postoperative changes of the disc adjacent to the level receiving a TDR at 5-year follow-up. STUDY DESIGN/SETTING: The data were collected as part of a prospective, randomized, multicenter FDA-regulated trial. PATIENT SAMPLE: Patients from 14 sites were enrolled in the study: 218 assigned to the investigational group, activL® and 106 assigned to the control group, ProDisc-L. All patients were treated for single-level symptomatic disc degeneration nonresponsive to nonoperative care. OUTCOME MEASURES: Measurements made from the radiographs included adjacent segment degeneration based in the Kellgren-Lawrence scale and the scale described by Zigler et al. (JNS 2012), range of motion, disc height, and translation. METHODS: Flexion/extension, neutral lateral and anteroposterior radiographs were made at each study visit. Pre- and 5-year postoperative radiographs were available for 135 patients in the investigational group and 63 patients in the control group. All radiographs were evaluated by an independent lab specializing in image assessment. RESULTS: When compared to preoperative images, 8.8% of the investigational group and 19.0% of the control group had increased ASD scores at 5-year follow-up (p<.05). Results were the same using either the KellgrenLawrence or the Zigler ASD scale. Data were also analyzed calculating the
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percentage of patients with ASD for each degree of motion at the TDR level for 0° to 8°. For each additional degree of range of motion, there was a consistent decrease in the percentage of patients with ASD with values of (ranging from value for 0° to 8° respectively): 9.2%, 10.9%, 9.8%, 9.1%, 7.8%, 7.2%, 5.0%, 3.7%, and 2.3%. These values reflect that among patients with 1° of motion at the TDR level, 10.9% had increased degeneration at the adjacent segment at 5-year follow-up while patients with 8° of motion at the TDR level had a 2.3% occurrence of increased ASD. The rate of ASD was significantly greater in patients more than 40 years of age than those aged 40 years or less (19.6% vs 5.0%; p<.01; data pooled for investigational and control groups). CONCLUSIONS: The results of this prospective, 5-year follow-up study found that the rate of adjacent segment degeneration was 8.8% for the activL® device. This is similar to the rate of 9.2% reported in another TDR study with 5-year follow-up (Zigler et al., JNS, 2012). That study found ASD to be significantly less with TDR than with fusion. The rate of ASD declined with increasing range of motion at the TDR level, possibly suggesting a protective effect of motion. The higher rate of ASD among older patients may suggest that some changes in adjacent level discs may be attributable to the aging process. The current study adds further support that increased motion reduces the occurrence of adjacent segment degeneration. FDA DEVICE/DRUG STATUS: activL (Approved for this indication), ProDisc-L (Approved for this indication). https://doi.org/10.1016/j.spinee.2017.07.190
148. Effect of L4-Sacrum Fusion Alignment on Biomechanics of the Proximal Lumbar Segments in Sitting Postures Avinash G. Patwardhan, PhD1, Saeed Khayatzadeh, PhD2, Antonio A. Faundez, MD3, Robert M. Havey, MS4, Leonard I. Voronov, MD, PhD5, Alexander J. Ghanayem, MD1, Jean-Charles Le Huec, MD6; 1Loyola University Medical Center, Department of Orthopaedic Surgery, Maywood, IL, USA; 2Orthopedic Biomechanics Lab, Hines, IL, USA; 3Geneve, Switzerland; 4IL, USA; 5 Loyola University Chicago/Edward Hines Jr. VA Hospital, Hines, IL, USA; 6Bordeaux, France BACKGROUND CONTEXT: L4-Sacrum is the most prevalent site of spinal fusions for painful degenerative conditions in adults. The recommended lordosis angle across the fused segments is based on studies of standing alignment even though adults are spending increasing amount of time sitting at work and home. The median number of hours spent sitting are as high as 7 hours in an 8-hour work day for occupations such as accountants, administrators, architects, truck drivers, software developers and analysts, to name a few. Anecdotally, patients who have experienced no pain while sitting before surgery frequently report sitting intolerance and pain after fusion. PURPOSE: In this study, we asked: (1) how do different sitting postures alter the lumbosacral spinal alignment? and (2) what impact will this have on the mechanical loading at proximal lumbar segments adjacent to L4-Sacrum fusion? STUDY DESIGN/SETTING: A combination of (1) radiographic study of postural influence on lumbopelvic alignment, and (2) numerical simulation of postfusion postural accommodation. PATIENT SAMPLE: Eleven asymptomatic adults. OUTCOME MEASURES: Lumbopelvic sagittal alignment parameters, postural compensation in degrees. METHODS: Postural influence on lumbosacral sagittal alignment was assessed by analyzing full-length radiographs of 11 asymptomatic volunteers taken in three postures: (i) standing, (ii) erect-sitting, and (iii) slumpedsitting. Next, for each subject we numerically simulated the postfusion postural compensation needed to accommodate sitting postures after L4-Sacrum segments were immobilized duplicating their lordosis angle in the standing radiograph. The postfusion accommodation was simulated by forcing the L1 vertebra to maintain its prefusion position and angular alignment, thereby maintaining the postfusion alignment of the thoracic and cervical spine as near their prefusion alignment as possible.
NASS 32nd Annual Meeting Proceedings / The Spine Journal 17 (2017) S111–S165
ses were performed between the three groups with statistical significance set to p<0.05. RESULTS: Following BTX-A injections, there was progressive paraspinal muscle atrophy and fatty infiltration that was confirmed on both MRI and histology. Muscle cross-sectional area (CSA) significantly decreased at each spinal level for the 3.5 Unit/kg and 8.0 Unit/kg BTX-A groups and was more pronounced in the higher dosage group (p<0.05). Fatty infiltration was also observed on the MR images in both BTX-A groups. Histological analysis confirmed the presence of adipocytes in the erector spinae muscles, validating the MRI fatty infiltration findings. There were no significant differences between groups for MRI analysis of disc height, disc signal intensity decreases or facet joint angle changes (p>0.05) at either the 8-week or 24week time point. There were also no significant differences between groups for histological analyses of the intervertebral discs or facet joints. A decrease in proteoglycan staining was noted in a select number of facet joints at the 24-week time period in both the 3.5 Unit/kg and 8.0 Unit/kg BTX-A groups, which was not present in the saline group; however, this finding was not statistically significant. CONCLUSIONS: In conclusion, this preliminary investigation demonstrates the ability to significantly induce morphological changes to the lumbar paraspinal muscles of the NZW rabbit, though there were no statistically significant changes to the intervertebral discs or facet joints. Additional studies investigating injections into different muscles (eg, multifidus) and extended time points are currently underway. FDA: N/A
change in Core Outcome Measures Index (COMI) score before surgery to follow-up. RESULTS: Some type of surgery (either decompression or fusion±stabilisation) was considered appropriate in 224 (47%) of the surgically-treated patients, inappropriate in 95 (20%), and uncertain in 156 (33%). There was a significant difference between the groups in the pattern of change in COMI score from preoperatively to follow-up (p<.001) whereby patients who were considered appropriate (A) or uncertain (U) candidates had greater improvements in COMI than those who were considered inappropriate (I) candidates. The minimal clinically important change (MCIC) score of 2.2 points for COMI was reached by 78% A, 83% U and 55% I cases (p<.001, I vs A and U). The odds of achieving the MCIC was 3 times greater in patients considered appropriate/uncertain for surgery than in those considered inappropriate (OR 3.4 95%CI 1.99–5.63). CONCLUSIONS: The results suggest a relationship between adherence to the AUC and outcome, and highlight the role of having sufficiently severe symptoms at baseline in order for surgery to be considered appropriate. The findings provide support for the use of AUCs in clinical practice, to guide indications for surgery, but the findings should be confirmed in prospective studies that also include a control group of non-surgical patients. (1) Mannion AF et al. (2014) Eur Spine J. 2014 Sep;23(9):1903-17. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs. https://doi.org/10.1016/j.spinee.2017.07.188
https://doi.org/10.1016/j.spinee.2017.07.334
Friday, October 27, 2017 9:00 AM – 10:00 AM Best Papers 145. Association Between Adherence to Appropriate Use Criteria and Postoperative Outcome in Patients Treated for Lumbar Degenerative Spondylolisthesis Francois Porchet, MD, PhD1, Felix Steiger, MSc1, Martin Aepli, MD1, Valerie Pittet, MEng, PhD, MSc2, John-Paul Vader, MD3, Dave O’Riordan, BS1, Francine B. Mariaux, MSc1, Anne F. Mannion, PhD1; 1Schulthess Clinic, Zürich, Switzerland; 2Institute of Social and Preventive Medicine, Lausanne, Switzerland; 3IUMSP/ CHUV, Lausanne, Switzerland BACKGROUND CONTEXT: In spine surgery, many treatment failures are attributable to poor patient selection and the application of inappropriate treatment. “Appropriate use criteria” (AUC) serve to help clarify the indications for a procedure. PURPOSE: This study aimed to use recently published AUC (1) to evaluate the appropriateness of surgery for lumbar degenerative spondylolisthesis (LDS) in a large group of patients and to examine the association between adherence to the criteria and postoperative outcome. STUDY DESIGN/SETTING: This was a retrospective analysis of prospectively collected data recorded in our Spine Outcomes database (linked to EUROSPINE’s Spine Tango Registry) from patients who had undergone LDS surgery in our clinic, 2005 to 2012. PATIENT SAMPLE: In total, 537 patients (age 69±10 y; 384 (72%) women) were eligible for inclusion, 98% of whom had completed a patient questionnaire preoperatively, 96% at 3-mo FU, 92% at 12-mo FU, 90% at 24-mo FU. We were able to apply the appropriateness criteria in 475/537 (88 %) patients with the necessary baseline data. OUTCOME MEASURES: Core Outcome Measures Index (COMI), with a 2.2-point improvement being considered a clinically important change score. METHODS: Appropriateness of the use of surgery in each patient was judged using published criteria (1). Appropriate use was evaluated in relation to the
146. Effect of Lumbar Spinal Fusion on Adjacent Segment Discs—An In-Vivo Patient Study Thomas D. Cha, MD, MBA1, Kamran Z. Khan, MS2, Yan Yu, MD, PhD1, Louis G. Jenis, MD1, James D. Kang, MD3, Kirkham B. Wood, MD4, Guoan Li, MD1; 1Massachusetts General Hospital, Boston, MA, USA; 2 Massachusetts General Hospital/Harvard Medical School, Boston, MA, USA; 3Brigham and Women’s Hospital, Boston, MA, USA; 4Stanford University School of Medicine Department of Orthopedic Surgery, Redwood City, CA, USA BACKGROUND CONTEXT: Degenerative disc disease (DDD) causes structural and mechanical failure of the intervertebral discs (IVDs) and is a major cause of low back pain. Spinal fusion surgery is a commonly performed surgical procedure for treating DDD with severe pain. However, longitudinal radiographic studies have demonstrated that fusion surgery accelerates disc degeneration in adjacent vertebral segments. Up to 80% of patients develop adjacent segment degeneration (ASD) as early as 1 year postoperatively, with an estimated 17%-36% of patients requiring reoperation within 5–10 years. It is assumed that mechanical factors initiate disc degeneration by exposing the adjacent segment disc tissue to abnormal and excessive loads, which alters the vertebral kinematics and accelerates ASD. However, no clear in-vivo data has been reported that shows the effects of spinal fusion on adjacent segment discs pre and postfusion. PURPOSE: To investigate adjacent segment disc deformation under weightbearing conditions in patients with low back pain and DDD before and after lumbar fusion surgery. STUDY DESIGN/SETTING: In-vivo patient study. PATIENT SAMPLE: Ten patients with disc degenerative disease at L4-S1 with severe pain were recruited for this study. OUTCOME MEASURES: Deformations of L3-4 disc were calculated using the changes in geometry between the endplates of L3 and L4 segments. Disc dimensions measured during MRI were used as reference. METHODS: Patients were MRI scanned and 3D anatomical models were constructed for each. Subjects were then imaged using a dual fluoroscopic imaging system at weight bearing standing, flexion and extension positions, before undergoing a fusion surgery at the L4-S1 segments. Five patients were imaged again 3 years after undergoing fusion surgery for postop analysis. Patient data were compared with 8 healthy control subjects whom were investigated the same way as the patients. We analyzed 9 points of interest on the endplate.
NASS 32nd Annual Meeting Proceedings / The Spine Journal 17 (2017) S111–S165 RESULTS: Our data show that the adjacent disc experienced significantly increased tensile and shear deformations both before and after the fusion surgery when compared to the normal, healthy subjects. Postfusion, the mean disc height was reduced by 1.15 mm. On average, 14% increase in shearing deformation at the adjacent disc was observed during the standing position. Overall, 13% and 12% increase in shearing was observed during flexion and extension positions, respectively, after the fusion surgery. Greater tensile deformations were observed at flexion and extension positions postoperatively when compared to preop and normal control subjects. Specifically, on average, an increase of 12.5% compressive deformation was observed in postop patients at the weight-bearing standing position. Lastly, during flexion and extension positions, significant increases in compression and tensile strains were observed, respectively. CONCLUSIONS: This study indicates that for patients with DDD, the adjacent segment disc experiences higher deformation compared to healthy subjects. However, fusion surgery further increased the disc deformation at the adjacent level. The anterior portion of the disc experienced greater deformation than other regions of the disc. Current literature suggests that increased shearing can lead to instability in the involved segment. Our findings are consistent with this and therefore, we believe the increased deformation postsurgery is a possible biomechanical mechanism that accelerates postoperative ASD. Therefore, fusion surgery should be limited to when dynamic biomechanical and clinical evidence of instability is present to minimize the interferences to adjacent segments and to improve longterm clinical outcomes. Future studies should investigate early disc degeneration after a fusion surgery using advanced MR imaging technique, such as T1ρ and T2 mapping. This will enable us to quantitatively evaluate disc degeneration and its association with altered disc deformation. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs. https://doi.org/10.1016/j.spinee.2017.07.189
147. Adjacent Segment Degeneration After Lumbar Total Disc Replacement: 5-Year Results of a Multicenter, Prospective, Randomized Study with Independent Radiographic Assessment Scott L. Blumenthal, MD1, Richard D. Guyer, MD1, Jack E. Zigler, MD1, Donna D. Ohnmeiss, PhD2; 1Texas Back Institute, Plano, TX, USA; 2Texas Back Institute Research Foundation, Plano, TX, USA BACKGROUND CONTEXT: One of the potential benefits of lumbar total disc replacement (TDR) over fusion for the treatment of painful disc degeneration is the possibility of reducing adjacent segment degeneration (ASD). There has been little investigation into this area in large prospective studies. PURPOSE: The purpose of this study was to analyze pre- to postoperative changes of the disc adjacent to the level receiving a TDR at 5-year follow-up. STUDY DESIGN/SETTING: The data were collected as part of a prospective, randomized, multicenter FDA-regulated trial. PATIENT SAMPLE: Patients from 14 sites were enrolled in the study: 218 assigned to the investigational group, activL® and 106 assigned to the control group, ProDisc-L. All patients were treated for single-level symptomatic disc degeneration nonresponsive to nonoperative care. OUTCOME MEASURES: Measurements made from the radiographs included adjacent segment degeneration based in the Kellgren-Lawrence scale and the scale described by Zigler et al. (JNS 2012), range of motion, disc height, and translation. METHODS: Flexion/extension, neutral lateral and anteroposterior radiographs were made at each study visit. Pre- and 5-year postoperative radiographs were available for 135 patients in the investigational group and 63 patients in the control group. All radiographs were evaluated by an independent lab specializing in image assessment. RESULTS: When compared to preoperative images, 8.8% of the investigational group and 19.0% of the control group had increased ASD scores at 5-year follow-up (p<.05). Results were the same using either the KellgrenLawrence or the Zigler ASD scale. Data were also analyzed calculating the
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percentage of patients with ASD for each degree of motion at the TDR level for 0° to 8°. For each additional degree of range of motion, there was a consistent decrease in the percentage of patients with ASD with values of (ranging from value for 0° to 8° respectively): 9.2%, 10.9%, 9.8%, 9.1%, 7.8%, 7.2%, 5.0%, 3.7%, and 2.3%. These values reflect that among patients with 1° of motion at the TDR level, 10.9% had increased degeneration at the adjacent segment at 5-year follow-up while patients with 8° of motion at the TDR level had a 2.3% occurrence of increased ASD. The rate of ASD was significantly greater in patients more than 40 years of age than those aged 40 years or less (19.6% vs 5.0%; p<.01; data pooled for investigational and control groups). CONCLUSIONS: The results of this prospective, 5-year follow-up study found that the rate of adjacent segment degeneration was 8.8% for the activL® device. This is similar to the rate of 9.2% reported in another TDR study with 5-year follow-up (Zigler et al., JNS, 2012). That study found ASD to be significantly less with TDR than with fusion. The rate of ASD declined with increasing range of motion at the TDR level, possibly suggesting a protective effect of motion. The higher rate of ASD among older patients may suggest that some changes in adjacent level discs may be attributable to the aging process. The current study adds further support that increased motion reduces the occurrence of adjacent segment degeneration. FDA DEVICE/DRUG STATUS: activL (Approved for this indication), ProDisc-L (Approved for this indication). https://doi.org/10.1016/j.spinee.2017.07.190
148. Effect of L4-Sacrum Fusion Alignment on Biomechanics of the Proximal Lumbar Segments in Sitting Postures Avinash G. Patwardhan, PhD1, Saeed Khayatzadeh, PhD2, Antonio A. Faundez, MD3, Robert M. Havey, MS4, Leonard I. Voronov, MD, PhD5, Alexander J. Ghanayem, MD1, Jean-Charles Le Huec, MD6; 1Loyola University Medical Center, Department of Orthopaedic Surgery, Maywood, IL, USA; 2Orthopedic Biomechanics Lab, Hines, IL, USA; 3Geneve, Switzerland; 4IL, USA; 5 Loyola University Chicago/Edward Hines Jr. VA Hospital, Hines, IL, USA; 6Bordeaux, France BACKGROUND CONTEXT: L4-Sacrum is the most prevalent site of spinal fusions for painful degenerative conditions in adults. The recommended lordosis angle across the fused segments is based on studies of standing alignment even though adults are spending increasing amount of time sitting at work and home. The median number of hours spent sitting are as high as 7 hours in an 8-hour work day for occupations such as accountants, administrators, architects, truck drivers, software developers and analysts, to name a few. Anecdotally, patients who have experienced no pain while sitting before surgery frequently report sitting intolerance and pain after fusion. PURPOSE: In this study, we asked: (1) how do different sitting postures alter the lumbosacral spinal alignment? and (2) what impact will this have on the mechanical loading at proximal lumbar segments adjacent to L4-Sacrum fusion? STUDY DESIGN/SETTING: A combination of (1) radiographic study of postural influence on lumbopelvic alignment, and (2) numerical simulation of postfusion postural accommodation. PATIENT SAMPLE: Eleven asymptomatic adults. OUTCOME MEASURES: Lumbopelvic sagittal alignment parameters, postural compensation in degrees. METHODS: Postural influence on lumbosacral sagittal alignment was assessed by analyzing full-length radiographs of 11 asymptomatic volunteers taken in three postures: (i) standing, (ii) erect-sitting, and (iii) slumpedsitting. Next, for each subject we numerically simulated the postfusion postural compensation needed to accommodate sitting postures after L4-Sacrum segments were immobilized duplicating their lordosis angle in the standing radiograph. The postfusion accommodation was simulated by forcing the L1 vertebra to maintain its prefusion position and angular alignment, thereby maintaining the postfusion alignment of the thoracic and cervical spine as near their prefusion alignment as possible.