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MRI-Based Determination of Convex or Concave Surgical Approach for Lateral Lumbar Interbody Fusion in Lumbar Degenerative Scoliosis
Proceedings of the NASS 30th Annual Meeting / The Spine Journal 15 (2015) 87S–267S
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mortality were PVD, bleeding disorder and prior neuromuscular injury. Mortality was also associated with extending the fusion to the pelvis. These factors should be considered carefully during medical optimization and risk stratification. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
http://dx.doi.org/10.1016/j.spinee.2015.07.177
147. MRI-Based Determination of Convex or Concave Surgical Approach for Lateral Lumbar Interbody Fusion in Lumbar Degenerative Scoliosis Myung-Hoon Shin, MD; Seoul, South Korea
146. Biomechanical Assessment of L5 Nerve Root Strain in a 3D Print High-Grade Spondylolisthesis Model Keun Heng Huo, MD1, Alexander Peterson, BA2, S. Samuel Bederman, MD, PhD, FRCSC3, Lauren Nguyen4; 1University of California Irvine, Orange, CA, US; 2Marina Del Rey, CA, US; 3University of California Irvine Department of Orthopaedic Surgery, Orange, CA, US; 4Stanford, CA, US BACKGROUND CONTEXT: The surgical reduction of high-grade spondylolisthesis remains controversial given the potential for intraoperative nerve injury. Various reduction methods, including rotational and translational variants, have been described in the literature but no objective comparison study assessing the respective nerve strain exists in the current literature. PURPOSE: The purpose of our study was to compare the nerve strain of the L5 nerve root, for both a rotational and translational reduction maneuver. STUDY DESIGN/SETTING: A 3D printed lumbar spine and sacrum, rendered from the CT scan of a patient with grade 3 spondylolisthesis, was utilized. A custom testing jig situating the spine in the prone position to simulate intra-operative layout allowed for two reduction techniques: translation-dominant and rotation-dominant. Two starting positions (75% slip) were set at neutral (A1) and 15 of relative lordosis (A2). Two ending positions (0% slip) were set at neutral (B1) and 15 of relative kyphosis (B2). This allowed for four different reduction paths (A1-B1, A1-B2, A2-B1, A2-B2). PATIENT SAMPLE: The patient sample comprises a single patient with Grade 3 spondylolisthesis, whose CT scan was 3D printed for our model. Although only one patient’s spine was utilized, by incorporating variable aspects to approach the reduction, such as the reduction maneuver and different inclinations for the starting/ending points, the sample could be tested under multiple different scenarios to further expand the study’s clinical application. OUTCOME MEASURES: The primary outcome measure was nerve strain, calculated from the variable length of the nerve between the two points along the anatomic course of the L5 nerve root on the L5 vertebral body and the sacrum during reduction. METHODS: After mounting the 3D model onto the custom jig, a 3D motion-tracking device was used to measure the distance between two anatomic reference points used to represent L5 length during reduction from 75% to 0% slip. To ensure repeatability, two different investigators repeated all reductions 10 times each. Repeated-measures ANOVA and paired t-tests were used in statistical analysis. This methodology was applied for all four reduction paths in both the rotation-dominant and translational-dominant reductions. RESULTS: On average, across all paths, rotatory reduction produced 34.4% less L5 nerve strain than the translational reduction. The lordotic starting position led to 7.9% less nerve strain than neutral. The kyphotic ending position produced 15.1% more strain across all starting positions and reduction maneuvers. The A2-B1 path with rotatory reduction produced the least nerve strain. CONCLUSIONS: Based on this study, a rotation-dominant reduction with the patient in prone lordotic positioning may minimize L5 injury during surgical reduction of spondylolisthesis. Clinical studies are needed to confirm these findings.
http://dx.doi.org/10.1016/j.spinee.2015.07.178
BACKGROUND CONTEXT: The lateral lumbar interbody fusion (LLIF) is increasingly employed to treat lumbar degenerative scoliosis (LDS). Concerns remain about the transpsoas dissection-related complications. However, there is little information documenting which side is more appropriate for safety, the concave or the convex side. PURPOSE: The authors undertook this radiologic study to suggest the optimal approach side for LLIF by comparing the safe zone and psoas muscle on the concave and convex side of the patients with LDS. STUDY DESIGN/SETTING: Comparative MR image analysis. PATIENT SAMPLE: We retrospectively constructed cohort of the patient who had been diagnosed with LDS in out-patient clinic during the period from January 2012 to December 2013. The non-scoliosis group included 35 patients, the levoscoliosis group had 33 patients and the dextroscoliosis group had 35 patients. OUTCOME MEASURES: Ventral overlap is a distance between the anterior border of the vertebral body and the posterior border of the retroperitoneal vessels (aorta, common iliac artery, vena cava or common iliac vein depending on its level). Dorsal overlap is a distance between the posterior border of the vertebral body and the ventral edge of the nerve roots. Using these parameters, distance of the safe zone (a-(bþc)) at each level and percentage of safe zone to each vertebral body were calculated. Cross-sectional area (CSA), fatty infiltration (FI) rate and thickness of psoas muscle on both concave and convex side at each level was evaluated. METHODS: The differences between the two groups were assessed by means of the student’s t-test or Mann-Whitney U test according to the result of the Kolmogorov-Smirnov test. A p-value less than or equal to 0.05 was considered to indicate statistical significance. RESULTS: The ventral overlap on the convex side was decreased at L3-4 and L4-5 level in the levoscoliosis group (p 5 0.05 and 0.01, respectively) and at L2-3 and L3-4 level in the dextroscoliosis group (p 5 0.01 and 0.03, respectively) while the dorsal overlap showed no significant changes on both sides in both groups. In the levoscoliosis group, the convex side at L3-4 and L4-5 level presented greater safe zone than the nonscoliosis group (76.11% vs 74.00% at L3-4; p 5 0.02, 69.37% vs 63.16% at L45; p 5 0.00). Likely, the convex side at L2-3, L3-4 and L4-5 level in the dextroscoliosis group showed greater safe zone than nonscoliosis group (77.78% vs 74.40% at L2-3; p 5 0.02, 72.15% vs 69.87% at L3-4; p 5 0.03, and 58.45% vs 54.39%; p 5 0.01). CSA of the psoas muscle on the concave side was significantly higher than the convex side at L2-3 and L3-4 level (p 5 0.02 and 0.01, respectively). Through all levels, the psoas muscle on the concave side were significantly thicker (p 5 0.00 at all levels) and showed higher FI rate than the convex side (p 5 0.01 at L1-2 level, 0.00 at the rest of levels). CONCLUSIONS: The retroperitoneal vessels on the convex side is positioned more anteriorly while the ventral nerve roots did not show significant positional alterations. These changes lead to the increase of the safe zone on the convex side. The atrophy and thickness of the psoas muscle are other important factors and all things considered, the convex side seems to provide optimal access to the disc space and would lead to less injury of psoas muscle in performing LLIF for the patients with LDS. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs. http://dx.doi.org/10.1016/j.spinee.2015.07.179
Refer to onsite Annual Meeting presentations and postmeeting proceedings for possible referenced figures and tables. Authors are responsible for accurately reporting disclosures and FDA device/drug status at time of abstract submission.
157S
mortality were PVD, bleeding disorder and prior neuromuscular injury. Mortality was also associated with extending the fusion to the pelvis. These factors should be considered carefully during medical optimization and risk stratification. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
http://dx.doi.org/10.1016/j.spinee.2015.07.177
147. MRI-Based Determination of Convex or Concave Surgical Approach for Lateral Lumbar Interbody Fusion in Lumbar Degenerative Scoliosis Myung-Hoon Shin, MD; Seoul, South Korea
146. Biomechanical Assessment of L5 Nerve Root Strain in a 3D Print High-Grade Spondylolisthesis Model Keun Heng Huo, MD1, Alexander Peterson, BA2, S. Samuel Bederman, MD, PhD, FRCSC3, Lauren Nguyen4; 1University of California Irvine, Orange, CA, US; 2Marina Del Rey, CA, US; 3University of California Irvine Department of Orthopaedic Surgery, Orange, CA, US; 4Stanford, CA, US BACKGROUND CONTEXT: The surgical reduction of high-grade spondylolisthesis remains controversial given the potential for intraoperative nerve injury. Various reduction methods, including rotational and translational variants, have been described in the literature but no objective comparison study assessing the respective nerve strain exists in the current literature. PURPOSE: The purpose of our study was to compare the nerve strain of the L5 nerve root, for both a rotational and translational reduction maneuver. STUDY DESIGN/SETTING: A 3D printed lumbar spine and sacrum, rendered from the CT scan of a patient with grade 3 spondylolisthesis, was utilized. A custom testing jig situating the spine in the prone position to simulate intra-operative layout allowed for two reduction techniques: translation-dominant and rotation-dominant. Two starting positions (75% slip) were set at neutral (A1) and 15 of relative lordosis (A2). Two ending positions (0% slip) were set at neutral (B1) and 15 of relative kyphosis (B2). This allowed for four different reduction paths (A1-B1, A1-B2, A2-B1, A2-B2). PATIENT SAMPLE: The patient sample comprises a single patient with Grade 3 spondylolisthesis, whose CT scan was 3D printed for our model. Although only one patient’s spine was utilized, by incorporating variable aspects to approach the reduction, such as the reduction maneuver and different inclinations for the starting/ending points, the sample could be tested under multiple different scenarios to further expand the study’s clinical application. OUTCOME MEASURES: The primary outcome measure was nerve strain, calculated from the variable length of the nerve between the two points along the anatomic course of the L5 nerve root on the L5 vertebral body and the sacrum during reduction. METHODS: After mounting the 3D model onto the custom jig, a 3D motion-tracking device was used to measure the distance between two anatomic reference points used to represent L5 length during reduction from 75% to 0% slip. To ensure repeatability, two different investigators repeated all reductions 10 times each. Repeated-measures ANOVA and paired t-tests were used in statistical analysis. This methodology was applied for all four reduction paths in both the rotation-dominant and translational-dominant reductions. RESULTS: On average, across all paths, rotatory reduction produced 34.4% less L5 nerve strain than the translational reduction. The lordotic starting position led to 7.9% less nerve strain than neutral. The kyphotic ending position produced 15.1% more strain across all starting positions and reduction maneuvers. The A2-B1 path with rotatory reduction produced the least nerve strain. CONCLUSIONS: Based on this study, a rotation-dominant reduction with the patient in prone lordotic positioning may minimize L5 injury during surgical reduction of spondylolisthesis. Clinical studies are needed to confirm these findings.
http://dx.doi.org/10.1016/j.spinee.2015.07.178
BACKGROUND CONTEXT: The lateral lumbar interbody fusion (LLIF) is increasingly employed to treat lumbar degenerative scoliosis (LDS). Concerns remain about the transpsoas dissection-related complications. However, there is little information documenting which side is more appropriate for safety, the concave or the convex side. PURPOSE: The authors undertook this radiologic study to suggest the optimal approach side for LLIF by comparing the safe zone and psoas muscle on the concave and convex side of the patients with LDS. STUDY DESIGN/SETTING: Comparative MR image analysis. PATIENT SAMPLE: We retrospectively constructed cohort of the patient who had been diagnosed with LDS in out-patient clinic during the period from January 2012 to December 2013. The non-scoliosis group included 35 patients, the levoscoliosis group had 33 patients and the dextroscoliosis group had 35 patients. OUTCOME MEASURES: Ventral overlap is a distance between the anterior border of the vertebral body and the posterior border of the retroperitoneal vessels (aorta, common iliac artery, vena cava or common iliac vein depending on its level). Dorsal overlap is a distance between the posterior border of the vertebral body and the ventral edge of the nerve roots. Using these parameters, distance of the safe zone (a-(bþc)) at each level and percentage of safe zone to each vertebral body were calculated. Cross-sectional area (CSA), fatty infiltration (FI) rate and thickness of psoas muscle on both concave and convex side at each level was evaluated. METHODS: The differences between the two groups were assessed by means of the student’s t-test or Mann-Whitney U test according to the result of the Kolmogorov-Smirnov test. A p-value less than or equal to 0.05 was considered to indicate statistical significance. RESULTS: The ventral overlap on the convex side was decreased at L3-4 and L4-5 level in the levoscoliosis group (p 5 0.05 and 0.01, respectively) and at L2-3 and L3-4 level in the dextroscoliosis group (p 5 0.01 and 0.03, respectively) while the dorsal overlap showed no significant changes on both sides in both groups. In the levoscoliosis group, the convex side at L3-4 and L4-5 level presented greater safe zone than the nonscoliosis group (76.11% vs 74.00% at L3-4; p 5 0.02, 69.37% vs 63.16% at L45; p 5 0.00). Likely, the convex side at L2-3, L3-4 and L4-5 level in the dextroscoliosis group showed greater safe zone than nonscoliosis group (77.78% vs 74.40% at L2-3; p 5 0.02, 72.15% vs 69.87% at L3-4; p 5 0.03, and 58.45% vs 54.39%; p 5 0.01). CSA of the psoas muscle on the concave side was significantly higher than the convex side at L2-3 and L3-4 level (p 5 0.02 and 0.01, respectively). Through all levels, the psoas muscle on the concave side were significantly thicker (p 5 0.00 at all levels) and showed higher FI rate than the convex side (p 5 0.01 at L1-2 level, 0.00 at the rest of levels). CONCLUSIONS: The retroperitoneal vessels on the convex side is positioned more anteriorly while the ventral nerve roots did not show significant positional alterations. These changes lead to the increase of the safe zone on the convex side. The atrophy and thickness of the psoas muscle are other important factors and all things considered, the convex side seems to provide optimal access to the disc space and would lead to less injury of psoas muscle in performing LLIF for the patients with LDS. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs. http://dx.doi.org/10.1016/j.spinee.2015.07.179
Refer to onsite Annual Meeting presentations and postmeeting proceedings for possible referenced figures and tables. Authors are responsible for accurately reporting disclosures and FDA device/drug status at time of abstract submission.