Incidence and risk factors of reoperation in patients with adjacent segment disease: A meta-analysis.

STUDY DESIGN: This was a systematic review of the literature and meta-analysis. OBJECTIVE: The objective of this study was to evaluate the current literature regarding the risk factors contributing to reoperation due to adjacent segment disease (ASD). SUMMARY OF BACKGROUND DATA: ASD is a broad term referring to a variety of complications which might require reoperation. Revision spine surgery is known to be associated with poor clinical outcomes and high rate of complications. Unplanned reoperation has been suggested as a quality marker for the hospitals. MATERIALS AND METHODS: An electronic search was conducted using PubMed. A total of 2467 articles were reviewed. Of these, 55 studies met our inclusion criteria and included an aggregate of 1940 patients. Data were collected pertaining to risk factors including age, sex, fusion length, lumbar lordosis, body mass index, pelvic incidence, sacral slope, pelvis tilt, initial pathology, type of fusion procedure, floating versus sacral or pelvic fusion, presence of preoperative facet or disc degeneration at the junctional segment, and sagittal orientation of the facets at the junctional segment. Analysis of the data was performed using Comprehensive Meta-Analysis software (Biostat, Inc.). RESULTS: The overall pooled incidence rate of reoperation due to ASD from all included studies was 0.08 (confidence interval: 0.065-0.098). Meta-regression analysis demonstrated no significant interaction between age and reoperation rate (P = 0.48). A comparison of the event rates between males and females demonstrated no significant difference between male and female reoperation rates (P = 0.58). There was a significantly higher rate of ASD in patients with longer fusion constructs (P = 0.0001). CONCLUSIONS: We found that 8% of patients in our included studies required reoperation due to ASD. Our analysis also revealed that longer fusion constructs correlated with a higher rate of subsequent revision surgery. Therefore, the surgeon should limit the number of fusion levels if possible to reduce the risk of future reoperation due to ASD. LEVEL OF EVIDENCE: IV.

Posterior Thoracolumbar Instrumented Fusion for Burst Fractures: A Meta-analysis.

STUDY DESIGN: This was a meta-analysis study. OBJECTIVE: To compare different posterior spine fixation methods for burst fracture fixation. SUMMARY OF BACKGROUND DATA: This study was performed to elucidate if the current body of literature supports one posterior spinal fusion fixation method for burst fracture to minimize the rate of implant failure and progression of posttraumatic kyphosis. MATERIALS AND METHODS: An extensive electronic search was conducted using PubMed for pertinent articles. The articles were examined against the inclusion and exclusion criteria. Data pertaining to kyphosis angle, Frankel score, vertebral level, blood loss, operation time, hospital stay, postoperative bracing, instrument failure, complications, and follow-up were collected. A random effects model was chosen due to variation among the individual studies' patient populations and surgical methods. RESULTS: A total of 23 publications were eventually deemed eligible according to the criteria and included into this study. The group with 2 levels above and 1 below with intermediate screws had the greatest maintenance of spine kyphosis and lowest implant failure at final follow-up (P<0.001). There was no difference between the periods of hospital stay (P=0.788) and blood loss (P=0.154) among different tiers. CONCLUSIONS: A fixation method consisting of 2 levels above and 1 below with intermediate screws for the thoracolumbar burst fractures showed the highest correction of kyphosis angle both at immediate and final follow-up and also the lowest implant failure at final follow-up.

Safe zone for irrigation and debridement of psoas abscess through a dorsal spinal approach.

PURPOSE: This cadaver study was initiated to identify safe zones for psoas abscess debridement using a dorsal spinal approach. METHODS: Twenty total specimens were dissected and lumbar transverse process (TP) and psoas muscles were identified. The distance from the lateral psoas muscle to the transverse process tip was measured. The lumbar plexus was dissected from the psoas and the distance from the TP to the lateral border of the lumbar plexus was measured. The area between the lateral edge of the psoas and lumbar plexus at each lumbar level was considered a safe zone of approach for entry into the psoas muscle for abscess debridement. RESULTS: The most lateral portion of the lumbar plexus was 9.3 mm medial to the superior tip of the L1 TP and 9.2 mm medial to the inferior tip at L1, it was 11.8 and 11.7 mm medial at L2, 10.5 and 9.8 mm medial at L3, 6.6 and 6.2 mm medial at L4, and 1.0 and 0.9 mm medial at L5. The distances from the TP tip to the lateral edge of the psoas muscle were 5.7 and 5.5 mm medial to the superior and inferior tip of the TP at L1, 5.1 and 4.7 mm medial at L2, 2.5 and 1.8 mm medial at L3, 0.4 and 0 mm medial at L4 and 3.7 and 3.8 mm lateral at L5. CONCLUSIONS: This study provides landmarks to avoid the critical structures in the lumbar spine.

Posterior identification and exposure of the V3 segment of the vertebral artery.

OBJECTIVE: The purpose of this study was to define the anatomy of the V3 segment of the vertebral artery (VA) from the posterior approach. METHODS: Ten formalin-fixed cadavers were carefully dissected bilaterally using landmark features to identify and safely expose the VA from the posterior. Measurements regarding morphometric characteristics of landmark features and feasible resection quantifications were obtained and analyzed. The C2 pars was resected completely in all cadavers, averaging 15.03 ± 1.06 mm in thickness. RESULTS: The average diameter of the VA at the midline of C2 on the right side was 4.66 ± 0.51 mm compared to the left 5.2 ± 0.49 mm (P = 0.002). The distance of the VA from the midline increased from caudal to rostral. The distance between the VA to the lateral edge of the dura in the middle of the window of approach was 9.67 ± 0.81 mm. The rostral-caudal length of the window of approach was 21.94 ± 1.60 mm. The percentage of C2 body removal was 28.04% ± 6.09% through each side (249.55 ± 55.5/898.2 ± 146.17 mm2). While carefully exposing the VA, a posterior approach can be feasible in cases of injury during C1-C2 instrumentation or during resection of tumors of the C2 pars with or without extension into the C2 body. DISCUSSION: The posterior approach for a C2 partial corpectomy can also be used as an adjunct to anterior approaches when necessary to widen the extent of bone resection. CONCLUSION: Exposure of the V3 segment of the vertebral artery was defined as well as the extent of C2 corpectomy through the posterior approach.