41. Surgical outcomes for upper lumbar disc herniations: a systematic review and meta-analysis of the literature

Abstract

BACKGROUND CONTEXT Upper lumbar disc herniations (ULDH) represent approximately 10% of lumbar disc herniations and are known to have distinct clinical presentations from lower lumbar disc herniations (LLDH), yet surgical outcomes are not well understood. PURPOSE To review the surgical outcomes of discectomy for ULDH, compare standard open laminectomy and microdiscectomy (OLM) vs minimally invasive surgical (MIS) techniques, and compare results of disc herniations at L1-3 v. L3-4. STUDY DESIGN/SETTING A systematic review of articles reporting outcomes of nonfusion surgical treatment of L1-2, L2-3, and/or L3-4 disc herniations was performed. Abstracts were identified through a search of the PubMed/Medline database along with a review of bibliographies of examined articles. The inclusion and exclusion of studies was performed according to the latest version of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Statement. PATIENT SAMPLE Fourteen studies encompassing 773 patients reported outcomes of conventional OLM. Nine case series on minimally invasive approaches to ULDH collected described total of 4 techniques: percutaneous endoscopic lumbar discectomy (PELD), oblique paraspinal (OP), tubular microdiscectomy (TM), and lateral retroperitoneal approach (LRA). PELD was the most reported with 4 studies that describe experience for a total of 126 patients. OUTCOME MEASURES Studies were divided into conventional OLM or MIS technique. Average age of patients, follow-up duration, and gender were recorded. Reported outcomes were collected and divided into groups by level as provided. Outcome measures varied greatly, and in order to perform a combined analysis, outcomes were reassigned into either satisfactory or unsatisfactory. Factors such as length of surgery, blood loss, and hospital length of stay were largely undescribed and thus not available for analysis. METHODS Two methods were used for the meta-analysis and forest plots: the classical inverse variance method, which yields weight for each study, and the Generalized Linear Mixed Model (GLMM) method. Fixed effects model was used and the pooled proportion was computed using the R package, meta, using the statistical computing software R. For comparisons, GLMM was used to compare using the SAS procedure, GLIMMIX. Statistical significance level was set as p RESULTS A total of 23 articles were included in the analysis (14 OLM and 9 MIS techniques). A range of 58% to 92% of patients reported favorable outcomes for all L1-4 disc levels. There was no significant improvement with MIS techniques compared with standard OLM, OR=0.86, 95% CI: (0.42, 1.74), p=0.66. Among MIS techniques outcomes of PELD vs OLM yielded a slight trend toward significance favoring OLM with an OR=0.50, 95% CI: (0.21, 1.16), and p= 0.10. OP and TM were not significantly different from OLM regarding the outcome of satisfactions with the surgery, OP vs OLM: OR=1.04, 95% CI: (0.20, 5.25), p=0.96, and TM vs OLM: OR=2.15, 95% CI: (0.38, 12.38), p=0.36. Comparisons for LRA could not fit the maximum likelihood model as all surgeries were reported as 100% satisfactory. Separating results by levels a trend toward significance of higher satisfaction with L3-4 vs L1-3 with standard OLM surgery, OR=0.46, 95% CI: (0.19, 1.12), p=0.08. CONCLUSIONS Our analysis supports that ULDH have an overall success rate of approximately 80%, but has not improved with MIS techniques. Discectomy for herniations at L3-4 trends toward better outcomes compared with disc herniations at L1-2 and L2-3, but was not significant. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.