Preoperative ODI and Intake of Analgesics Predict Outcome after Lumbar Microdiskectomy: Results from a Prospective Register.

BACKGROUND: Lumbar disk herniation (LDH) typically causes leg pain and neurologic deficits, but can also be a source of low back pain (LBP). Lumbar microdiskectomy (LMD) is among the most common neurosurgical procedures to relieve radicular symptoms. It is important for both surgeon and patient to understand potential predictors of outcome after LMD. The aim of this study was to investigate if the presence and intensity of preoperative LBP, the ODI score, and analgesic intake can predict the outcome of patients undergoing LMD. METHODS: This is a single-center retrospective study based on the analysis of prospectively acquired data of patients in the SwissDisc Registry. A total of 685 surgeries on 640 patients who underwent standardized LMD at our institution to treat LDH were included in this study. We performed multivariable linear regression analysis to determine preoperative predictors for patient outcomes based on the Oswestry Disability Index (ODI) scores, recorded on average 39.77 (±33.77) days after surgery. RESULTS: Our study confirmed that surgery overall improves patient degree of disability as measured by ODI score. Following model selection using Aikake Information Criterion (AIC), we observed that higher preoperative ODI scores (ß: 0.020 [95% CI: 0.008 to 0.031]) and higher number of analgesic medication usage by patients prior to surgery (ß: 0.236 [95% CI: 0.057 to 0.415]) were both associated with an increased postoperative ODI score. CONCLUSION: LDH surgery generally improves patient degree of disability. The analysis of patients with a high preoperative ODI score and increased intake of analgesics before surgery predicted a worsening of patients' disability after LMD in this subgroup.

Incidence and clinical impact of vertebral endplate changes after limited lumbar microdiscectomy and implantation of a bone-anchored annular closure device.

BACKGROUND: An annular closure device (ACD) could potentially prevent recurrent herniation by blocking larger annular defects after limited microdiscectomy (LMD). The purpose of this study was to analyze the incidence of endplate changes (EPC) and outcome after LMD with additional implantation of an ACD to prevent reherniation. METHODS: This analysis includes data from a) RCT study-arm of patients undergoing LMD with ACD implantation and b) additional patients undergoing ACD implantation at our institution. Clinical findings (VAS, ODI), radiological outcome (reherniation, implant integrity, volume of EPC) and risk factors for EPC were assessed. RESULTS: Seventy-two patients (37 men, 47 ± 11.63yo) underwent LMD and ACD implantation between 2013-2016. A total of 71 (99%) patients presented with some degree of EPC during the follow-up period (14.67 ± 4.77 months). In the multivariate regression analysis, localization of the anchor was the only significant predictor of EPC (p = 0.038). The largest EPC measured 4.2 cm3. Reherniation was documented in 17 (24%) patients (symptomatic: n = 10; asymptomatic: n = 7). Six (8.3%) patients with symptomatic reherniation underwent rediscectomy. Implant failure was documented in 19 (26.4%) patients including anchor head breakage (n = 1, 1.3%), dislocation of the whole device (n = 5, 6.9%), and mesh dislocation into the spinal canal (n = 13, 18%). Mesh subsidence within the EPC was documented in 15 (20.8%) patients. Seven (9.7%) patients underwent explantation of the entire, or parts of the device. CONCLUSION: Clinical improvement after LMD and ACD implantation was proven in our study. High incidence and volume of EPC did not correlate with clinical outcome. The ACD might prevent disc reherniation despite implant failure rates. Mechanical friction of the polymer mesh with the endplate is most likely the cause of EPC after ACD.