Learning curve of percutaneous endoscopic interlaminar lumbar discectomy versus open lumbar microdiscectomy at the L5-S1 level

Abstract

OBJECTIVE: Many studies on the clinical outcome of full endoscopic spine surgery versus open spine surgery have been published. However, only a few studies have compared the learning curves of percutaneous endoscopic interlaminar lumbar discectomy (PEILD) and open lumbar microdiscectomy (OLM) at the L5-S1 level. This study included patients with disc herniation at the L5-S1 level, who underwent PEILD or OLM performed by a single novice surgeon and compared the learning curves. METHODS: Fifty-six patients who underwent PEILD or OLM at the L5-S1 level and completed a minimum 1-year follow-up were enrolled in the study. The patients were allocated to the PEILD group (n = 27, September 2014 to August 2016) or an OLM group (n = 29, September 2012 to August 2014). The learning curves were retrospectively compared based on operation time and surgical outcomes, including complication, failure, and recurrence rates were retrospectively compared. RESULTS: Significant intergroup differences were not noted with respect to the baseline characteristics, including age, sex, body mass index, preoperative symptoms, or preoperative radiological findings. The mean operation time was significantly shorter in the PEILD group than in the OLM group (63.89±17.99 min versus 78.03±19.01 min, p = 0.006). Based on the operation time according to the number of cases, the learning curve was more difficult in the PEILD group according to the cumulative analysis (case number cut-off for proficiency was 18 in the PEILD group versus 10 in the OLM group) and linear regression analysis (proportionality constant for decrease in the operation time was -0.922 in the PEILD group versus -1.738 in the OLM group) than that in the OLM group. However, the surgical outcomes, including failure, surgical efficacy based on nerve root decompression, complication, and recurrence rates did not differ between the two groups. CONCLUSION: Although the learning curve of PEILD was more difficult than that of OLM, the mean operation time was shorter in the PEILD group than that in the OLM group. Moreover, based on the surgical outcomes, PEILD showed efficacy and safety similar to those of OLM.