Learning curve of tubular micro-endoscopic decompression in patients with degenerative lumbar canal stenosis over 200 cases

Abstract

Introduction: Tubular micro-endoscopic decompression is a technically demanding surgical technique involving familiarity of microscope handling with surgical and radiographic anatomical planning. Understanding the learning curve is necessary to delineate the problems faced during initial cases to reduce the complication rates and set guidelines for safe spine surgery through educational and training programs on bone-saw models and organizing workshops to enhance the standard of health care with improvement in surgical skills. Aims and Objectives: The aim of this study was to evaluate the learning curve of tubular micro-endoscopic decompression in patients with degenerative lumbar canal stenosis based on surgical and clinical parameters and delineate the challenges faced in early cases in long series of patients. Materials and Methods: Study design. Retrospective analysis of prospectively collected data. Study cohort. Data of first 220 consecutive patients with single-level degenerative lumbar canal stenosis managed with tubular micro-endoscopic decompression surgery from 2010 to 2016 with a minimum two-year follow-up were retrieved. Methodology. First 200 patients available at the final follow-up were divided into quartiles (50 each) as per the date of surgery with each consecutive group serving control for prior. Preoperatively and postoperatively clinical parameters (pain scores: visual analog scale [VAS]; functional disability: oswestry disability index [ODI] score), perioperative (operative time, blood loss, and hospital stay), technical issues (guide wire migration, tube docking-related problems, and dural tear), and postoperative complications (postoperative leg pain, neural injury, infection, and recurrence) were evaluated. Statistical analysis. The logarithmic curve-fit regression analysis and analysis of variance test were used to find the asymptote. Results: The mean age of patients was 61.81 years (ranging from 39 to 85) with male-to-female ratio of 121:79 with no significant difference among the quartiles. Statistically significant differences (P < 0.005) were noted in mean operative time (q1 = 109 min, q2 = 69.4 min) and mean blood loss (q1 = 110.6 mL, q2 = 69.6 mL) between the first and second quartiles with no further significant reduction in the third and fourth quartiles.Statistically significant differences (P < 0.005) in clinical parameters (VAS preoperative/postoperative 6.7/1.43; ODI preoperative/postoperative 39.08/12.63) were noted but were not associated with surgical experience. Hospital stay time did not show any significant difference among the quartiles.Guide wire-migrated issues, neural injury, dural tear, and tube docking-related problems significantly reduced after q1. However, recurrence occurred at any phase. Infection occurred in one patient in the first quartile.Although blood loss and operative time showed a declining trend, it was not significant after the second quartile. Therefore, asymptote lay in the first quartile; however, we recommend that novice surgeon should perform 50–100 cases to achieve mastery in this technique as different surgeons have different learning abilities. Conclusion: For mastering the art of tubular micro-endoscopic decompression for lumbar canal stenosis and to reduce its learning curve, novice surgeons can avoid the challenges and problems faced during initial cases with improvement in surgical skills by doing practice on cadavers and bone-saw models following certain recommendations that we came through our learning curve of surgical experience so that the results of their initial surgery are similar to the results that we had after achieving asymptote. Familiarity with instrumentation, communication between surgical team, and defined expectations from radiology technician are the keys to reduce the learning curve.

Keywords

• lumbar canal stenosis
• micro-endoscopic decompression
• operative time