The learning curve of minimally-invasive lumbar microdiscectomy

Object: The safe integration into practice of a new surgical technique requires an appreciation of the learning curve. The object of this study was to assess the learning curve for minimally invasive microdiscectomy (MIM) utilizing a tubular retractor system. Methods: A prospective evaluation of a single surgeon's first 52 consecutive MIM cases for radiculopathy secondary to single-level posterolateral lumbar disc herniation was performed. The learning curve was assessed using operative time, conversion to open rate, complications, and length of hospitalization. Results: The duration of operative time decreased over the course of the study (range, 49-151 min). By case 15, operative time was typically 60 min or less. There was only one conversion to an open procedure (Case 2). Complications occurred in three cases. All but nine patients were discharged home on the day of surgery. Conclusion: The learning curve for MIM was demonstrated. Further assessment of this curve for a large group of surgeons is necessary before a randomized controlled trial comparing standard microdiscectomy to MIM can be conducted.