Learning Curve for Minimally Invasive Spine Surgeries: A Review of Initial 162 Patients in Five Years of Implementing MISS Technique

Abstract

Objective An inherent learning curve is associated with minimal invasive spine surgery (MISS). Operation time, complications and learning-curve are associated with one another during an initial learning. The purpose was to identify the learning-curve in MISS procedures (for both discectomy and fixations). Methods We performed a retrospective analysis in initial 162 patients who were operated by a single surgeon during first five-years of independently implementing MISS. All surgeries were performed using tubular retractor between 2012 and 2016 in form of microendoscopic discectomy (MED), and later added with MISS-fixations. All had single or double level disc herniation with or without lumbar stenosis and/or instability. In-patient charts were reviewed to compare intraoperative blood loss, operative time, hospital stay and complications. Results Average age was 44.4±12.2 years and average operation time was 113.5±61.9 minutes. Operative time was decreased to less than 90 minutes after 30 surgeries, and less than 60 minutes after 50 surgeries for MED. For MISS-fixations, it was 191.8±33.8 minutes. Average hospital stay was 3.1±1.4 days, which was significantly less in MED compared to MISS-fixation (p<0.0001). Preoperative VAS was improved from 8.6±0.9 to 1.9±1.2 (p<0.05) postoperatively. Preoperative ODI was improved from 62±6.8 to 17.9±5.8 postoperatively. Complication rate was 13.6% (n=22) and revision surgery rate was 6.2% (n=10). Intraoperative and postoperative complications such as, dural tear, root sleeve injury, postoperative hematoma, incomplete excision requiring revision and loosening of screw cap were found during initial fifty surgeries; however, recurrent disc and iatrogenic instability was found throughout the series. Conclusion Fellowship training facilitates art of learning MISS surgeries and infuse confidence during initial 30 surgeries. Higher complications and operative time is commonly encountered during learning curve. Surgeon needs to stay persistent despite initial complications. After 50 cases, a plateau is usually attained with less complications and satisfactory outcome.

Keywords

• complications
• learning curve
• minimally invasive spine surgery
• young surgeons