Learning curve for full-endoscopic lumbar decompression via interlaminar approach using the learning curve cumulative summation analysis.

Abstract

Full-endoscopic spine surgery (FESS) is generally considered to have a steep learning curve due to its technical complexity. This study aimed to evaluate the learning curve for full-endoscopic decompressive laminectomy via the interlaminar approach using learning curve cumulative summation test (LC-CUSUM) analysis, which provides objective statistical monitoring of surgical competency acquisition, and determine the number of cases required for surgical competency. We retrospectively analyzed the first 60 consecutive patients who underwent single-level interlaminar endoscopic unilateral lumbar decompression for lumbar spinal stenosis performed by a single surgeon with 4 years of experience. LC-CUSUM analysis was employed with operative time as the primary outcome measure. The target time was set at 80 min, based on the same surgeon's mean operative time for microscopic laminectomy. The patients were divided into the early (≤ 30 cases) and late (> 30 cases) learning periods and compared. LC-CUSUM analysis revealed that competency was achieved after 51 cases. The mean operative time significantly decreased from 90.20 ± 24.44 min in the early period to 71.47 ± 16.65 min in the late period (p = 0.001). Estimated blood loss showed significant reduction (54.83 ± 42.58 ml vs. 34.83 ± 19.10 ml, p = 0.024). Complication rates remained consistent between periods (10% each), with similar rates of dural tears (6.67% in both periods). The results of this study have demonstrated that a learning period of 51 cases could be required to achieve proficiency in full-endoscopic interlaminar lumbar decompression. However, the procedure can be safely performed even during the early learning period by surgeons with adequate microscopic surgical experience.