Learning curve of full-endoscopic lumbar discectomy

Abstract

Purpose: To report the learning curve of full-endoscopic lumbar discectomy for a surgeon naive to endoscopic surgery but trained in open microdiscectomy.

Methods: From July 2006 to July 2009, 57 patients underwent full-endoscopic lumbar discectomy and 66 underwent open microdiscectomy. The clinical results were evaluated with a visual analog scale (VAS) and the Oswestry Disability Index (ODI). Spearman's coefficient of rank correlation (rho) was used to assess the learning curves for the transforaminal and interlaminar procedures of full-endoscopic lumbar discectomy.

Results: After full-endoscopic lumbar discectomy, the VAS and ODI results of the patients followed up were comparable with those of open microdiscectomy. A steep learning curve was observed for the transforaminal procedure, but not the interlaminar procedure.

Conclusions: The learning curve of the transforaminal approach was steep and easy to learn, while the learning curve of the interlaminar approach was flat and hard to master.

Figures

Fig. 1

a Lateral approach for the full-endoscopic transforaminal operation. Patient is placed in the prone position under a fluoroscope (triangle). The midline and cranial side are indicated by a dashed line and a star, respectively. b Intraoperative anteroposterior fluoroscopic image of the transforaminal operation with working sheath (short arrow) and Kerrison punch (long arrow). c Intraoperative view in transforaminal approach with the traversing nerve (short arrow), and margin of the disc space (stars)

Fig. 2

a Interlaminar approach for the full-endoscopic operation. Cranial side is indicated by a star. b A nerve root (star) is seen before being pushed away by a working sheath (long arrow). c A disc (triangle) is disclosed partially when the nerve root (star) is pushed away by the working sheath (long arrow). d A pin (short arrow) penetrating the annulus fibrosus of the disc (triangle) with the nerve root (star) protected and mobilized by rotating the working sheath (long arrow). e Only the disc (star) with the pin (short arrow) is seen in the operative field, while the nerve is fenced by the working sheath (long arrows). f Intraoperative lateral fluoroscopic image of the interlaminar operation with working sheath (short arrow) and Kerrison punch (long arrow). g Intraoperative view in interlaminar access with the ligamentum flavum (triangles), the traversing nerve (long arrow), and margin of the disc space (stars)

Fig. 3

Flow chart summarizing surgical options and results of full-endoscopic lumbar discectomy

Fig. 4

Operation time plotted against time interval between 33 cases of full-endoscopic transforaminal discectomies attempted