Endoscopic Transforaminal Suprapedicular Approach in High Grade Inferior Migrated Lumbar Disc Herniation

Objective : Although endoscopic procedures for lumbar disc diseases have improved greatly, the postoperative outcomes for high grade inferior migrated discs are not satisfactory. Because of anatomic limitations, a rigid endoscope cannot reach all lesions effectively. The purpose of this study was to determine the feasibility of endoscopic transforaminal suprapedicular approach to high grade inferior-migrated lumbar disc herniations. Methods : Between May 2006 and March 2008, a suprapedicular approach was performed in 53 patients with high grade inferior-migrated lumbar disc herniations using a rigid endoscope and a semi-rigid flexible curved probe. One-to-four hours after surgery, the presence of remnant discs was checked with MRI. The outcomes were evaluated with the visual analogue scale (VAS) score and the Oswestry Disability Index (ODI) one week after surgery. Results : The L2-3 level was involved in 2 patients and the L3-4 level was involved in 14 patients, while the L4-5 level was involved in 39 patients. There were single piece-type in 34 cases and a multiple piece-type in 19 cases. Satisfactory results were obtained in all cases. The mean preoperative VAS for leg pain was $9.32{\pm}0.43$ points (range, 7-10 points), whereas the mean ODI was $79.82{\pm}4.53$ points (range, 68-92 points). At the last follow-up examination, the mean postoperative VAS for leg pain was $1.78{\pm}0.71$ points and the mean postoperative ODI improved to $15.27{\pm}3.82$ points. Conclusion : A high grade inferior migrated lumbar disc is difficult to remove sufficiently by posterolateral endoscopic lumbar dscectomy using a rigid endoscope. However, a satisfactory result can be obtained by applying a transforaminal suprapedicular approach with a flexible semi-rigid curved probe.