MATERIAL and METHODS: Preoperative and postoperative 3rd and 6th month MRI features, visual analog scale (VAS), and Oswestry Disability Index (ODI) scores, as well as other clinical features of patients who underwent monoportal endoscopic lumbar discectomy between August 2009 and January 2012 were retrospectively analyzed.

RESULTS: A total of 65 patients (37 female, 28 male) were included in the study. VAS and ODI scores showed significant improvement postoperatively (p<0.001). Intervertebral disc height loss was observed only in two patients. In 31 (48%) of the 64 levels treated, no significant anterior soft tissue mass developed. However, 33 patients (52%) showed anterior epidural edema and tissue formation postoperatively. Contrast enhancement of the nerve root was found in 20 levels (29.4%), nerve root edema in 3 levels (4.41%), and nerve root displacement in 3 levels (4.41%). None of the patients had all 3 aforementioned findings concomitantly. Of the 57 levels evaluated, 36 levels (63%) showed no or minimal changes in the posterior elements, and at the 3rd month, 9 levels (15.8%) demonstrated grade 1+ changes, 9 levels showed grade 2+ changes, and grade 3+ changes were seen in only 3 levels; however, at 6-month follow-up, all vertebral levels showed improvements.

CONCLUSION: Endoscopic discectomy is a safe and effective minimally-invasive method. However, owing to the lack of definitive radiological criteria indicating success or failure, the radiological findings should always be interpreted in conjunction with clinical outcomes. Keywords : Lumbar disc herniation, Endoscopic lumbar discectomy, Interlaminar discectomy, Transforaminal discectomy, Postoperative magnetic resonance imaging, Outcome