Limited microdiscectomy for lumbar disk herniation: a retrospective long-term outcome analysis

Surgical treatment of lumbar disk herniation is traditionally accomplished by removal of the extruded fragment as well as an aggressive decompression of the disk space. This retrospective study evaluates the long-term results of limited discectomy, otherwise known as fragmentectomy, for lumbar disk herniation using a minimally invasive technique. Although there are ample studies in literature regarding short-term outcome after limited microdiscectomy, there is a paucity of literature for long-term outcomes after fragmentectomy. We present long-term outcomes averaging 7 years after limited discectomy.

A total of 152 patients were operated on between January 1, 2001 and June 30, 2003 for single-level herniated lumbar disks. All patients had microsurgical fragmentectomy performed through a small skin incision off the midline using a tubeless retraction system. Fifty-four patients participated in the study, whereas 98 patients were lost to long-term follow-up. Long-term outcome was assessed by telephone survey or mail-in survey using the Oswestry Low Back Pain Disability Index and a patient outcome survey. After Institutional Review Board approval and patient consent, all 54 patients had a thorough chart review for evaluation of further lumbar surgeries. The mean long-term follow-up was 86.2 months (range, 72-104 mo) or about 7.2 years.

Forty-eight of the 54 patients (88.9%) reported an excellent (26 patients) or good (22 patients) long-term outcome with surgery. Long-term back and leg pain improvement was seen in 44 of 49 (89.8%) and 44 of 50 (88.0%) patients reporting back or leg pain, respectively. The mean Oswestry Disability Index for long-term follow-up was 8.89, indicating minimal disability. Same-level recurrences requiring reoperation were seen in 6 of the 54 patients who participated (11.1%) within the average 86.2-month follow-up. Four of 34 (11.85%) known contained herniations and 2 of 20 (10.0%) known extruded herniations presented for same-level surgical recurrence. All recurrences were successfully treated with reexploration and fragmentectomy. Two patients from the recurrence group and 1 from the original 54 progressed to need an arthrodesis at the initial operated level (5.6%). One patient in the same-level recurrence group and 2 patients from the original 54 developed an operative herniated disk at an adjacent level (5.6%).

Our long-term outcome study shows that a minimally invasive approach to microdiscectomy with removal of the fragment only is an effective way to treat lumbar disk herniation. The rate of recurrence in our long-term study seems slightly higher compared with previously published studies, which generally had shorter follow-up periods. Long-term patient outcomes for back and leg pain were also very low. No appreciable difference in operative reherniation could be found with patients who had contained verses extruded fragments. It is difficult to predict from this study whether a simple fragmentectomy was the cause of the progression to further surgeries or whether this was the natural progression of a degenerative spine. Further prospective trials are necessary to fully understand the factors associated with limited microdiscectomy.