Comparison of clinical and radiological outcomes after automated open lumbar discectomy and conventional microdiscectomy: a prospective randomized trial.

OBJECTIVE

Microdiscectomy (MD) is the gold standard for surgical discectomy. As a minimally invasive discectomy, automated open lumbar discectomy (AOLD) is designed to preserve annular integrity and disc height as well as effectively remove herniated disc and degenerated disc material. However, there have been no prospective clinical studies comparing their effectiveness. The study was designed to compare clinical and radiological outcomes after AOLD with those of MD.

METHODS

Seventy-eight patients were evaluated for unilateral leg pain with the presence of disc herniation on magnetic resonance imaging (MRI) scans at a single attributable level. Sixty-two patients were enrolled; 33 patients (53%) were randomly assigned to the AOLD group and the remaining 29 patients (47%) were assigned to the MD group. Follow-up assessment was performed for 19 of the AOLD patients and 17 of the MD patients. The average follow-up period was 20 months. Clinical and functional outcomes were assessed using VAS and ODI scores. Change of disc height (DH), instability, and disc degeneration were assessed from radiographs, while Modic change and reherniation were assessed using MRI scans.

RESULTS

Postoperative VAS scores for leg pain and ODI scores for function were significantly improved in both groups. Postoperative VAS for back pain tended to decrease in the MD group but the decrease was statistically insignificant (P = 0.081). The postoperative VAS for back pain was significantly reduced in the AOLD group (P = 0.012). Patients from the MD group showed greater DH reduction than the AOLD group (P = 0.049). The MD group experienced greater disc degeneration and Modic change than the AOLD group. Follow-up MRI revealed 2 cases of reherniation in the AOLD group; 1 case was symptomatic, the other was asymptomatic.

CONCLUSIONS

AOLD showed comparable clinical and radiological outcomes to conventional MD. AOLD preserves the central disc and removes only the loose degenerative disc fragments that are the main cause of reherniation by small annulotomy. Our results suggest that preservation of the central disc prevents loss of disc height and segmental instability, which is related to postdiscectomy back pain.