BACKGROUNDIn recent years, a variety of minimally invasive lumbar surgery techniques have achieved desirable efficacy, but some dispute remains regarding the advantages over open surgery. This study aimed to compare minimally invasive lumbar interbody fusion via MAST Quadrant retractor with open surgery in terms of perioperative factors, postoperative back muscle function, and 24-month postoperative follow-up results.

METHODSFrom September 2006 to June 2008, patients with single-level degenerative lumbar spine disease who were not responsive to conservative treatment were enrolled in this study. Patients were randomized to undergo either minimally invasive surgery (MIS, transforaminal lumbar interbody fusion via MAST Quadrant retractor, 41 cases) or open surgery (improved transforaminal lumbar interbody fusion, 38 cases).

RESULTSThe MIS group had longer intraoperative fluoroscopy time than the open surgery group, and the open surgery group had significantly increased postoperative drainage volume and significantly prolonged postoperative recovery time compared with the MIS group (P < 0.05 for all). MRI scanning showed that the T2 relaxation time in the multifidus muscle was significantly shorter in the MIS group than in the open surgery group at 3 months after surgery (P < 0.01). Surface electromyography of the sacrospinalis muscle showed that the average discharge amplitude and frequency were significantly higher in the MIS group than in the open surgery group (P < 0.01). The Oswestry disability index and visual analog scale scores were better at 3, 6, 12 and 24 months postoperatively than preoperatively in both groups. Both groups of patients met the imaging convergence criteria at the last follow-up.

CONCLUSIONSMIS can effectively reduce sacrospinalis muscle injury compared with open surgery, which is conducive to early functional recovery. In the short term, MIS is superior to open surgery, but in the long term there is no significant difference between the two procedures.