[Instrumented slip reduction combined with 360 degrees circumferential fusion and restoration of laminae for adult isthmic spondylolisthesis].

OBJECTIVE

To evaluate the mid-term clinical outcome of instrumented slip reduction combined with 360 degrees circumferential fusion and restoration laminae for symptomatic adult isthmic spondylolisthesis.

METHODS

Between October 2004 and March 2008, 44 patients with symptomatic isthmic spondylolisthesis underwent instrumented slip reduction combined with 360 degrees circumferential fusion and restoration laminae. There were 15 males and 29 females with an average age of 38.4 years (range, 28-45 years). The disease duration was 14 months to 7 years (38 months on average). The affected vertebrae was L4-5 in 18 patients and L5, S1 in 26 patients. According to Meyerding's grade for spondylolisthesis, 28 cases were rated as grade II and 16 as grade III. The visual analogue scale (VAS), Oswestry disability index (ODI), and the short form 36 health survey (SF-36) scores were evaluated before operation and at last follow-up; the radiographical outcome was evaluated by measuring slipping percentage, heights of intervertebral space and foramen, and fusion rate. RESULTS; All patients were followed up 20-60 months (42 months on average). The VAS, ODI, and SF-36 scores were all significantly improved at last follow-up when compared with those before operation (P < 0.05). According to Morelos criteria, the clinical results were excellent in 32 patients, good in 9, and fair in 3; the excellent and good rate was 93.2%. The preoperative average percentage of slip was 47.5%, which was improved to 2.6% 3 days after operation; the total average reduction rate was 97.4%, and it was maintained at last followup. The heights of intervertebral space and foramen were all improved significantly after operation (P < 0.05), and there was no significant difference between at 3 days after operation and at last follow-up (P > 0.05). X-ray and CT showed bony fusion 1 year after operation in all patients with a fusion rate of 100%. Complications included pain at donor site of iliac bone in 4 cases, superficial infection in 2 cases, dural tear in 1 case, and degeneration of adjacent vertebrae in 2 cases; no nerve root injury, pseudoarthrosis, failure of internal fixation, and acquired spinal canal stenosis occurred. CONCLUSION; Instrumented slip reduction combined with 360 degrees circumferential fusion and restoration laminae is a reliable procedure for adult isthmic spondylolisthesis with satisfactory mid-term results, a high fusion rate and low complication rate. The long-term outcomes should be verified by follow-up in the future.