UNILATERAL LUMBAR FUSION

Unilateral fusion of the lumbar spine is rarely necessary or indicated. However, in patients with a "far-out syndrome" requiring decompression or in cases where unilateral posterior element resection is necessary for any reason, it may be both necessary and indicated. This unilateral destabilization effectively removes one leg of the tripod, rendering that intervertebral joint potentially unstable. The charts and radiographs of 13 patients (seven men, six women) with an average age of 60 years (range, 25 to 76) who underwent unilateral fusion were retrospectively reviewed. Follow-up time ranged from 12 1/2 to 2 years with a median follow-up of 8 years. Eleven of the fusions were at one level, and two were at two levels. Seven patients had a far-out syndrome secondary to degenerative scoliosis; four were secondary to spondylolisthesis. Two patients had an osteoid osteoma involving a pedicle. A paraspinal approach was used in the majority of patients. Autologous bone graft was used in all patients. Unilateral pedicle screw fixation was used in the last patient in the series. The fusion rate was 85% (11/13). Three patients were smokers, two of whom developed pseudarthrosis. Disc space height did not appear to affect fusion rate. There was no progression of slip noted in any of the patients. One complication was noted in this group: a moderate postoperative infection, which cleared spontaneously.