OBJECTIVESTo assess surgical treatment of lumbar spinal stenosis associated with unstable degenerative spondylolisthesis.

METHODSIn 86 patients with lumbar spinal stenosis associated with unstable degenerative spondylolisthesis. (30 men and 56 women, aged from 30 to 77 years), 63 patients complained of lower back pain with both lower extremity pain, 10 patients pain in one leg, and 13 patients only lower back pain. Seventy-two of these patients complained of intermittent claudication, with a walking distance ranging from 10 to 1 000 m. Thirty-two patients had some changes in sensation, motion and reflexes of the foot. According to White' critera, all patients showed dynamic instability of the lesion. Meyerding criteria showed degree 1 in 79 patients, and degree 2 in 7. CT scan was made in 56 patients, MRI in 24 and MRM in 6 before operation. Myelography was performed in 61 patients, and CTM in 6. Stenosis and spondylolisthesis located between L(4) and L(5) in 49 patients, between L(3) and L(4) in 6, between L(5) and S(1) in 25, between L(3) and L(4) and between L(4) and L(5) in 2, and from L(3) to S(1) in 4. The patients with pathological spondylolisthesis were excluded. Lateral recess stenosis of one leg was observed in 10 patients, lateral recess of both legs in 22, and central canal stenosis in 54, of whom 12 patients were associated with protrusion of the lumbar disc. Decompression and autograft with iliac bone and various internal fixation were performed in all patients.

RESULTSThe patients were followed up from 8 months to 13 years, longer than 1 year (average 5.6 years) in 81 patients. According to Amundsen et al, excellent results were obtained in 78 patients, good in 5, and fair in 3. Spondylolisthesis was completely reduced in 70 patients of degree 1 (89.9%), and in 6 patients of degree 2 (85.7%). No patient showed slippage aggravated. 74 patients gained bone graft fusion within 3 months and 10 patients within 6 months. Two patients showed pseudoarthrosis during the follow-up. Complications included internal fixation breakage in 1 patient, and delayed infection in 1.

CONCLUSIONSComplete decompression and bone graft fusion are the key to treatment. Decompression and internal fixation improve the symptoms of patients with lumbar spinal stenosis associated with spondylolisthesis. Transpedicle instrumentation can reduce spondylolisthesis and maintain the physical curve of the lumbar.