Clinical follow up after instrumentation-augmented lumbar spinal surgery in patients with unsatisfactory outcomes.

Abstract

The authors investigated the causes of unsatisfactory outcomes in patients who had undergone instrumentation-assisted lumbar surgery and followed the clinical and imaging results of the revision surgery. Myelography and postmyelography computed tomography (CT) scanning were successfully conducted in 103 patients. In nearly 80% of these patients, the main symptom was back pain, with or without leg pain. Additional electromyography and nerve conduction velocity studies were also conducted in 22 patients in whom CT myelography could not help to establish the definitive cause of surgical failure. There were 26 cases of spinal stenosis, 13 of adjacent-segment instability, 15 of pseudarthrosis, 11 of screw misplacement, four of epidural fibrosis, five of arachnoiditis, seven of disc disruption, and 22 miscellaneous. When conservative treatment failed to relieve symptoms, surgery was suggested whenever an operable lesion was found. Revision surgery was performed in 48 patients, and these cases form the basis of this retrospective cohort study. All patients underwent clinical and imaging follow up for a minimum of 2 years. Two-year clinical outcomes were assessed using the 36-Item Short Form Health Survey questionnaire and compared with earlier scores using the Student t-test. Fusion status was evaluated by two orthopedic surgeons, who examined flexion-extension x-ray films or CT studies. The greatest improvement after revision surgery was documented in patients with symptoms related to spinal stenosis or disc disruption. Little improvement was observed in patients with misplaced pedicle screws causing nerve injury and those with epidural fibrosis or arachnoiditis. Adequate decompression at the initial operation and prevention of restenosis or accelerated adjacent-segment degeneration yielded the most favorable prognosis in the present cases. Successful posterolateral arthrodesis combined with supplemental interbody fusion improved the surgical outcomes in cases involving disc disruption or degeneration.