THE EFFECT OF INTERPOSITION MEMBRANE ON THE OUTCOME OF LUMBAR LAMINECTOMY AND DISKECTOMY

Study Design. This study evaluated clinical and magnetic resonance imaging differences of patients treated surgically for lumbar disc herniation. Clinical follow-up and magnetic resonance imaging evaluation of epidural fibrosis were used to assess patient outcome. Objectives, The purpose of this study was to evaluate the difference in clinical outcome with either free-fat graft, Gelfoam, or no interposition membrane placed in the laminectomy defect after nerve root decompression. Summary of Background Data, Epidural fibrosis has been considered a cause of recurrent symptoms after lumbar laminectomy, and numerous materials have been evaluated for prophylaxis of the ''laminectomy membrane.'' These have been mainly histologic and animal studies with no data correlating clinical symptoms and postoperative epidural scar formation. Methods. One hundred fifty-six patients who were treated surgically for lumbar disc herniation were randomly assigned to one of three groups and followed prospectively for at least 1 year. Thirty-three of these patients were received magnetic resonance imaging evaluations after 6 months by an independent radiologist who graded the amount of epidural scar formation. The patients were assessed at 1 year and given a rating of excellent, good, fair, or poor, and the scar graded as none, minimal, or moderate. Results. Although 97% of all patients improved, 83% were rated excellent or good. There were no statistical differences between the three groups clinically and radiographically. Patients with workers compensation had a statistically significant lower success rate (P < 0.001), Conclusions. Clinical outcome after lumbar disc surgery does not correlate with the use or type of interposition membrane used to prevent epidural fibrosis.