The postoperative lumbar spine: evaluation of epidural scar over a 1-year period.

PURPOSE We documented the morphological changes on enhanced MR imaging studies that occur in epidural scar over a period of 1 year after lumbar diskectomy. METHODS The study population was culled from a randomized, multicenter clinical trial designed to evaluate the efficacy of a device inhibiting postoperative epidural fibrosis after single-level, unilateral laminectomy/diskectomy for herniated lumbar disk. Analysis was restricted to 71 control subjects who did not receive the device. All patients underwent surgery after receiving clinical and MR examinations, with follow-up MR studies at 6 and 12 months. Evaluation of all MR images was performed by one interpreter, who was blinded to treatment arm and clinical findings. The extent of epidural scar seen at the 6- and 12-month MR examinations was graded on a scale of 0 to 4 for each quadrant at each imaging section encompassing the surgical level. RESULTS Eighty-five percent of the patients had no change in the amount of anterior epidural scar between the 6- and 12-month MR examinations; 75% of the patients showed no change in the amount of posterior epidural scar between the 6- and 12-month examinations. CONCLUSION The majority of our patients had no change in the amount of epidural scarring visible at enhanced MR imaging over a 1-year period after lumbar laminectomy/diskectomy.