Association between peridural scar and activity-related pain after lumbar discectomy.

The purpose of this study was to investigate the correlation between activity-related pain six months after first surgery for herniated lumbar disc, and the extent of lumbar epidural fibrosis present at the surgical site, assessed by magnetic resonance imaging. The 298 patients who underwent surgery for lumbar disc herniation were studied in a randomized, controlled, double-blind multicenter clinical trial to test the effectiveness of the scar-inhibiting device ADCON-L. Clinical assessments were conducted pre-operatively and at 1, 3, and 6 month intervals post-operatively, and included wound examination, magnetic resonance imaging scar assessment, and the Johns Hopkins activity-related pain questionnaire. In addition, a longer-term follow-up assessment was conducted at 12 months post-operatively. The association between the presence of epidural scar and activity-related pain was analyzed at the 6-month interval, when successful surgical excision of protruding disc material should have eliminated chronic pain. Logistic regression analysis demonstrated a significant association (p = 0.02, odds ratio = 0.7) whereby the odds of extensive scar decreased by 30% for every 31% decrease in activity-related pain score. In addition, those patients receiving ADCON-L at surgery developed significantly less scar in the months following operation (p = 0.01, 6 and 12 months post-operatively). Repeated measures analysis demonstrated that patients who received treatment with ADCON-L at the time of surgery experienced less activity-related pain through the 12-month assessment (p = 0.05). A significant association between extensive epidural scar and activity-related pain is demonstrated. Patients with less scar had less activity related pain, confirming the finding that the use of the scar inhibitor ADCON-L has a positive effect on surgical outcome.