gms | German Medical Science

Objective: Randomized clinical trials (RCT) provide the highest level of scientific evidence as to the safety and effectiveness of new therapies, but can leave questions about the applicability of results to general populations. One important ongoing RCT studies discectomy with anular closure compared to discectomy alone. This report of patients treated with the ACD outside of the trial evaluates whether patients, who meet the trial criteria perform similarly to patients, who do not meet the trial criteria.

Method: Patients from a single-site prospective registry of the ACD were screened against inclusion/exclusion criteria from the ongoing RCT including 6 weeks conservative care, no prior index-level surgery, VAS-leg and ODI ≥ 40/100, posterior disc height ≥ 5 mm and intraoperatively measured anular defect between 4-6 mm tall and 6-10 mm wide. Registry patients meeting and not meeting these criteria were evaluated to identify real-world indications excluded from the trial and to compare ACD performance in the two groups in terms of reherniation, VAS and ODI.

Results: 202 patients were entered in the registry between July 2009 and November 2015, 164 of whom had pre- and post-op (mean 458 days) data. Most common exclusions were <6 weeks conservative care (n=84), VAS leg or ODI <40/100 (n=55), prior discectomy (n=23), and anular defect outside the accepted range (n=29). Overall, 44 patients (27%) met trial criteria (Group 1) and 120 (73%) did not (Group 2). There were no significant differences between the groups in respect to mean follow-up time or most operative characteristics. Due to trial criteria, defect size was different between the groups, and Group 1 had higher pre-op ODI, VAS-leg and VAS-back. Mean outcome scores at latest follow-up were not significantly different between the groups (ODI: 24.2 Group 1, 18.7 Group 2, p>0.15; VAS Leg: 28.2 Group 1, 27.6 Group 2, p>0.96; VAS Back: 38.4 Group 1, 30.5 Group 2, p>0.27). There were 6 (3.7% of 164) symptomatic reherniations, half in Group1 (6.8%) and half in Group 2 (2.5%) (p>0.34).

Conclusions: Patients enrolling in the ongoing RCT are representative of disc herniation patients routinely treated with the ACD, with about one-fourth of the patients in our registry meeting trial inclusion criteria. However, there were excluded populations for whom the RCT data may not be relevant, particularly those with lower pre-op VAS/ODI scores and patients with prior surgery. It is encouraging that patients, who did not meet trial criteria performed well.