Introduction: Studies investigating the outcomes of limited discectomy typically report results on a general discectomy population. High rates of lumbar disc reherniation, however, would indicate a treatment gap that may be masked without sub-group analysis. The objective of this study was to evaluate whether such a treatment gap exists in a subgroup of the limited discectomy population having large / massive anular tears and the outcomes of a bone-anchored anular closure device (Fig.1) aimed at reducing early reherniation rates (=90 days).
Methods: Prospective, multicenter, randomized (1:1), controlled trial comparing outcomes of patients receiving standard limited discectomy only (control; n=278) or limited discectomy with anular closure device (ACD) (n=272) for symptomatic single-level posterior/posterolateral disc herniation (L1-S1). Anular defect inclusion criteria: 4-6mm (height) by 6-10mm (width). Symptomatic reherniation rates within 90 days were compared between treatment groups using Fisher’s exact test (p=0.05).
Results: Preoperative demographics and post-discectomy measures were similar across groups (p=0.321). Overall symptomatic reherniation rate within 90 days for both groups combined was 3% (17/550). The control group accounted for 82% (14/17) of reherniations. Rate of reherniation in the ACD group was significantly decreased versus controls (p=0.01). A clinically meaningful finding was that the entire study population had already accrued a third of the symptomatic herniations within 90 days as has been reported at 8 years in the generalized discectomy literature.
Conclusions: Early rehernation rates observed in this multi-center study demonstrate a treatment gap within a high-risk discectomy subgroup, particularly for the control group. At 90 days, this subgroup is on a trajectory to surpass long-term failure rates in the general discectomy population, perhaps even by 2 years. Closing the treatment gap will require more durable means of anular closure such as ACD implantation, which significantly reduced the reherniation rate in these high-risk patients.
Patient Care: An unmet need in a high-risk subgroup of the discectomy population has been identified. The outcomes of this analysis show that an ACD can potentially mitigate the early postoperative risk of reherniation in this at-risk population, providing the patient with the greatest likelihood of long-term success
Learning Objectives: By the conclusion of this session, participants should be able to discuss/identify:
1. Whether limited discectomy, large anular defect patients represent a sub-group for which a treatment gap exists
2. Whether an ACD decreases risk of early postoperative reherniation to close the treatment gap.