Introduction: Studies have identified a higher risk of reherniation after lumbar discectomy in patients with larger anular defects. Carragee et al found that the reherniation rate was over five times higher in patients with anular defect widths wider than 6mm, compared to the rest of the patients studied; the reherniation rate was 27%, with recurrences occurring within the first 2.5 years, compared to 1% in patients with slit/fissure type defects.
Anular defect size is not typically measured and is rarely reported in the literature. This study sought to confirm the higher risk of reherniation faced by patients with larger anular defects, by reviewing the results of a discectomy-only cohort from an ongoing RCT of an anular closure device.
Methods: Interim data from the control cohort of an ongoing RCT was reviewed for symptomatic reherniations. A key inclusion criterion for the study are anular defect at least 6mm wide (measured intra-operatively), similar to the definition used by Carragee et al to define their ‘massive defect’ group. A limited discectomy, as defined by Spengler, was performed. Symptomatic reherniations were reported and Kaplan-Meier survivorship was estimated based on time to reherniation, and compared to the data presented by Carragee et al.
Results: 227 patients are included from the discectomy-only cohort. Mean time from surgery was 18 months, with a maximum of three years. Mean volume of nucleus removed was 1.2cc, confirming limited discectomy was performed. Mean defect width was 8.0mm; mean defect size was 39.5mm2. Symptomatic reherniations were observed in 26 patients (11.4%). Kaplan-Meier estimates of survivorship were 88% at 18 months and 81% at three years, compared to 84% and 76% respectively in Carragee et al.
Conclusions: These interim results from an ongoing study of discectomy patients with large anular defects confirm a high early recurrence risk as predicted by earlier studies.
Patient Care: Surgeons should be able to better identify patients at risk for reherniation following primary lumbar discectomy.
Learning Objectives: By the conclusion of this session, participants should be able to identify patients at risk of reherniation due to defect size.