Annular closure in lumbar microdiscectomy for prevention of reherniation: a randomized clinical trial

Background Context

Patients with large annular defects after lumbar discectomy for disc herniation are at high risk of symptomatic recurrence and reoperation.

Purpose

The present study aimed to determine whether a bone-anchored annular closure device, in addition to lumbar microdiscectomy, resulted in lower reherniation and reoperation rates plus increased overall success compared with lumbar microdiscectomy alone.

Design

This is a multicenter, randomized superiority study.

Patient Sample

Patients with symptoms of lumbar disc herniation for at least 6 weeks with a large annular defect (6–10?mm width) after lumbar microdiscectomy were included in the study.

Outcome Measures

The co-primary end points determined a priori were recurrent herniation and a composite end point consisting of patient-reported, radiographic, and clinical outcomes. Study success required superiority of annular closure on both end points at 2-year follow-up.

Methods

Patients received lumbar microdiscectomy with additional bone-anchored annular closure device (n=276 participants) or lumbar microdiscectomy only (control; n=278 participants). This research was supported by Intrinsic Therapeutics. Two authors received study-specific support morethan $10,000 per year, 8 authors received study-specific support less than $10,000 per year, and 11 authors received no study-specific support.

Results

Among 554 randomized participants, 550 (annular closure device: n=272; control: n=278) were included in the modified intent-to-treat efficacy analysis and 550 (annular closure device: n=267; control: n=283) were included in the as-treated safety analysis. Both co-primary end points of the study were met, with recurrent herniation (50% vs. 70%, P<.001) and composite end point success (27% vs. 18%, P=.02) favoring annular closure device. The frequency of symptomatic reherniation was lower with annular closure device (12% vs. 25%, P<.001). There were 29 reoperations in 24 patients in the annular closure device group and 61 reoperations in 45 control patients. The frequency of reoperations to address recurrent herniation was 5% with annular closure device and 13% in controls (P=.001). End plate changes were more prevalent in the annular closure device group (84% vs. 30%, P<.001). Scores for back pain, leg pain, Oswestry Disability Index, and health-related quality of life at regular visits were comparable between groups over 2-year follow-up.

Conclusions

In patients at high risk of herniation recurrence after lumbar microdiscectomy, annular closure with a bone-anchored implant lowers the risk of symptomatic recurrence and reoperation. Additional study to determine outcomes beyond 2 years with a bone-anchored annular closure device is warranted.