Bone-Anchored Implant to Reduce Reherniation: Effect of laminar bone removal on segmental stability and clinical outcomes

Tung Nguyen, MD, Claudius Thomé, MD, Peter Douglas Klassen, MD, Adisa Kursumovic, MD

Introduction

Laminectomy and laminotomy are often required to decompress neural tissue in several spinal procedures including central decompression and discectomy.  A randomized control trial (RCT) comparing outcomes after discectomy-alone and discectomy with a bone-anchored implant (Barricaid) showed that the implant reduced reherniation and reoperation rates by 51% and 45%, respectively at two-years. During surgery of that RCT, the amount of bone removed from the lamina was evaluated for both the discectomy-alone group and the Barricaid group. Results showed that, when compared to the surgeon’s typical discectomy patient, 50.7% of Barricaid subjects had an “above average amount of bone removal” as compared to 23.4% of Control patients.¹ 

Objective

To investigate the effects of increased bone removal in the Barricaid group, which have not previously been investigated.

Methods

This is a retrospective analysis of a 554 patient RCT, which investigated the use of a bone-anchored implant (Barricaid). During surgery, laminotomy was completed, and the surgeon qualitatively scored the amount of bone removal relative to their average discectomy procedure. Potential responses were above average, average, or below average bone removal. Correlations were evaluated between the amount of bone removal and 1) the subject’s segmental instability assessed via rotational and translational (A-P) range of motion (ROM) during flexion-extension and change in spondylolisthesis; and 2) disability assessed through VAS leg, VAS Back, ODI, and reoperation to treat instability.

Results

Above average bone removal occurred in 50.7% of Barricaid subjects.  When comparing subjects with “above average” bone removal to subjects with “equal to or less than average” bone removal, segmental instability and disability scores were not found to be statistically different. (Radiographic Stability – Flexion-Extension: p=0.47, Translational ROM: p=0.89, Change in Spondylolisthesis: p=0.4347; Disability – VAS leg: p=0.54, VAS Back: p=0.54, ODI: p=0.51, Reoperation for instability: p=0.68).

Conclusion

Bone-anchored implant has previously been shown to reduce reherniation and reoperation rates by ~50%. This study showed that, although Barricaid patients require more bone removal compared to a typical discectomy, these patients did not suffer from an increase in instability or disability.