A multicenter, prospective, randomized study protocol to demonstrate the superiority of a bone-anchored prosthesis for anular closure used in conjunction with limited discectomy to limited discectomy alone for primary lumbar disc herniation

Peter Douglas Klassen, Robert Hes, Gerrit Joan Bouma, Sandro Eustacchio, Martin Barth, Adisa Kursumovic, Senol Jadik, Volkmar Heidecke, Richard Bostelmann, Claudius Thomé, Peter Vajkoczy, Hans Peter Köhler, Javier Fandino, Richard Assaker, Erik Van de Kelft, Susanne Fröhlich, Wimar van den Brink, Jason Perrin, Jasper Wolfs, Mark Arts, Frederic Martens


Background: Same-level reherniation and progressive degeneration with disc height loss are main causes of poor outcome after discectomy and may necessitate reoperation.  A novel prosthesis for anular closure was developed to address these causes.

Methods: The design of a multicenter, prospective, randomized, post-market superiority trial comparing limited lumbar discectomy augmented with this device (intervention group) with limited lumbar discectomy alone (control group) is presented.

Results: Patients with single-level (L1-S1) posterior or posterolateral disc herniation and radiologic confirmation of neural compression for whom at least six weeks of conservative treatment has failed are eligible.  Patients must have posterior disc height ≥5 mm at index level and baseline Oswestry and VAS leg pain scores of ≥40/100.  Intraoperatively, subjects meeting anular defect size criteria post-discectomy (4-6 mm tall and 6-10 mm wide) will be randomized to study groups in a 1:1 ratio using centralized, web-based software. A Bayesian statistical approach will be used to enroll 400 to 800 subjects who will be followed for at least 24 months.  Two co-primary endpoints will be assessed at 24 months: 1) a composite of leg pain, clinical function, disc height maintenance, and absence of reherniation, reoperation, and device failure; and 2) absence of reherniation based upon independent radiologic analysis.  

Conclusions: This type of analysis is becoming increasingly important as governments and health insurers continue to be pressured to spend limited healthcare funding wisely.


Disc herniation, Reherniation, Anular closure, Discectomy

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