Purpose of study: It has been repeatedly demonstrated that disc denucleation ultimately results in segment destabilization and progressive collapse of disc space. Microdiscectomy alone for the treatment of primary herniated nucleus pulposus (HNP) has been only partially effective because of clinically relevant recurrence. To provide stabilization to the denucleated disc, while eliminating the potential for recurrent herniations, we propose the use of an in situ polymerizable protein hydrogel device (BioDisc). When introduced as a liquid into the denucleated disc space, the implant cross-links to form a durable hydrogel that maintains disc height and segmental stability while preserving motion.Methods used: Fresh calf lumbar segments (single bone-disc-bone [BDB] segment) were modeled as a worst-case stability scenario by full removal of the posterior spinal segments. Baseline compressive properties were obtained by cyclically loading 300 to 1,200 N for 1,000 cycles, and recording compressibility and overall segment height over each cycle. The disc of each BDB segment was then thoroughly denucleated with spinal rongeurs, following an anterior, posterior of posterolateral approach, and re-evaluated under identical test conditions to assess loss of height and segmental stability. The denucleation was then repaired with BioDisc, whereupon the segment was evaluated as above. Subsequently, each BDB segment was cyclically loaded to the equivalent of 1,200 N through 10 million cycles with interval evaluations.of findings: After the removal of the disc nuclear material, BDB segments exhibited an immediate loss in disc height. Repair of the disc denucleation with BioDisc preserved the initial (predenucleation) disc height. During monotonic loading through 10 million cycles, the repaired BDB segment demonstrated a minimal reduction in overall height and retained the axial compressibility of the motion segment. Upon completion of each test, all samples were grossly inspected (by sectioning through the repaired region) and the implanted BioDisc material was observed to be intact within the nuclear space.Relationship between findings and existing knowledge: The BioDisc implant has been shown to possess suitable biomechanical properties to stabilize a denucleated intervertebral disc. Mechanical durability of the implant in a severe model construct was demonstrated through 10 million compressive loading cycles.Overall significance of findings: These data demonstrate the potential utility of BioDisc for the repair of denucleated intervertebral discs in the treatment of HNP.Disclosures: No disclosures.Conflict of interest: Umit Yuksel, and; Steven Walsh: employees of Cryolife Inc.