Abstract

Introduction: Disc arthroplasty is gaining popularity for treatment of low-back pain caused by degenerative disc disease (DDD). As total disc arthroplasty is a relative aggressive treatment with high revision risk efforts have been put into the development of less invasive methods resulting in the development of the NUBAC disc arthroplasty system. This abstract describes the design rationale and the preliminary clinical results obtained for the NUBAC. Methods : The NUBAC is designed to mimic the natural kinematics of an intact disc and to restore or maintain the load sharing capabilities of the index disc by preserving most of the annulus, ligaments and endplates. Implant insertion is compatible to any surgical approach and minimally invasive. The design rationale of the NUBAC has been demonstrated in as series of human cadaver studies as part of its preclinical evaluation. Aspects investigated were restoration of disc height, maintenance of segmental motion and stability, endplate fatigue strength and static-load-to-failure. A prospective multicenter study with 131 patients investigated pain and function parameters. Results: Cadaver studies have shown that the device can restore the disc height and segmental mobility and stability to the intact state. No visible endplate or cancellous bone fractures were evident after 100,000 cycles of fatigue testing. Static-load-to-failure has shown that the failure load of the surgical repaired specimen does not decrease. The NUBAC has been implanted in the lumbar spine of 131 patients at 135 levels from L2-S1 with more than 90% at L4/5 and L5/S1 via all three major surgical approaches; posterior, lateral and antero-lateral. Pain relief was investigated by VAS and showed good pain relief from six weeks through 2 years (VAS 78 at baseline to 30, 30, 26, 26 and 23 at 6 weeks, 3, 6 months and 1 and 2 years, respectively). Function using the ODI showed continuous improvement at all visits (53 at baseline to 31, 26, 23, 23 and 10 at 6 weeks, 3, 6 months and 1 and 2 years, respectively). Conclusions: Preclinical studies show that NUBAC is able to restore disc height, maintains segment mobility and stability. Clinically the pain relief and improvement of function suggest that the NUBAC is a feasible, less invasive alternative for treatment of low back pain caused by DDD.