Introduction
Back pain is a leading cause for physician visits, with approximately 6080% of the US population experiencing episodes of acute low back pain at least once in their lives. While the majority of these patients improve with conservative care, a significant number become chronically debilitated and require surgical intervention. Historically, these patients are treated with fusion in lumbar spine or discectomy in cervical spine. Total disc replacement provides spine surgeons a proven alternative. Just like knee and hip arthroplasty, motion preservation of the spine is expected to make a significant impact on the surgical treatment of degenerative disc disease (DDD).

ProDisc
ProDisc was developed using the ball and socket concept successfully used in joint replacement implants for over 40 years. The ProDisc ball and socket implant design has been used clinically since 1990 and continues
to demonstrate excellent long-term clinical results. The ProDisc surgical technique, instrumentation, and implant function as a unified system. It provides a safe and reproducible implantation through a midline, mini open anterior approach. The implant is comprised of three implant componentstwo cobalt chrome alloy (CoCrMo) endplates, and an ultra-high molecular-weight polyethylene (UHMWPE) inlay. These materials have a long-term history of safe and effective use in joint replacement, which in the case of hips and knees is a much more demanding mechanical application.

ProDisc-C
When conservative attempts fail to alleviate the pain and neurological deficits caused by degenerative disc disease, the most common treatment is surgical decompression of the affected nerves and spinal cord. Cervical decompression is most often accomplished via an anterior discectomy. Discectomy involves the surgical removal of soft disc herniations that press against the spinal cord or nerve roots. Most cervical discectomies are followed by the insertion of a bone graft into the space to fuse the adjacent vertebrae together. This is known as an anterior cervical discectomy and fusion (ACDF). ACDF is considered successful when the motion at a painful motion segment is stopped. However, stopping the motion at a vertebral segment changes the mechanics of the cervical spine (which is designed for motion and flexibility). This results in the transfer of the loads and stresses to the adjacent vertebral segments and often leads to the recurrence of neck and arm pain over time. Like ACDF, cervical total disc replacement (CTDR) is intended to reduce pain by allowing for the removal of the diseased disc while restoring disc height. The difference is that CTDR also attempts to replicate a normal physiologic range of motion without increasing the stress and strain on adjacent cervical segments. The ProDisc-C total disc replacement provides the potential for motion in a single vertebral segment from C3-C7. The ProDisc-C provides for immediate fixation into the vertebral bodies through a midline keel that is orientated anterior-posterior. The bone contacting surfaces of the inferior and superior plates as well as both keels are titanium plasma spray coated to allow for long-term fixation by bony integration. Additionally, the implant is provided in a variety of sizes to allow the surgeon to accurately match the patients anatomy.

In the US, the ProDisc-C recently completed the 2 year follow-up of a multicenter, prospective, randomized, controlled clinical trial. The purpose of the trial was to compare the safety and effectiveness of ProDisc-C to traditional spinal fusion surgery for the treatment of symptomatic degenerative disc disease in the C3-C7 cervical vertebral segments. Over 200 patients were randomized to ProDisc-C or ACDF surgery in a 1:1 ratio. 15 clinical sites were selected to assess the primary endpoints of the study which included key clinical outcomes such as the neck disability index (NDI), neurologic parameters, and removal or revision rates. The results of this study will be available soon.