Cervical Disc Arthroplasty by Vladimir Sinkov MD
Cervical Disc Arthroplasty
By Vladimir Sinkov MD
Cervical radiculopathy is a common problem that can cause significant pain and disability. The annual incidence is estimated to be 83 per 100,000 persons. The most common cause is cervical disc herniation compressing cervical nerve roots. The symptoms of cervical radiculopathy include pain, numbness, weakness, and loss of reflexes in one or both arms. Initial treatment options include rest, activity modification, physical therapy, anti-inflammatory medications, cervical manipulation, and steroid injections. If conservative therapy fails or if symptoms are severe and progressive, surgery may be indicated to remove the pressure off the nerves. Most of the time the disc herniation needs to be addressed by removing the entire cervical disc through the front of the neck in order to relieve the pressure on the nerve roots. Once the disc (that connects the vertebrae together) is removed, the involved spine segment becomes unstable. Since 1950’s the most effective surgery to address this has been anterior cervical discectomy and fusion (ACDF) that achieves complete decompression of neural elements and subsequent stabilization of the segment by placing bone graft and hardware in place of the disc in order to achieve bony fusion between the two vertebra. This procedure is very effective with published clinical success rates at 90%-95% and fusion rates of 95%.
Common long-term consequence of ACDF, however, is adjacent segment degeneration. Once the operative level is successfully fused, more mechanical stress is transmitted to the discs above and below the fusion. This can accelerate degeneration of those discs, requiring further treatments including possibility of additional surgery. The rate of symptomatic adjacent segment degeneration has been shown to be 2.5%-3% per year. This means that the younger and the more active the patient is when they get the fusion, the more likely they are to eventually develop arthritis, pain, and new nerve compression in the future. Two thirds of the patients with the adjacent segment degeneration eventually require additional fusions.
This fact led to development of technologies to address cervical radiculopathy without causing stress at adjacent levels. The modern designs of cervical total disc replacement (CTDR) implants were introduced in the United States in early 2000’s. Since then, multiple versions of these devices were developed, cleared by FDA, and are currently in use. Multiple randomized, controlled, short and mid-term outcome studies comparing disc replacement and fusion have demonstrated that CTDR procedure was just as effective at treating cervical radiculopathy, while maintaining motion at the operated segment. Disc replacement has been shown to lead to faster recovery and return to work, similar complication rates, and significant decrease in adjacent segment degeneration. Since these devices are relatively new, long-term outcome studies are still pending. One of the most recently approved second-generation devices has been shown to be effective at both one- and two-level disc replacement with clinical outcomes superior to those of ACDF at 7 years post-operatively.
It should be noted that not every patient that has failed non-operative options and needs cervical discectomy would qualify for disc replacement. Exclusion criteria for CTDR are more stringent. Cervical disc replacement is also more technically demanding than fusion and requires additional surgeon training and certification.
Cervical disc replacement is becoming a more and more common-place procedure in the US and will significantly improve outcomes and decrease need for additional surgery among patients with cervical radiculopathy.
Vladimir Sinkov MD