Motion Preservation and Clinical Outcome of Porous Coated Motion Cervical Disk Arthroplasty

BACKGROUND: Artificial cervical disk replacements are commonly used to treat radiculomyelopathy caused by degenerative disk disease. However, long-term disk mobility and an effect on adjacent segment disease have yet to be demonstrated. We report improvements in clinical outcome after disk replacement but also demonstrate potential limitations. OBJECTIVE: To review clinical and radiological outcomes after diskectomy and disk replacement with the Porous Coated Motion (PCM) artificial cervical disk. METHODS: A retrospective review was done of consecutive patients who underwent 1- or 2-level PCM disk replacements. The following criteria were studied: arm pain, neck pain, Neck Disability Index and Short Form-36 questionnaires, and flexion-extension radiographs up to 2 years after surgery. RESULTS: Eighty PCM artificial disks were implanted in 53 patients. Only 17 disks (21%) maintained physiological movement, and complete fusion was seen in 18.8%. One disk replacement was revised because of anterior displacement. There were no complications of infection, cerebrospinal fluid leak, dysphagia, or hoarse voice. Arm and neck pain improved significantly after diskectomy, but Neck Disability Index questionnaires demonstrated a slight improvement that was not sustained by 2 years. Short Form-36 scores demonstrated a trend toward better outcome with time, but it was significant only for the mental domain. CONCLUSION: Clinical improvement was seen after PCM disk replacement, but adequate range of movement was sustained in only 21% of disk replacements over time. Unclear long-term results of this and other disk replacements suggest caution in adopting these new devices as the gold standard.