Update on cervical artificial disk replacement.

Overview

Cervical disk arthroplasty, one of the emerging motion-sparing technologies, is currently undergoing evaluation in the United States as an alternative to arthrodesis for the treatment of cervical radiculopathy and myelopathy. With both arthrodesis and arthroplasty, the primary surgical goal is thorough decompression of neurocompressive pathology--directly by removal of osteophyte and disk and indirectly by disk distraction. There is, however, one principal difference between arthrodesis and arthroplasty. With a solid fusion, resorption of osteophytes (in accordance with Wolff's law) further enhances decompression. In contrast, osteophyte resorption will not occur with motion-preserving arthroplasty. There are many challenges when deciding between arthrodesis and arthroplasty. Prosthetic performance demands exacting implantation techniques to ensure correct placement, thus placing increasing demands on special instrumentation and surgical skills. It is also important to understand the tribology (the study of prosthetic lubrication, wear, and biologic effects) of disk arthroplasty and to be familiar with currently available information regarding kinematics, basic science, testing, and early clinical results.