Artificial cervical disc replacement--an update.

Rationals for total disc replacement Dynamic reconstruction of a degenerative “functional spinal unit” (FSU) is a rapidly growing field in spinal surgery. So far anterior cervical discectomy and fusion (ACDF), first described by Smith and Robinson and by Cloward in the 1950s, is the most common surgical procedure proven successful in the treatment of symptoms caused by cervical degenerative disc disease (DDD) including disc herniations and other compressive pathologies. The main goal of these techniques is the decompression of neural structures and to re-establish segmental stability with restoration of the physiologic curvature of the treated segment(s). Restoration of stability and sagittal rebalancing can only be achieved with the fusion of one or more cervical segments. In the cervical as well as in the lumbar spine there has been increasing concern about acceleration of adjacent segment degeneration which might result in further surgical procedures. In the late 1980s Cummins tried to address the problem of maintaining motion in the cervical spine after surgery by introducing a simple ball and a socket type of cervical joint with entirely congruent surfaces. This technique preserved in most cases a limited segmental motion and it was concluded that further investigations were warranted to prove the efficacy of this procedure. The promising early results seen in prospective randomised studies of total disc replacement in the lumbar spine have encouraged the development of similar solutions for the cervical spine in order to create an alternative to fusion procedures.