Extract
Intervertebral disc replacements have been under design for over three
decades but are now receiving increased attention. This is largely due to
several devices that have received Investigational Device Exemption status
from the United States Food and Drug Administration, resulting in clinical
trials in the United States. There is tremendous early enthusiasm for the
concept of disc replacement and motion preservation as an alternative to
arthrodesis, with the hope that adjacent segment degenerative changes can be
averted. Skeptics hold the position that adjacent segment changes are due more
to the individual's genetic predisposition and normal aging than to the
mechanical changes resulting from a spinal arthrodesis. In addition, there are
potential long-term consequences to disc replacement that remain unknown.
These issues include failure, wear debris, and the effects of stress-risers as
patients age and become osteopenic. The two basic categories of disc
replacements are nuclear replacements and total disc replacements. The
critical issues pertaining to total disc replacements were recently explored
in a symposium at the 2003 Annual Meeting of the American Orthopaedic
Association in Charleston, South Carolina, and are summarized in this
review.