Summary
It is not clear whether dynamic or rigid fixation is better in anterior cervical discectomy
and fusion for patients with degenerative disc disease based on evidence from two
small to moderate sized randomized controlled trials. Functional scores, pain, and
fusion appear to be similar in patients treated with dynamic and rigid plates, but
implant complications may be more frequent for the rigid plate group and loss of lordosis
may be greater in the dynamic plate group based on the results from one randomized
controlled trial. Results did not clearly favor one treatment over the other which
may in part be due to bias from variable, low follow-up rates. To better understand
the differences in outcomes between dynamic and rigid fixation in anterior cervical
discectomy and fusion, additional larger, methodologically rigorous trials are needed.
Clinical notes
Bryan Ashman, Australia
Is dynamic plate fixation better than rigid locking-screw fixation in anterior cervical
discectomy and fusion? The two studiest reviewed suggest that it may be so.
Although anterior plate fixation after cervical discectomy and interbody grafting
has been shown to enhance fusion rates for multilevel procedures, instances of screw
back-out and plate failure of the original systems lead to the development of more
rigid locking-screw devices. Concerns about the potential for stress-shielding of
the interbody grafts in turn lead to the development of dynamic screw-plate devices.
These studies suggest that although the dynamic systems allow more local kyphosis
to develop, this is not functionally important and the speed of graft incorporation
and lower implant failure rates favour their use.
However we are already seeing the development of the next generation of stand-alone
anterior interbody implants which incorporate internal fixation devices. Time will
tell whether these too are an improvement or not.
