Anterior cervical discectomy and fusion (ACDF)Dynamic versus rigid fixation: does having a rigid fusion affect outcomes in spine surgery?
30 December 2009 (online)
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.
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.