Purpose
To verify the validity of a pedicle screw based posterior dynamic stabilization(PDS).
Materials and Methods
At first, theoretical evidences were reviewed and presented the objections against PDS. The answers were investigated by reviewing the development concepts and clinical evidences of each device.
Results
There is no PDS which has been approved as a dynamic stabilizer by US FDA yet. Dynesis^® and Isobar TTL^® were approved as a fusion adjunct. AccFlex^® and CD-Horizon Legacy PEEK rod^® were approved as a single level posterior lumbar interbody fusion adjunct. Dynesys^® is undergoing an FDA IDE study as a non-fusion dynamic stabilizer. Patient’s symptoms were improved, however, there were scarce controlled studies with simple decompression or fusion surgeries. Furthermore quantitative comparison of improvement was impossible because the subjects were not homogenous. Adjacent segment degeneration was not prevented. Stabilized segments showed further degeneration and there wasn’t a case which showed regeneration of disc. Most of segments were fused or became more stable than physiologic motion and allowance of the PDS. Device failure was reported as 5-21%, however most cases were asymptomatic.
Conclusion
In the light of current evidences, PDS is considered not to prevent the problems which were engendered by fusion surgeries. It is not convincible that PDS has a niche between decompression and fusion surgeries.