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Lumbar (Low Back) Dynamic Stabilization - A Patient's Guide

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Traditionally, spinal fusion has been offered to patients who suffer from lumbar (low back) degenerative disc disease, spinal stenosis or spondylolisthesis. Early fusion procedures performed without instrumentation (e.g. rods) proved to be more prone to failed fusion (pseudofusion) than instrumented fusion. As metal implants were developed and used, failure rates declined. However, despite this improvement, fusion is known to significantly alter spinal biomechanics, which is a concern for causing premature disc degeneration at levels neighboring fusion, especially in young patients.

Why do metal implants affect spinal biomechanics?
Partly, because stainless steel and titanium are rigid and far less compliant than bone. These rigid implants can cause significantly more stress on the neighboring levels of the spine. Some research has shown excessive motion at the neighboring non-instrumented levels in the spine. Both of these effects are felt to contribute to premature degeneration of nearby levels, or what is termed adjacent segment disease. This degeneration can either occur in previously healthy levels, or accelerate the breakdown of levels with early signs of disease. Adjacent segment disease is associated with worsening disc disease, additional bone spur formation, and overgrowth of the spine's joints (facet joints) which can cause narrowing of the spinal canal and further nerve compression.

degenerative disc disorders, bulging and herniated discs

 

facet joint, labeled

 

How is dynamic stabilization different?
Dynamic stabilization, also called flexible or soft stabilization, is a growing area of spine surgery that potentially can reduce some of the problems inherent with metal implants. The long-term goal of dynamic stabilization is to treat the current problem and simultaneously reduce adjacent segment disease.

Dynamic stabilization uses flexible materials (constructs) to stabilize the affected level or levels without transmitting excessive forces. The flexible portion of the construct limits excessive motion while allowing a degree of mobility. Dynamic stabilization also reduces the load on the spine's joints (facets) and disc space, which may reduce pain.



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Updated on: 02/01/10
Jeffrey C. Wang, MD
Certainly motion preservation and lumbar dynamic stabilization is a very timely topic and of high interest to clinicians and patients who deal with significance spinal pathologies. Spinal fusion is an outstanding procedure but does have limitations. Patients are known to develop adjacent segment disease which, statistically does not increase by the presence of a spinal fusion. However, this loss of motion is at least of theoretic concern. This article by Dr. Highsmith on Lumbar Dynamic Stabilization is an outstanding review and an outstanding justification for the exploration into the area of lumbar dynamic stabilization. I personally feel that this area needs to be explored and certain novel technologies that are currently developed may represent significant advances and may change the way we currently treat our patients.

However, as with any type of new technology we must approach the results with caution and strive to find conclusive data that definitively shows that these newer technologies are beneficial and do not cause any increase in complication rates. As we have seen with some of the devices that have been developed throughout in the recent past, promising initial results may certainly prove later to have perhaps less potential benefit than initially thought. While I do believe that these novel areas need to be explored, we need to approach them cautiously. In addition, despite how successful any device may be, there has never been a prosthesis or device that has been implanted in a patient that is not at one point needed to be revised either from an infection or failure or dislodgement or other type of potential complication that can occur. We must maintain patient safety as our primary goal and approach this promising technology very cautiously.

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