For patients with painful conditions originating from the spine, the classic surgical treatment has usually been spinal fusion. Spinal fusion stabilizes the unstable spine (spondylolisthesis) and prevents further collapse of degenerating discs and facet joints which can be a primary source of persistent back pain. For many people, spinal fusion provides significant improvement in their level of pain and quality of life. There are potential drawbacks to fusion however, including loss of motion and creation of a very stiff spinal segment which may increase the stress on the discs and joints above or below the fusion.
Spinal surgery is now evolving from fusion, which eliminates motion, to the goal of motion preservation. The intent of motion preservation is to provide a treatment alternative to spine fusion for patients with pain and loss of function caused by specific back problems, such as lumbar spinal stenosis, facet pain, and degenerative disc disease.
Dynamic stabilization is a motion preservation technology that provides a surgical alternative to traditional fusion. These devices can best be described as an internal brace, allowing controlled movement of the affected segment of the spine, or as an internal traction device, preventing further collapse of the disc and facet joints. It offers a unique approach to stabilization and mobilization of the spine that relies on flexible materials and preserves much of the spinal anatomy.
Dynamic stabilization devices are derived from the pedicle screw and rod constructs used in spinal fusion surgery. Pedicle screws are placed into the bones of the spine from the back and serve as an anchor. With traditional fusion, rigid rods are attached to the screws, creating a rigid construct and eliminating motion. Dynamic stabilization devices consist of either flexible rods or flexible cords and spacers that are attached to the pedicle screws. The goal of this new generation of devices is to allow controlled motion in such as way as to achieve more normal movement of the spine.
Currently, dynamic stabilization devices have been approved for use as an adjunct to spinal fusion. When used in this manner, the device adds stability to the spine and helps maintain proper spinal alignment while the fusion becomes solid. The advantage over a traditional fusion is that the dynamic stabilization construct is much less stiff, which may allow small amounts of motion and help prevent rapid degeneration of the adjacent discs and facets. Some have termed this technique a "soft fusion". Some devices are also being studied or will be studied as stand-alone devices (without fusion).