Houston Methodist. Leading Medicine

Lower Spine News

Stabilizing the Spine While Preserving Motion

Surgeons continue to look for better ways than spinal fusion to treat chronic low back pain (LBP). In this study, a new method called the fulcrum assisted soft stabilization (FASS) was tested on human cadavers and on wood and rubber spine models.

Spinal fusion gives a stable spine but limits motion at that level. The goal of this dynamic stabilization is to hold the spine stable while keeping normal motion. Taking abnormal loads off the disc is also important.

Stainless steel screws were placed into the pedicles on both sides of the vertebra. The pedicles are the bony projections on either side of the vertebra that form the arch around the spinal canal. Screws were placed in the vertebra above the damaged disc and in the vertebra below the damaged disc. A plastic rod was placed vertically between the two screws. Then a rubber "O" ring was wrapped vertically around the ends of the screws.

The authors explained how the use of the plastic fulcrum is to unload the disc. This also helps keep the spine in a position of extension or lordosis. The "O" ring acting as a ligament applies a compressive force to open up the disc space slightly. Using the fulcrum and ligament together holds the spine in its proper position and spreads the load across the disc and joints. Normal motion occurs without abnormal slipping and sliding.

The spines with the FASS in place were connected to a special machine to test motion and loading. Using trial and error the researchers were able to find the length of the screw that unloaded the disc by 50 percent and then by 100 percent. They found that range of motion decreased and stiffness increased as the disc was unloaded more and more.

The new FASS system can unload the disc by using a fulcrum in front of a ligament wrapped around the pedicles. The system controls motion and maintains the lumbar spine in lordosis. With the ligament alone, the lordosis was present but the disc pressure increased. This is another step toward a future means of treating LBP without fusion. The FASS may be perfected to the point it can stabilize the spine yet still allow normal motion and position.

Dilip K. Sengupta, MCh, and Robert C. Mulholland, FRCS. Fulcrum Assisted Soft Stabilization System. In Spine. May 1, 2005. Vol. 30. No. 9. Pp. 1019-1029.


*Disclaimer:* The information contained herein is compiled from a variety of sources. It may not be complete or timely. It does not cover all diseases, physical conditions, ailments or treatments. The information should NOT be used in place of visit with your healthcare provider, nor should you disregard the advice of your health care provider because of any information you read in this topic.
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