Effect of sacral buttress technique in Ramathibodi spinal system fixation on L5-S1 motion

This is a retrospective study which reviewed the effects of the sacral buttress technique of Ramathibodi Spinal System (RSS) instrumentation for degenerative conditions of the spine on L5-S1 motion. The inclusion criteria included patients who were treated by wide decompression and fusion of the lumbar spine. Two treatment groups of a different fusion technique were identified; the first group was treated by conventional fixation and the second group was treated by the sacral buttress technique. The objective of this study was to evaluate the effect on L5-S1 motion and translation between the conventional group and sacral buttress group. The material consisted of 66 patients who were operated from 1996 to 1999 for degenerative conditions of the lumbosacral spine. The conventional group included 25 patients in whom instrumentation was stopped at the fifth lumbar spine and the buttress group consisted of 41 patients who underwent the sacral buttress technique with RSS fixation. Dynamic lateral radiographs were measured to determine the motion and translation before and after surgery. In the group with sacral buttress technique, post operation decrease in motion of the lumbosacral joint was statistically significant. Reduced motion was also associated with the level of fusion. The use of the sacral buttress technique with RSS led to significant control in lumbosacral motion without the need for screw fixation to the sacral spine. The usefullness of this technique is a valuable adjunct to spinal fusion in patients who undergo decompressed spinal surgery and may prevent the junctional problem of fusion at this segment and also the upper end of the above fusion level.