A Biomechanical Study of Graf Pedicle Screw on Lumbar Spondylolisthesis

To understand the applicability of the Graf system to lumbar spondylolisthesis; both vertebral kinematics and load carrying effects were in need of further investigation. A three-dimension geometric and mechanical finite element model was used for the evaluation of the mechanical behavior of a five-vertebra lumbar segment first intact, then injured, and finally corrected by instrumentation. Besides the influence of spinal spondylolishthesis, the outcome of the spinal instrumentation using the Graf cable and the universal rod was also investigated. Spinal instability caused by spondylolisthesis can be restored by using either the Graf or rod instrumentation. Nevertheless, the increased stress on the above adjacent level was founded in the instrumented spine using both systems. The main difference of stress distribution between the instrumented spines using the Graf system, and the rod system was noted in the injured and fixed segment. A flexible system, such as the Graf system, may be a good alternative to prevent the complication of device-related osteoporosis. This finding provides an insight into the ability to make predications about spine surgery and aid surgeons in establishing an ideal stabilization.

並列關鍵字

finite element analysis ； graf system ； spinal instrumentation

國際替代計量

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