Chronic low back pain affects an estimated 70% of adults at some point in their lives, causing lost work time and reducing quality of life. It is believed that sacroiliac joint dysfunction is responsible for persistent low back pain in 10-25% of these cases, and a review of literature by Hansen et al. (2012) found that many current treatment options, both surgical and nonsurgical, do not definitively demonstrate successful pain relief. Surgical fusion is highly invasive, but is a viable option when more conservative treatments do not relieve pain; therefore, there is a need for techniques that will lead to sacroiliac joint fusion while minimizing risk. NuTech Medical, Inc. has developed the SIFix®, a new sacroiliac joint fusion technique that utilizes a machined allograft for a posterior approach. The goal of this research is to investigate whether the SIFix® will reduce motion in the sacroiliac joint immediately following surgery. A reduction in sacroiliac joint motion combined with the osseous bridge provided by the SIFix® is expected to lead to bony growth and eventually joint fusion, alleviating pain from sacroiliac joint dysfunction. A servohydraulic mechanical testing system was used to apply loads to eight cadaver specimens, both before and after the SIFix® was inserted. Measurements were taken first in simulated double-leg stance, then in simulated single-leg stance. Displacements and rotations were calculated as the motion of each ilium relative to the sacrum, as measured with an optical motion tracking system. Difficulties were encountered with the surgical procedure, with six of the sixteen sacroiliac joints tested considered a surgical success. As expected, the greatest magnitude of motion was in nutation/counter-nutation. Though the mean nutation/counter-nutation of the SI joints did decrease, the difference was only significant in peak-to-peak relative motion in single-leg stance, decreasing from 0.23° to 0.16° (p = 0.020). This was the only parameter in which all joints examined showed a decrease from the pre-insertion trial; differences in nutation/counter-nutation were not significant in single-leg total relative motion (p = 0.14), double-leg total relative motion (p = 0.40), or double-leg peak-to-peak relative motion (p = 0.19). Coupled with the small number of viable samples and other potential limitations of the study, it could not be determined if the SIFix® would provide a reduction in sacroiliac motion immediately following surgery. Recommendations for future work are to eliminate potential sources of error in the optical tracking system, including refining the surgical procedure.
|Commitee:||Feldman, Dale, Lemons, Jack|
|School:||The University of Alabama at Birmingham|
|School Location:||United States -- Alabama|
|Source:||MAI 56/04M(E), Masters Abstracts International|
|Keywords:||Allograft, Biomechanics, Joint fusion, Sacroiliac joint|
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