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RTI's Simmetry Reduces SI Joint Range of Motion


Results from human cadaver study demonstrate that RTI Surgical's Simmetry® Sacroiliac Joint Fusion system provided effective joint fixation, markedly reducing range of motion in the SI joint. RTI acquired the system with its purchase of Zyga in early 2018.

The human cadaveric biomechanical study compared two minimally-invasive techniques for placing primary and secondary threaded implants, examining effectiveness in stabilizing the SI joint. The study also evaluated the link between fixation and bone mineral density, as well as the impact of removing the secondary implant on construct rigidity. Fourteen human cadaveric SI joints were prepared, grafted and fixated using threaded SImmetry implants. 

Results showed a 65% to 71% reduction in joint motion using multiple configurations of the implants, with benefits maintained after repeated loading. These benefits were noted as greater than those seen in previous studies using triangular SI joint implants. (For example, SI-BONE devices are triangular.) Results also showed evidence of immediate fixation.

Sources: RTI Surgical, Inc.; ORTHOWORLD Inc.