A Biomechanical Cadaver Comparison of Suture Button Fixation to Plate Fixation for Pubic Symphysis Diastasis

Objectives: To determine whether suture button fixation of the pubic symphysis is biomechanically similar to plate fixation in the treatment of partially stable pelvic ring injuries. Methods: Twelve pelvis specimens were harvested from fresh frozen cadavers. Dual-x-ray-absorptiometry (DXA) scans were obtained for all specimens. The pubic symphysis of each specimen was sectioned to simulate a partially stable pelvic ring injury. Six of the pelvises were instrumented using a 6 hole, 3.5 mm low profile pelvis plate and six of the pelvises were instrumented with two suture button devices. Biomechanical testing was performed on a pneumatic testing apparatus in a manner that simulates vertical stance. Displacement measurements of the superior, middle, and inferior pubic symphysis were obtained prior to loading, after an initial 440 N load, and after 30,000 and 60,000 rounds of cyclic loading. Statistical analysis was performed using Wilcoxon-Mann-Whitney tests, Fisher\u27s exact test, and Cohen\u27s d to calculate effect size. Significance was set at p \u3c 0.05. Results: There was no difference between groups for DXA T scores (p = 0.749). Between group differences in clinical load to failure (p = 0.65) and ultimate load to failure (p = 0.52) were not statistically significant. For symphysis displacement, the change in fixation strength and displacement with progressive cyclic loading was not significant when comparing fixation types (superior: p = 0.174; middle: p = 0.382; inferior: p = 0.120). Conclusion: Suture button fixation of the pubic symphysis is biomechanically similar to plate fixation in the management of partially stable pelvic ring injuries