The Use of Shape-Memory Alloy Staples (Nitinol) in the Treatment of Pubic Symphyseal Disruptions: Clinical Results and Radiographic Outcomes

Nitinol is a shape-memory alloy that has many diverse applications in the field of orthopedics. There have been no previous investigations reporting clinical or radiographic outcomes of the use of nitinol staples in the definitive stabilization of the pubic symphysis. A retrospective chart review was completed on 42 patients who underwent operative stabilization of pubic symphyseal disruption at an urban level-1 trauma center. Patients treated with pelvic staples alone, or in conjunction with traditional plates and screws, were compared with those treated without the use of a shape memory alloys. Thirty-four patients were included for final analysis (8 staples and 26 controls) in this investigation. Three of eight patients in the pelvic staple group had implant failures, with two having a loss of reduction (25%); this was not significantly different from the seven hardware failures (P = 0.61) seen in the control group without any loss of reduction (P = 0.17). Failures in the nitinol staple group occurred earlier at 17.3 days compared with the control group at 101.7 days (P = 0.003). There were no significant differences between groups with regards to any of the other pre- or postoperative variables investigated. The use of nitinol staples vs. traditional plate and screw constructs for stabilizing the pubic symphysis did not result in more clinical failures. The hardware failures identified in the nitinol staple group occurred significantly earlier in the postoperative period, and were associated with a loss of reduction of the pubic symphysis.