Measurement of Nitinol Recovery Distance Using Pseudoelastic Intramedullary Nails for Tibiotalocalcaneal Arthrodesis

Foot Ankle Spec. 2016 Dec;9(6):494-499. doi: 10.1177/1938640016656786. Epub 2016 Jul 9.


Background: Tibiotalocalcaneal arthrodesis is a salvage procedure for patients with complex disease of the ankle and subtalar joints. Despite the clinical efficacy and mechanical advantage of intramedullary nails, complications, such as nonunion, are common. It may be possible to sustain compression in the face of bone resorption and implant loosening over the course of healing using a novel pseudoelastic intramedullary nail with an internal nitinol element.

Methods: We identified 15 patients with average age of 54.7 years (range, 28-75 years) who had undergone a tibiotalocalcaneal arthrodesis using a pseudoelastic intramedullary nail. Serial radiographs were used to determine the amount and rate of nitinol element migration over the first 3 postoperative months.

Results: Postoperatively, there was at least 2.38 mm of nitinol element migration proximally with mean of 5.58 mm (± 1.38), (range, 2.38-8.11 mm). Average follow-up time was 195 days (± 106.3), (range, 89-490 days). On average, 86% of the total recovered distance took place within the first 39.7 days (±10.03).

Conclusions: The nitinol element recovers distance when stretched intraoperatively and maintains moderate compression in response to bone resorption. Further studies are needed to assess if this increased compression lends itself to higher fusion rates than traditional intramedullary nails.

Levels of evidence: Therapeutic, Level IV: Case series.

Keywords: nitinol; pseudoelastic intramedullary nail; tibiotalocalcaneal arthrodesis.