Outcomes of Threaded Intramedullary Headless Nail Fixation for Metacarpal Fractures

Metacarpal fractures are common and may require operative treatment; however, there is no gold standard fixation technique. K-wires are used for simplicity and flexibility but require immobilization and can lead to complications. Dorsal plating provides greater stability than K-wires but is subject to its own limitations. Intramedullary threadless nails have reduced time to union and improved range of motion (ROM) but may not provide the stability of plating. Intramedullary screws allow rapid return to activity and increased stability; however, compression forces may shorten metacarpals, producing non-anatomic reduction. The ExsoMed INnate^TM threaded intramedullary nail (ExsoMed, Aliso Viejo, CA, USA) was developed with tall threads, a diameter fitting the metacarpal canal cortical purchase, stability, and no compression to prevent fracture displacement and shortening. We designed a prospective study to evaluate INnate^TM nail fixation in metacarpal fractures. Visual analog scale (VAS) pain score, total active motion (TAM), radiographic union, and return to normal activity were recorded at each postoperative visit. Descriptive statistics were performed for endpoints. Fifty-eight patients were included with a median age of 38.7 years. The INnate^TM nail was used in 80 fractured metacarpals. The 4th and 5th metacarpals were most frequently involved. The most common mechanisms of injury were blunt trauma and motor vehicle collisions. Approximately 31% of patients had multiple, concurrent fractures (16 patients required two nails; two required three nails). The mean follow-up was 9.9 weeks. The mean time to radiographic union was 9.1 weeks. The final visual analog scale (VAS) pain score was 1.1. The mean time to return to work and/or normal activities was 9.7 weeks, and the mean percentage of normal activity resumed was 89.1%.