Humeral shaft butterfly fractures managed with intramedullary nail: could the third fragment features predict the fracture healing time?

To assess the impact of the radiological features of the third fragment on the outcome of humeral shaft fractures type 12-B managed with endomedullary nails. We retrospectively evaluated a series of 80 patients, divided into 3 groups, according to the fracture healing time: within 6 months (group-A), between 6 and 12 months (group-B) or fracture non-union after 12 months (group-C). In 26 patients out of 80 the fracture healing was observed at 6 months follow-up; in 47 out of 80 at 12 months after trauma and in 7 out of 80 no fracture healing was observed at 12 months follow-up. Regression analysis showed that the third fragment displacement and angulation are the most important features that affect the fracture healing. The mean third fragment dislocation (cut-off: 12 mm) is the main parameter to influence the fracture healing within or in more than six months.