The lateral radiograph is useful in predicting shortening in 31A2 pertrochanteric hip fractures.

BACKGROUND We sought to determine if angulation or translation measured on the lateral preoperative injury radiographs of patients with 31A2 pertrochanteric fractures is related to excessive postoperative shortening when treated with a sliding hip screw. METHODS We retrospectively reviewed the radiographs of consecutive patients with hip fractures treated at a level I university trauma centre between 2003 and 2008. Patients with 31A2 pertrochanteric fractures treated with a sliding hip screw were identified through a search of medical records. The study variables were angulation and translation on the preoperative injury lateral radiograph. The outcome measure was radiographic evidence of fracture shortening, measured as the change in length of sliding hip screw visible outside the barrel between the time of fixation and final follow up. RESULTS Of the 131 patients treated, 23 met our inclusion criteria and had sufficient follow-up (mean 6.4 mo). The average shortening for 31A2 fractures with angulation on the injury lateral radiograph was 1.83 (95% confidence interval [CI] 1.18-2.47) cm, compared with 0.93 (95% CI 0.49-1.36) cm for fractures with no angulation (p = 0.019). There was no statistical difference in quality of reduction, tip-apex distance, Orthopedic Trauma Association (AO/OTA) classification or incidence of lateral wall fracture across groups based on the presence of angulation. CONCLUSION Angulation on the lateral preoperative injury radiograph may be useful in predicting excessive shortening in 31A2 pertrochanteric fractures. Further investigation is warranted to confirm this result and to identify the role of other predictors, such as fracture comminution.