Introduction: Lag screw cut-out is one of the major postoperative complications on femoral trochanteric fractures. However, precise analyses of excessive sliding and lag screw cut-out were limited. The purpose of this study was to investigate the factors that induce this unfavorable event.
Methods: From April 2010 to April 2013, 226 patients were operated in our institute using a short femoral nail. Among them, 177 patients (29 males and 148 females) with a mean age of 84 years (60-97 years), who were followed up >3 months, were included in this study. The postoperative sliding distance, fracture type (AO/OTA classification), tip-apex distance (TAD), reduction pattern in the postoperative X-ray (antero-posterior and lateral views), bone quality (canal flare and cortical indices), walking ability at the time of pre-injury and final follow-up, and complications were investigated retrospectively.
Results: The mean sliding distance was 3.7 mm, and one cut-out case (0.6 %) was observed. The sliding distance of the AO/OTA 31-A2 fractures was significantly longer than that of the A1 fractures (p < 0.0001). Regarding the reduction pattern, the sliding distance of the intramedullary type was longer than that of the extramedullary and anatomical types in the lateral view (p < 0.01, p < 0.001, respectively). Further, even in the medial and anatomical types, where the reduction patterns are recommended in the antero-posterior view, the sliding distance of the intramedullary type was significantly longer than that of the anatomical type in the lateral view. There was no correlation of bone quality with the sliding distance.
Conclusions: Because the sliding distance increased in the intramedullary type in the lateral view of unstable fractures, an accurate reduction in the lateral view at surgery is important, particularly in unstable fractures.