Reliability of Predictors for Screw Cutout in Intertrochanteric Hip Fractures

BACKGROUND:Following internal fixation of intertrochanteric hip fractures, tip apex distance, fracture classification, position of the screw in the femoral head, and fracture reduction are known predictors for screw cutout, but the reliability of these measurements is unknown. We investigated the reliability of the tip apex distance measurement, the Cleveland femoral head dividing system, the three-grade classification system of Baumgaertner for fracture reduction, and the AO classification system as predictors for screw cutout. METHODS:All patients with an intertrochanteric hip fracture who were managed with either a dynamic hip screw or a gamma nail between January 2007 and June 2010 were evaluated from our hip trauma database. RESULTS:The tip apex distance measurement was reliable and patients with device cutout had a significantly higher tip apex distance. The agreement between observers with regard to screw position and fracture reduction was moderately reliable. After adjustment for tip apex distance and screw position, A3 fractures were at more risk of cutout compared with A1 fractures. Poor fracture reduction was significantly related with a higher incidence of cutout in univariate analysis, but not in multivariate analysis. Central-inferior and anterior-inferior positions, after adjustment for tip apex distance and screw position, were significantly protective against cutout. CONCLUSION:To decrease probable risks of cutout, the tip apex distance needs to stay small or the screw needs to be placed central-inferiorly or anterior-inferiorly. LEVEL OF EVIDENCE:Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.