Tip Apex Distance of Intramedullary Devices as a Predictor of Cut-Out Failure in Treatment of Peritrochanteric Elderly Hip Fractures

Abstract

BACKGROUND A Tip-Apex Distance (TAD) of greater than 25 mm has been shown to be an accurate predictor of lag screw cutout when Sliding Hip Screws (SHS) are used to treat Peritrochanteric (PT) fractures. The purpose of this study was to determine, which factors, including TAD correlated with successful clinical outcomes of PT hip fractures surgically treated with intramedullary devices. MATERIALS AND METHODS A total of 72 patients were included in this retrospective study. TAD values were radiographically analysed at a mean follow up of 13 months. This was correlated with limited functional status and rate of revision for implant failure or inability to achieve fracture union. Only 62 patients had adequate follow up to fracture union or definitive failure. RESULTS There were 36 intertrochanteric fractures and 26 subtrochanteric fractures. Overall, 5 patients (9.8%) went on to experience lag screw cut out. The average TAD of patients who did not cutout was 18 mm compared to 38 mm for those who did (p=0.012). All patients who cutout had IT fractures. CONCLUSION The percentage of cutouts correlated clinically to both the severity of IT fractures and the TAD. Using a cutoff of 25 mm, there was a statistically significant difference in the incidence of lag screw cutout (p<0.001). As in sliding hip screw, surgeons should strive for a TAD less than 25 mm when using IM devices in the treatment of PT hip fractures to help avoid lag screw cutout .