RESUMEN
OBJECTIVES: This study was conducted to verify the effectiveness of Anterior Support Screw (AS2) for unstable femoral trochanteric fractures. DESIGN: A multicenter, prospective, randomized controlled trial SETTING: This study was conducted across 15 academic medical centers in Japan PATIENTS/PARTICIPANTS: We enrolled 240 cases of femoral trochanteric fractures with posterior crushing and intramedullary displacement of proximal bone fragments across 15 institutions in Japan. INTERVENTION: All patients were subjected to a reduction in which the anterior cortex was brought into contact. The patients were randomly assigned to the anterior support screw group (AS2 group) and the non-screw group (control group). MAIN OUTCOME MEASUREMENTS: Two computed-tomography (CT) scans were taken immediately after surgery and early postoperative period (day 14-21) to investigate the reduction loss rate of the anterior cortex and sliding distances in the early postoperative period. RESULTS: The reduction loss rate was 4.5 % in the AS2 group and 16.8 % in the control group, indicating a significantly lower reduction loss rate in the AS2 group (p = 0.003). The average sliding distance was 1.8 mm in the AS2 group and 2.8 mm in the control group, indicating a significantly shorter sliding distance in the AS2 group (p < 0.0001). CONCLUSION: Adding a screw in front of the intramedullary nail significantly reduces reduction loss, and maintains anterior bony contact. This study also showed that these screws suppress the sliding distance during the postoperative period. LEVEL OF EVIDENCE: Therapeutic Level I.