Abstract: Objective To assess the value of tip-apex distance(TAD) rule and complications in treatment of unstable intertrochanteric fractures using proximal femoral nail antirotation(PFNA). Methods A study of sixty-two patients with unstable intertrochanteric fractures treated with the PFNAs in our department between January,2014 and November,2016 was performed.Forty patients had been followed up clinically.By means of surgical operation records,radiographs of intraoperative and immediate postoperative and during follow-up periods,we analyzed and evaluated the general results,quality of fractures reduction,the location of the blade within the head was recorded as per the Cleveland Method and tip-apex distance(TAD),implant-related complications.Clinical outcomes were measured with the Oxford hip score. Results There was no patients exhibited postoperative nonunion,the fracture healing time averaged was 3.8 months.The surgery incision length was average (67±18)mm,the mean operative time was (95.1±28.2) min,the mean intraoperative blood loss was (230±148)ml,and the mean hospitalization was (17.8±7.3)d.According to the Oxford hip score,the excellent and good cases accounted for 95%.There were two cases of implant-related failures that the helical blades cut out from the femur heads.The two cut-outs both occurred with tip-apex distance less than 20 mm and tip of helical blades located in Cleveland zone 1 and 5.There were no cut-out in case where the tip-apex distance was between 20-30 mm.Intraoperative femur head fracture and periprosthetic fracture had not occurred. Conclusion The PFNA is an appropriate internal fixation material for the treatment of unstable intertrochanteric fractures.There are a number of cut-outs if we handled the PFNA with TAD less than 20 mm according to the previous rule demonstrated with dynamic hip screw.We suggest and recommend that the tip-apex distance should be revised between 20-30 mm that the cut-out could be effectively avoided.