ObjectiveTo investigate the method to measure the tip-apex distance (TAD) in treatment of femoral intertrochanteric fracture with proximal femoral nail antirotation (PFNA). MethodsBetween March 2008 and March 2011, 35 patients with femoral intertrochanteric fracture underwent closed reduction and internal fixation with PFNA, which were all closed fractures. There were 14 males and 21 females with an average age of 72.3 years (range, 48-88 years). According to Evans classification, 1 case belonged to type III, 27 cases to type IV, and 7 cases to type V. The time between injury and operation was 2-7 days (mean, 4.3 days). The TAD was measured according to relationship between tip of helical blade and the center point of femoral head radius during operation, and according to X-ray films after operation. ResultsPrimary healing of incision was obtained in all cases, and no infection or deep venous thrombosis occurred. At 2 days after operation, the X-ray films showed TAD was 18-24 mm (mean, 22.6 mm). Thirty-two cases were followed up 10-22 months (mean, 16 months). All fractures healed, with a mean healing time of 7.6 months (range, 6-10 months). The patients could walk without stick at 11-16 weeks (mean, 13 weeks). Pulmonary infection occurred in 1 case at 5 days after operation; no breakage of femoral nail or cut-out helical blade from femoral head was observed. At 10 months after operation, the Parker hip scores were 9 in 23 cases, 8 in 4 cases, 7 in 3 cases, and 5 in 2 cases, with a mean score of 8.44. ConclusionIt is easy to control the TAD in treatment of femoral intertrochanteric fracture with PFNA with an simple method and important to prevent breakage and cut-out helical blade from the femoral head.