To evaluate the relationship between the bone union and the factors affecting the treatment of a peritrochanteric fracture of the femur with a proximal femoral nail along with the associated complications.

From November 2000 to April 2004, 91 peritrochanteric fractures of the femur were treated with a proximal femoral nail. Three cases were excluded due to sepsis and multiorgan failure. The remaining 88 cases were followed up for mean period of 16.4 months (range, 12-36 months). The mean age was 73 years old (range, 36-94 years old). There were 11 stable fractures and 77 unstable fractures including reverse obliquity fractures and subtrochanteric extension. The relationship between the bone union and the potential associated factors such as reduction status, Singh index, and position of lag screw (tip apex index, TAD) was investigated.

The mean operation time was 60 minutes (range, 42-90 minutes), and the average amount of bleeding was 165 ml (range, 70-250 ml). The mean period for union was 18.4 weeks (range, 12-40 weeks) and 3 cases showed nonunion. The mean Harris Hip Score at the final follow up was 85.3 (range, 23-99). The average union period was 17.0 weeks in the cases with an excellent or fair reduction and 26.7 weeks in those cases with a poor reduction. The average bone union period was 19.2 weeks in cases with a Singh index of 3 or less, and 16.7 weeks in the cases with a Singh index of 4 or more. The average bone union period was 16.8 weeks in the cases with a TAD 25 mm or less, and 20.0 weeks in cases with a TAD more than 25 mm.

The treatment of a peritrochanteric fracture using a proximal femoral nail produced bone union in 96.6% of cases with a 4.5% complication rate. The average bone union period correlated with the reduction status and TAD significantly.