To investigate the results of treatment of unstable reverse oblique intertrochanteric fractures with proximal femoral nail (PFN).

We reviewed the results of 16 cases of AO 31-A3.3 intertrochanteric fracture treated with PFN from September 2000 to February 2004 which could be followed up for more than six months and untill bone union. The mean age was 60.2 years old. We investigated the union time and amount of sliding of two screws (neck screw and anti-rotational hip pin) and complications such as fixation failure and nonunion. Functional results were evaluated by the Parker and Palmer mobility score and Jensen social-function score.

All fractures were united and the mean union time were 6.9 months. The amount of sliding of the neck screws and anti-rotational hip pin was 4.8 mm and 3.8 mm on average in 14 cases, respectively. Fixation failure and excessive migration of the screws occurred in two cases; One case showed so-called Z-effect of two screws (reciprocal movement of two screws) and nonunion. The other case showed proximal migration and cutout of the neck screw. There was one femoral shaft fracture at the nail tip caused by a slip. Eight cases (50%) and eleven cases (68.8%) were fully recovered according to Parker and Palmer mobility score and Jensen social-function score, respectively.

We consider that PFN is a suitable implant for treatment of unstable reverse oblique intertrochanteric fractures. However, the revision of implant design is recommended to prevent the excessive migration of the femoral neck screw and anti-rotational hip pin.