Proximal femoral nail for the treatment of reverse obliquity intertrochanteric fractures compared with gamma nail

Background: The reverse obliquity fracture of the proximal femur (AO/OTA 31-A3) is mechanically different from most intertrochanteric fractures. The purpose of this study was to compare the results of proximal femoral nail (PFN) fixation with those of gamma nail (GN) fixation for these fractures. Methods: Between 1993 and 2003, 635 of the fractures were classified as intertrochanteric or subtrochanteric. Clinical and radiographic records were retrospectively reviewed, and 22 fractures with reverse obliquity pattern were identified. The patients were divided into two treatment groups and were followed up for a minimum of 1 year (range, 12-67 months). Eleven patients in group I were treated with the PFN, and 11 patients in group 11 were treated with the GN. The two groups were comparable with regard to demographic and injury variables. The duration of follow-up averaged 18 months (range, 12-67 months). Radiographic changes during the follow-up, clinical outcome, and complications of the PFN group were compared with those of the GN group. Results: Reverse obliquity intertrochanteric fractures accounted for 4.3% of intertrochanteric and subtrochanteric fractures. Bone union time averaged 16.5 weeks in the PFN group and 17.9 weeks in the GN group. Average sliding of lag screw was 2.5 mm in the PFN group and 3.1 mm in the GN group (p = 0.046). Change of the neck-shaft angle was 2.45 degrees in the PFN group and 3.75 degrees in the GN group (p = 0.032). A satisfactory functional outcome was found in eight patients in the PFN group and also in eight patients in the GN group. There was one osteonecrosis of femoral head in the PFN group. There was one cutting out of lag screw, one nonunion, and one varus deformity in the GN group. Conclusion: There was no difference in clinical outcome between the PFN and GN groups. However, the PFN demonstrated better results biomechanically than the GN did in terms of less sliding of lag screw, less change of neckshaft angle, and less complications for the treatment of reverse obliquity intertrochanteric fractures.