Femoral shaft medialisation and neck-shaft angle in unstable pertrochanteric femoral fractures.

We analysed the time-dependent mean changes in the femoral neck length, neck-shaft angle and hip offset in a randomised study comprising 48 patients who were treated with the dynamic hip screw (DHS) or the proximal femoral nail (PFN) for an unstable intertrochanteric femoral fracture. As a consequence of fracture compression, the mean post-operative neck length was significantly shorter in patients treated with the DHS. During the first 6 weeks after the operation, a mean decrease of 4.6 degrees was observed in the neck-shaft angle, but there was not a significant difference between the treatment groups. The radiographic measures remained virtually unaffected during the interval from 6 weeks to 4 months in both groups. When the operated hip was compared to the opposite hip, patients who had received the DHS showed significantly greater medialisation of the femoral shaft at 4 months than those treated with the PFN. We thus recommend that unstable intertrochanteric fractures should be initially reduced in a slight valgus position in order to achieve an outcome after healing that is as normal as possible. As a result of differences in operative technique and implant stability, the PFN may be superior to the DHS in retaining the anatomical relations in the hip region in unstable intertrochanteric fractures.