Fixation of rotationally unstable extracapsular fractures of proximal femur

Abstract

Introduction: It was believed that the fractures of AO types A1.2 and A1.3 are rotationally stable; but, they were found to be unstable when fixed with the dynamic hip screw. Hence we hypothesize that they must be treated as rotationally unstable patterns. Materials and Methods: dynamic hip screw with derotation screw (DHS-DRS) was done in 83 proximal femur fractures of A1, A2, and B2.1 types and followed for 24 months. Immediate assessment of reduction and fixation are found to be accurate. Collapse of fractures assessed after 6 months of surgery. Fractures were classified into 2 groups: Inevitably unstable group (IUG) - A1.1, A2.1, A2.2, A2.3, and B2.1. Potentially unstable group (PUG) - A1.2 and A1.3 and results were statistically analyzed. Results: Reduction achieved in 77 patients was found to be adequate and same goes for the fixation in 71 patients. All fractures healing showed a mean time of 13.5 weeks, and the fracture collapse amounted to an average of 5.8 mm. 66 patients showed equalization of the lower limbs, and 80 patients showed healthy contralateral equalization of hip motion range. One case with AO type A1.2 needed a re-operation. Insignificant differences were found when outcome of IUG and PUG was made. Conclusion: The use of DHS/DRS composite showed restoration and maintenance of the anatomical structure. Differences between the outcomes of IUG and PUG groups were insignificant and creates a reasonable need of classifying AO A1.2 and A1.3 as rotationally unstable types. Keywords: Derotation screw, Proximal femoral fractures, DHS/DRS composite, Basicervical fracture, Dynamic hip screw, Rotational instability, Trochanteric fractures.