Comparative study of a novel proximal femoral bionic nail and three conventional cephalomedullary nails for reverse obliquity intertrochanteric fractures: a finite element analysis

The reverse obliquity fracture of the proximal part of the femur is a distinct fracture pattern that is mechanically different from most intertrochanteric fractures. The purpose of this retrospective study was to determine the prevalence of these fractures and the results and complications of different types of internal fixation used in their treatment. Between 1988 and 1998, 2472 consecutive patients with a hip fracture were treated at our Level-One Trauma Center; 1035 of the fractures were classified as intertrochanteric or subtrochanteric. Clinical and radiographic records were retrospectively reviewed, and fifty-five fractures with a reverse obliquity pattern were identified. Forty-nine patients were followed until the fracture united or a revision operation was performed. The duration of clinical follow-up averaged eighteen months (range, three to sixty-seven months), and the duration of radiographic follow-up averaged fifteen months (range, three to sixty months). Fractures were classified with the Orthopaedic Trauma Association scheme. Results were analyzed according to the fracture pattern, type of implant, quality of the reduction, position of the implant, and use of bone graft at the index operation. Function was assessed on the basis of pain, living situation, need for walking aids, need for analgesics, and walking capacity. Thirty-two (68%) of forty-seven hips treated with internal fixation healed without an additional operation. Fifteen (32%) of the forty-seven failed to heal or had a failure of fixation. The failure rate was nine of sixteen for the sliding hip screws, two of fifteen for the blade-plates, three of ten for the dynamic condylar screws, one of three for the cephalomedullary nails, and zero of three for the intramedullary hip screws. Use of the fixed-angle devices (the blade-plate and the dynamic condylar screw) resulted in fewer failures than did use of the sliding hip screw (p = 0.023). Eleven (46%) of twenty-four nonanatomically reduced fractures and four (17%) of twenty-three anatomically reduced fractures had a failure of treatment (p = 0.060). Eleven (26%) of forty-two fractures with an ideally placed implant and four (80%) of five fractures with a non-ideally placed implant had a failure of treatment (p = 0.023). Of the fifteen fractures that failed to heal or had a failure of fixation, five were treated with revision to a calcar-replacement prosthesis, seven were treated with revision open reduction and internal fixation with bone-grafting, and one was treated with bone-grafting without revision of the fixation. Two patients refused additional surgery because they had limited functional demands. The two-year mortality rate was 33%. Functional results were poor, with many patients requiring walking aids and losing the capacity for independent walking and self-care. In this series, reverse obliquity fractures accounted for 2% of all hip fractures and 5% of all intertrochanteric and subtrochanteric fractures. Ninety-five-degree fixed-angle internal fixation devices performed significantly better than did sliding hip screws. Results were also worse for fractures with poor reduction and those with a poorly placed implant.

The proximal femoral nail (PFN) is a recently introduced intramedullary system, designed to improve treatment of unstable trochanteric fractures of the hip. In a multicentre prospective clinical study, the intra-operative use, complications and outcome of treatment using the PFN (n = 211) were compared with those using the gamma nail (GN) (n = 213). The intra-operative blood loss was lower with the PFN (220 ml v 287 ml, p = 0.001). Post-operatively, more lateral protrusion of the hip screws of the PFN (7.6%) was documented, compared with the gamma nail (1.6%, p = 0.02). Most local complications were related to suboptimal reduction of the fracture and/or positioning of the implant. Functional outcome and consolidation were equal for both implants. Generally, the results of treatment of unstable trochanteric fractures were comparable for the PFN and GN. The pitfalls and complications were similar, and mainly surgeon- or fracture-related, rather than implant-related.