Treatment of unstable trochanteric hip fractures : A clinical, mechanical and radiographic evaluation of the RAB-plate

Sammanfattning: The problems associated with the management of proximal femoral fractures gain more attention as the elderly population continue to increase. It has been estimated that the total number of hip fractures in the world will increase from 1.7 million per year in 1990 to 6.3 million per year in 2050 (Cooper et al 1992). Operative treatment of these fractures is a challenge for the orthopaedic surgeon mainly due to poor bone quality, which increases the risk of fixation failure.More than 50% of the total number of hip fractures are extracapsular fractures. Mortality, morbidity and costs as a result of trochanteric fracture are higher than those for a cervical fracture. The consequence is increased resource consumption in the national health-care system. The estimated total cost of treatment increase 3-fold in case of a complication. Therefore, a variety of different devices have been designed in order to decrease the ratio of complications. However, in spite of this, the reported ratio of fixation failure continues be high and may reach 25% following treatment of unstable trochanteric fractures. We evaluated a new type of fixation device, the RAB-plate (Rigidity Augmentation Baixauli), for the treatment of unstable trochanteric hip fractures. The RAB-plate is a fixed 120-degree angle blade-plate with a buttress rod.We performed three clinical trials where 391 unstable trochanteric fractures were stabilised with the RAB-plate or a Sliding Hip Screw (SHS). The results showed a statistically significant lower number of complications in fractures stabilised with the RAB-plate.The fatigue resistance of the RAB-plate was evaluated in a cyclic loading test model. The RAB-plate had a statistically significant higher fatigue strength than two different designs of the SHS.Stability of the fixation and modes of failure were radiographically analysed in a series of 218 unstable trochanteric fractures treated with the RAB-plate or the SHS. The RAB-plate provided a more stable fixation especially with regard to maintained postoperative alignment. However, positive predictors for fixation failure e.g.implant position within the femoral head, varus reduction in anteroposterior projection and screw/neck angle deviation in the lateral projection were identical for both devices.Spontaneous femoral neck fracture after removal of the fixation device in healed unstable trochanteric fractures was investigated in a series of 7 patients. Our results indicate that implant-induced osteoporosis (stress protection) is a possible cause of subsequent fracture.Our conclusions are that the RAB-plate is a safe implant for fixation of unstable trochanteric hip fractures and results in lower incidence of complications compared to SHS. Therefore, the RAB can be recommended for fixation of unstable trochanteric fractures.