Clinical and radiological outcome of the Chimaera short nailing system in inter- and subtrochanteric fractures.

Abstract

cephalomedullary devices are popular treatment for femoral intertrochanteric or subtrochanteric fractures. Various complications include post-surgical lateral thigh pain and cut-out. To prevent those complications, a new concept cephalomedullary device system was designed (Chimaera, Orthofix®). This study aimed to evaluate the clinical and radiological outcomes in patients with femoral intertrochanteric or subtrochanteric fractures treated with the proximal femoral cephalomedullary device system. A prospective cohort study involved consecutive patients with Arbeitsgemeinschaft für Osteosynthesefragen/ Orthopaedic Trauma Association type 31-A1, 2, 3 fractures treated with the Chimaera short cephalomedullary device system from October 2016 to September 2017 at our level 1 trauma center. The Parker and Palmer mobility score and Jensen social function scores and post-surgical lateral thigh pain were assessed at 3 months post-operatively and compared to before surgery. Radiologic assessment consisted of controlling the position of the cephalic screw by using the tip-apex distance (TAD) and Cleveland zone as well as union and cut-out rates. We included 99 patients (79 women; 100 hips; one bilateral fracture 3 months after a first trochanteric fracture) with a mean follow-up of 2 years. The Parker and Palmer mobility score decreased by 22% at 3 months post-operatively as compared with the pre-fracture score (42/99 patients showed a return to their pre-injury level). The Jensen social function score increased by 16.5% at 3 months post-operatively as compared with the pre-fracture score (68/99 patients showed a return to their pre-injury level). No major intra-operative complication was recorded. Nine TAD scores were > 25mm. The mean TAD was 16.5mm (range 5-36), and the lag screw position was well positioned in most (95%) hips according to Cleveland zones. Three patients required revision surgery (one for cut-out of the lag screw, one for hip osteoarthritis and one for gluteus medius insufficiency). All patients but the one with the cut-out showed fracture union. The Chimaera short cephalomedullary device exhibited good mid-term functional and radiological outcomes.