Cephalomedullary blade cut-ins: a poorly understood phenomenon

Objectives Proximal femoral nail antirotation (PFNA) cut-in is a unique phenomenon seen in pertrochanteric hip fractures treated with the PFNA. Cut-in refers to the superomedial migration of the proximal femoral blade into the femoral head and hip joint. We recognize that cut-in is a completely separate entity from the well-described cut-out failure. This study assesses relevant radiological and patient risks factors for cut-in. Design Retrospective multicenter study looking at patients with pertrochanteric hip fractures managed with the Synthes PFNA Setting Four tertiary hospitals over 7 years. Patients Patients with cut-ins were identified. Outcome measurement The radiological appearance of this mode of failure was assessed and compared to cut-outs. Patient demographics, fracture configuration, time to implant failure (cut-in), bone mineral density, tip–apex distance, neck–shaft angle and position of the tip of the helical blade in the femoral head were collected. Results There was a total of 1027 patients across 4 institutions with 23 patients with cut-in. Average neck–shaft angle was 133 degrees. 16 out of 19 patients had severe osteoporosis with BMD