The inverse relationship between proximal femoral fracture incidence and hip osteoarthritis remains controversial. However, femoral neck fractures rarely occur in patients with hip osteoarthritis, suggesting a protective effect of osteoarthritis. We sought to determine if the severity of osteoarthritis influenced fracture type. We examined the radiographs of 190 consecutive patients treated at our institution after hip trauma. They were divided into three groups according to the outcome of the trauma: femoral neck fracture; trochanteric fracture; and no fracture. We then analysed the severity of osteoarthritis within these groups.
No relationship between the grade of hip osteoarthritis and the presence of a proximal femoral fracture was found. However, the grade of osteoarthritis was related both to the outcome of the trauma (p<0.0001) and to the location of the fracture (p<0.0001). Patients with osteoarthritis of the hip had a three-fold increased likelihood of trochanteric fracture compared to femoral neck fracture. Osteoarthritis does not protect against proximal femoral fractures, but strongly affects the location of the fracture in the proximal femur, increasing the possibility of a trochanteric location.