Differentiating Nutrient Artery Canals of the Femur versus Fracture Lines in Patients with Total Hip Arthroplasty on Plain Radiographs

Background: Nutrient artery canals of the femur are often visible on plain radiographs as radiolucent lines which may mimic fracture lines. The purpose of this study was to distinguish nutrient artery canals from fracture lines on plain radiographs. Materials and Methods: Ninety-three patients (102 hips) with an average age of 65.6 years were included in the study. We retrospectively analyzed nutrient artery canals of the femur on pre and postoperative anteroposterior (AP) and cross-table lateral (CTL) hip radiographs in patients with cementless total hip arthroplasty. The shape, number, location, direction of obliquity, length of nutrient artery canal, and the distance between the tip of the greater trochanter and the proximal end of the nutrient artery canal were measured. Results: Nutrient artery canals were determined in 54 hips (53.0%) on preoperative radiographs. The numbers of nutrient artery canals were entirely found to be one for each hip. The nutrient artery canals of the femur were the most frequently seen in the cortex on CTL radiographs with 32 hips (31.4%), whereas nutrient artery canals were not seen at all in the cortex on AP radiographs. All nutrient artery canals in the cortex on CTL radiographs coursed upward obliquely. Comparing to fracture lines, nutrient artery canals show less radiolucency, smaller diameter, and blunted ends in both the cortex and medullary cavity, show sclerotic walls in the cortex and have the less straight course in the medullary cavity. Conclusions: Based on the results of this study, there are clearly distinguishable differences between nutrient artery canals of the femur and fracture lines on plain radiographs.