Can Views of the Proximal Femur Be Reliably Used to Predict Malrotation After Femoral Nail Insertion? A Cadaver Validation Study.
We investigated the relationship between the size of the lesser trochanter visualized on an AP view of the hip and femoral rotation after femoral shaft fracture fixation. We hypothesized that the amount of the lesser trochanter visualized can accurately detect differences in femoral shaft rotation. Sequential fluoroscopic images of 19 matched pairs of cadaver femora were obtained of the proximal femur at 10° increments of internal and external rotation. The relationship between the percentage of the lesser trochanter and the angle of femoral rotation was assessed by regression analysis. Rotation of the proximal femur follows a relatively linear relationship centered around the neutral rotation position. A 10% change in the lesser trochanter size corresponds to approximately 7° of femoral rotation. The relationship between the size of the lesser trochanter visualized and the degree of femoral rotation after femoral shaft fracture fixation is approximately linear and sensitive to relatively small changes in rotation, making it potentially useful for assessing malrotation after femoral shaft fracture fixation.