[Three-dimensional observations of trochanteric fractures of the femur].

In trochanteric fractures of the femur it is difficult to know the exact type and location of fracture lines from conventional radiography. We therefore made a program to reconstruct a three-dimensional image from CT figures and observed closely thirty-six fractures to obtain the following results. These fractures were basically composed of three major fracture lines, the anterior, the posterior and the lateral. The posterior fracture lines were seen in all cases in the same location, a shallow groove located just below the trochanteric fossa and extending to the upper indented portion of the minor trochanter (the paratrochanteric groove). The posterolateral destruction could be observed more frequently than in conventional radiography. From these observations, we have suggested a new anatomical classification based on the contact areas of the proximal and distal fragments classifying trochanteric fractures into five types.