Classifications (How bad (or good) is it?)

Several classifications have been proposed for PFFD, but the most commonly used one was developed by Dr. George T. Aitken in the early 1960's. Dr. Aitken developed a four class (Class A,B,C,D) classification system based on X-ray results. Class A is the least severe and Class D is the worst case.

It is hard to classify into only four classes a condition that has widely varying degrees of severity with no clear agreement on end points. Perhaps because of its generality, the Aitken Classes appear to be the most widely used and recognized.

Sketch of Aitken subclasses

FIGURE 2 Schematic representation of the four radiographic subclasses
of proximal femoral focal deficiency.

Dr. Dror Payley, a surgeon who specialize in femur lengthening for individuals, uses a [[Paley Classification|more detailed classification system]] that involves the knee.