Soft tissue anatomy of proximal femoral focal deficiency.

The soft tissue anatomy of Aitken types A, B, C, and D proximal femoral focal deficiency (PFFD) was examined by magnetic resonance imaging (MRI). A characteristic pattern of soft tissue abnormalities is described. All muscles were present, but most were smaller than their normal counterparts. The exception was the obturator externus muscle, which was elongated and remained muscular almost up to its insertion. In type A PFFD, it is straight; in types B, C, and D PFFD, it is L-shaped. The sartorius is hypertrophied.