Proximal focal femoral deficiency: evaluation by MR imaging

Abstract

Proximal focal femoral deficiency (PFFD) is a rare congenital anomaly characterized by abnormal development of the proximal femur. The most common radiographic classification (Aitken) does not evaluate the cartilaginous and soft-tissue abnormalities. To demonstrate MR findings of PFFD focusing on features not seen with radiographs. Nine MR examinations of the hip and femurs of seven children with PFFD were retrospectively reviewed. Imaging was quantitatively and qualitatively assessed comparing the affected limb to the contralateral limb and age-matched controls. The children were classified via the Aitken classification. All children had at least mild acetabular dysplasia, and one type D patient had no acetabulum. MR demonstrated that 4/6 children had labral hypertrophy with a decreased distance from the greater trochanter to the acetabular rim, suggesting impingement (P<0.05). The proximal femoral physis was abnormal in all cases. The connection between the femoral head and shaft if present was fibrous or fibrocartilaginous. MRI can help in evaluation of PFFD by defining the anatomy. MR demonstrates features of the acetabulum and cartilaginous femoral epiphysis and depicts ligamentous abnormalities of the knee.