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Pediatr Radiol (2008) 38 (Suppl 2):S246S250 DOI 10.1007/s00247-008-0775-3
REVIEW
Musculoskeletal imaging: evaluation of congenital anomalies
Tal Laor
# Springer-Verlag 2008
Congenital anomalies of the skeletal system often result in abnormalities of limb size, configuration, or segmentation. Frequently, these deformities are associated with soft tissue abnormalities [1, 2]. Soft tissue abnormalities rarely are the only finding. This session will review several congenital anomalies that result in a small limb, abnormal segmentation, and miscellaneous conditions that affect the normal configuration of the appendicular skeleton.
Small limbs
The classification system of Frantz and ORahilly [3]is the basis for the most commonly used descriptions of congenital malformations. The deficient part defines the malformation. For example, tibial hemimelia is characterized by a deficient tibia. The following terms are used to describe congenital malformations, illustrated in Fig. 1.
Terminal: the deformity extends to the end of the extremity (e.g. involves forearm and hand)
Intercalary: the portion of limb distal to the deformity is normal (e.g. abnormal forearm with a normal hand)
Transverse: both sides are affected (e.g. both tibia and fibula)
Longitudinal or paraxial:
one side is affected (e.g. fibular side only)
Preaxial: affecting the radial or tibial side Postaxial: affecting the ulnar or fibular side
The most commonly affected long bones are the fibula, radius, femur, ulna, humerus, and tibia. Although deficiency of one bone usually is dominant, the anomaly often affects the entire limb.
Congenitally short femur
This deformity ranges from mild hypoplasia to complete absence of the femur [4]. A congenitally short femur is characterized by medial cortical thickening and antero-lateral bowing. The knee joint is lax and both tibial and femoral condyles may be flattened [5]. However, the hip joint is stable, differentiating this deficiency from proximal femoral focal deficiency [6].
Proximal femoral focal deficiency (PFFD)
Like a congenitally short femur, PFFD ranges from mild shortening to severe deficiency of the femur and dysplasia of the ipsilateral acetabulum [7]. Up to 15% of affected children have bilateral abnormalities [5]. This disorder presents as a short extremity in infancy (Fig. 2). The dysplasia of the ipsilateral acetabulum mirrors the extent of the deformity of the proximal femur [8]. PFFD also is associated with deformities of the remaining ipsilateral limb, including fibular hemimelia (in >50% of affected children), shortened...