88 Proximal Focal Femoral Deficiency

Clinical Presentation

A 3-year-old female presents with leg-length discrepancy (LLD).

Figure 88A

Radiologic Findings

A frontal view of the pelvis demonstrates shortening with proximal deformity of the left femur (Fig. 88A). A small, left femoral head epiphyseal ossification center is present within a dysplastic acetabulum, and this epiphysis shows no bony continuity with the superolaterally displaced femoral shaft. The proximal end of the ossified femoral shaft is irregular with bone inhomogeneity and sclerosis.

Diagnosis

Proximal focal femoral deficiency (PFFD)

Differential Diagnosis

Radiographically: infantile coxa vara (This entity has a femoral diaphysis of normal length.)
Femoral hypoplasia
Salter injury of the proximal femoral physis
Clinically: developmental hip dysplasia and hip dislocation can mimic

Discussion

Background

PFFD, also known as longitudinal deficiency of the femur, is defined as a deficiency of iliofemoral articulation associated with limb malrotation and leg-length discrepancy (LLD). This rare anomaly (incidence 1 in 52,000) presents as a spectrum of defects ranging from mild femoral hypoplasia with varus bowing to complete absence of the proximal femur and acetabulum. Most observers consider PFFD as a sporadic condition; however, several hereditary case reports have been reported. Associated anomalies are seen in —65% of patients, the most common being ipsilateral fibular hemimelia, which is seen in 50%. Numerous hip, knee, ankle, and foot anomalies have been described, including abnormalities of the contralateral extremity in 25% and bilateral involvement in 15%.

Etiology

Given the wide spectrum of deformities, it is unlikely that there is a single etiologic factor producing PFFD. A developmental insult between 4 and 6 weeks’ gestation is suspected with anoxia, ischemia, trauma, infection, irradiation, or thermal injury all proposed as possible agents. Thalidomide is the only agent proven to cause PFFD.