Clinical History
Parents of a 6 month old child presented with complaint of left lower limb shortening in the baby since birth. There was no history of trauma. Perinatal history was unremarkable. Delivery was uncomplicated, vaginal. Older sibling of the child had no similar complaints.
Imaging Findings
X-ray AP view of bilateral lower limbs revealed a significantly short left femur as compared to the normal right femur. Acetabular fossa flattening was also demonstrated on the left side. Contralateral fibular hemimelia was also noted. Significant beaking of the bilateral tibial metaphyses and varus deformity of the shafts was also present. The tarsals and metatarsals appeared normal. The epiphyses in general were normally ossified. The X-rays for upper limbs were unremarkable.
Discussion
Proximal femoral focal deficiency (PFFD) is a rare osseous congenital developmental defect of the proximal femur. The defect is deficiency of femur, focally involving its proximal segment. This entity does not include total femoral agenesis. In the majority of the cases unilateral limb is affected. Bilateral involvement is noted in 15-30% affected children. The reported incidence of PFFD is 1:50, 000. [1]
Key hypotheses postulated are [2]:
1. Nutritional deficiency during cell division (4 to 6 weeks of ovulation).
2. Mesenchymal tissue damage by local vascular mechanism.
3. Gestational femoral compression during diaphyseal ossification.
It is noteworthy that familial predilection has not been recognised.
PFFD manifests itself at birth. Classically femur is shortened with resultant abduction and external rotation of the involved limb. Flexion contractures of the hip and knee hypoplasia have also been reported. Common associations include fibular hemimelia, coxa valga, clubfoot, cleft palate, spine and cardiovascular anomalies.
Radiographic assessment is necessary for diagnosing associated anomalies and staging. Aitken's Classification is widely accepted [2]:
Class A: Least severe form. Femoral head is present which is attached to the shaft by a cartilaginous neck that ossifies with age. Femoral segment is short. Coxa vara may be present.
Class B: Femoral head is present. Acetabulum is moderately dysplastic. Absence of osseous connection between the femoral head and shaft.
Class C: Femoral head is absent. Acetabulum is severely dysplastic. Femoral segment is stunted with a tapered end.
Class D: Most severe type. Absence of both the acetabulum and proximal femur. Femoral segment is deformed.
Role of MRI and contrast arthrography [3]:
Usually X-rays help in establishing the diagnosis of PFFD, however, the cartilaginous component needs meticulous assessment from surgical point of view. GRE sequences are a must to look for the cartilaginous connection. Reformatted oblique images may also be required. Any associated coxa vara can also be evaluated. Arthrography establishes with certainty the presence or absence of femoral head.
The goal of therapy is to provide adequate mobilisation. The treatment is individualised based on the severity of the defect. Treatment includes limb lengthening or iliofemoral fusion in Class A and B while Van Nes osteotomy and amputation may be required in severe cases.
Differential Diagnosis List
Proximal femoral focal deficiency
Congenital coxa vara
Femoral facial syndrome
Final Diagnosis
Proximal femoral focal deficiency
