Review Question - QID 220837

This patient has radiographic and clinical evidence of proximal femoral focal deficiency (PFFD), as indicated by a significant limb length discrepancy with a shortened left femur compared to the contralateral side. Congenital absence or laxity of the knee cruciate ligaments is commonly seen with this deformity (Answer 4).

Proximal femoral focal deficiency is a subset of congenital femoral deficiencies that is characterized by a globally small femur with varying degrees of proximal femoral and acetabular deformities. Proximal femoral deformity is a hallmark of this condition. The proximal femur can be hypoplastic, have evidence of a pseudoarthrosis between the head and shaft of the femur, and in some cases, can be fused to the acetabulum. There is often a varying degree of varus present in the femoral neck as well. The exact etiology of this condition is unknown, and it is often sporadic. Other clinical features that can be present in these patients include fibular hemimelia, acetabular dysplasia, a “ball-in-socket” ankle joint, and midfoot abnormalities. Many patients also present with knee abnormalities to include deficient or absent cruciate ligaments, underdeveloped tibial spines, and knee flexion contractures. A knee ligamentous exam is critical, as knee instability can complicate lengthening procedures if not addressed.

Nossov et al. reviewed congenital femoral deficiency, focusing on the clinical manifestations and management principles. In particular, they highlight the importance of a global evaluation of the lower extremity, including the knee, when evaluating patients with PFFD, as additional deformities are often present. They also outline treatment strategies to address deformity and limb length discrepancy.

Sanpera et al. conducted a case series of 24 patients with PFFD, focusing on the incidence of knee laxity within this population. Overall, they found varying degrees of knee laxity (as measured by the Lachman and anterior drawer tests), with only 7 patients demonstrating increased laxity with the Lachman maneuver. Of the 17 patients with a negative Lachman, 9 did have increased translation with the anterior drawer test. The authors concluded that knee laxity was common in patients with PFFD, though it presents along a spectrum of severity. In patients who are planning on undergoing limb lengthening with evidence of knee laxity, an MRI of the knee should be considered to evaluate the integrity of the cruciates.

Figure A demonstrates the full-length lower extremity radiographs of a patient with PFFD. Note the shortened left femur relative to the right side. Figure B is a clinical image of a child with PFFD demonstrating significant limb length discrepancy.

Incorrect Answers:
Answer 1: Clubfoot is not associated with congenital femoral deficiencies
Answer 2: Café-au-lait spots are present in other systemic disorders, such as neurofibromatosis or McCune-Albright, but are not present in patients with PFFD
Answer 3: This can be seen in patients with Turner’s syndrome
Answer 5: This describes the deformity seen in Sprengel’s deformity