Distal Femoral Focal Deficiency

Abstract

Distal femoral focal deficiency is an extremely rare type of congenital femoral deficiency that comprises hypoplasia of the distal femur, with a normally developed hip. We represent a unique case of distal femoral hypoplasia and deficiency of knee extensors, childhood follow-up and final treatment with exarticulation, and a comparison with previous literature. Congenital femoral deficiency (CFD) is a rare congenital anomaly with a reported incidence of 1:50,000 births. [1][2][3] CFD consists all the femoral deficiencies from mild focal hypoplasia to severe deformity. 4 Most of the patients with CFD have proximal focal femoral deficiency (PFFD). Distal femoral focal deficiency (DFFD) is a type of deficiency that encompasses hypoplasia of the distal femur, with a normally developed hip. To the best of the authors' knowledge, it has been described in English literature in only three case reports previously. [5][6][7] Distal femoral focal deficiencies have been previously represented in Pappas and Paley classification schemes for congenital femoral deficiencies. 3,8 Distal deficiencies are classified as Pappas type IX and/or Paley type 4. Taylor et al. also proposed a separate classification scheme for DFFD, presenting types A, B, and C based on the Aitken 9 classification. Type A has an irregular distal femoral epiphysis with a bony connection between femoral components. The femur may be shortened. In type B, the distal epiphysis is present, but there is no osseous connection between the diaphysis and the distal epiphysis. In addition, the femoral length is shortened. In type C deficiency, the epiphysis is absent and the femoral segment is shortened (Figure 1). 7 We represent a case of DFFD and combined deficiency of anterior tight muscles and comparison with the previous reports.