Ankle and foot deformities and malformations in proximal femoral focal deficiency

Abstract

Purpose: To describe foot abnormalities in proximal femoral focal deficiency and their correlation to the severity.

Methods: Eighty-nine extremities in 87 patients were evaluated between 1996 and 2020 clinically and radiologically. Fibula length, ankle shape, tarsal coalitions, and the number of foot rays were recorded. Extremities with proximal femoral focal deficiency were classified according to Pappas and divided into severe (classes II and V), medium severe (classes III and IV), and mild groups (classes VII, VIII, and IX).

Results: The fibula was short in 89% and absent in 11% of cases. An absent fibula occurred mostly in severe class III and only in 4% of mild grades (statistically significant, p = 0.004). The valgus ankle joint prevailed in 82% of cases. Spherical ankle joints (18% of cases) were associated in all cases with a tarsal coalition. Tarsal coalitions occurred in 14.6% and were present in all classes except class IV. Five ray feet were found in 83% of cases, four ray feet were found in 16%, and three ray feet in one extremity. Reduction in the number of foot rays occurred more commonly in association with fibular aplasia (30%).

Conclusions: Abnormalities of the fibula and ankle joint represent a constant part of proximal femoral focal deficiency, whereas tarsal coalition and a reduction of foot rays do not. The severity of foot abnormalities does not correlate to the severity of proximal femoral focal deficiency but does with fibular aplasia.

Keywords: Foot; fibula deficiency; lateral ray deficiency; proximal femoral focal deficiency; subtalar synostosis.

Figure 1.

CT angiography of PFFD type IV left, boy, age 7 years. Pseudarthrosis and shortening of the femur, valgus knee, shortening of the fibula, and reduction of the diameter of the femoral artery are seen. PFFD: proximal femoral focal deficiency; CT: computed tomography.

Figure 2.

Diagram of the distribution of PFFD in relation to Pappas classes. PFFD: proximal femoral focal deficiency.

Figure 3.

Diagram of the fibula length/deficiency in relation to Pappas classes. F short dist.: distal shortening; F short dist. and prox.: both proximal and distal shortening; F short dist.+prox. aplasia: distal shortening and proximal fibular aplasia; fibular aplasia: complete absence of fibula.

Figure 4.

Plain radiographs of ankle joint, A-P view in two extremities with PFFD. Fibular shortening and valgus ankle joint (a) and spherical ankle joint (b) are apparent. PFFD: proximal femoral focal deficiency.

Figure 5.

Diagram of the shape of the ankle joint (valgus, spherical) in relation to Pappas classes.

Figure 6.

Plain radiograph, A-P view of ankle and foot in PFFD Pappas class III right, girl, age 17 years. Valgus shape of the ankle in fibular aplasia. PFFD: proximal femoral focal deficiency.

Figure 7.

Plain radiograph, lateral view of ankle and foot in PFFD Pappas class VII, girl, 15 years. Multiple tarsal coalitions and shortening of the fibula are present. PFFD: proximal femoral focal deficiency.

Figure 8.

Diagram of the tarsal coalitions (yes—present, no—not present) in relation to Pappas classes.

Figure 9.

Plain radiograph, A-P view of the left foot in PFFD Pappas class IV. Reduction of the foot rays (metatarsals), duplication of the fourth toe, and changes in tarsal bones are apparent. PFFD: proximal femoral focal deficiency.

Figure 10.

Diagram of the number of foot rays in relation to Pappas classes.