Evolution of the angle of obliquity of the femoral diaphysis during growth - Correlations

Numerous studies of the bicondylar angle of the adult femur have been carried out in human anatomy, paleoanthropology and primatology. The aim of this paper is to study the evolution of this angle in relation to age and acquisition of walking in young children. Seventy-seven radiographs of children, ranging from 5 months to 17 years postnatally, and of four dead newborn were analysed. The measurements concern the bicondylar angle (A.O.F.), the collo-diaphyseal angle (A.C.D.), the length of the femoral neck (L.N.) and of the femur (L.F.) and the interacetabular distance (D.I.A.). Some children were x-rayed at different ages, which permits a longitudinal as well cross-sectional study. The results show that there is no sexual dimorphism and that the increase in the angle is closely related to the age of the child. The bicondylar angle starts at 0° at birth and then increases progressively with growth to reach adult values of at least 6°-8° between 4 and 8 years postnatally. In adults, the mean values are between 8° and 11° and the maximum range is between 6° and 14°. The obliquity angle corresponds to an angular remodeling of the femoral diaphysis, which is independant of the growth and shape of the distal femoral epiphysis. The tibio-femoral angle measures the evolution of a physiologic phenomenon, from the load “in varus” to the load “in valgus” of the lower limb. It is linked with the bicondylar angle but is different from it.