Relationship between the sphericity of femoral head-acetabulum and the low incidence of primary osteoarthritis of the hip joint in Koreans.

UNLABELLED: I examined the sphericity and the congruity of the femoral head and the acetabulum in 172 Korean fetuses and in 655 Korean adults. I found that Korean fetal acetabuli and femoral heads are spherical and that the proportion of the head contained in the acetabulum remains constant and congruous throughout the fetal life. Adult actabuli and femoral heads are also spherical in both gender and are there are no visible changes in the shape of the acetabuli and the femoral heads with respect to age. No evidence was found that the congruity of the hip joint is a cause of osteoarthritis of the hip joint.

CLINICAL RELEVANCE: Stable hip joints at the time of birth provide an explantation for the low incidence of congenital dislocation of the hip joint in Koreans. The spherical femoral head and acetabulum (congruous hip joint) seem to be a contributing factor to the low incidence of primary osteoarthritis of the hip in Koreans.