Acetabular remodelling after reduction in developmental dysplasia of the hip.

defining the femoral head and the acetabulum. The differentiation of the primitive chondroblasts leads to the formation of the femur, which is in the shape of a club. The anlagen of the ilium, ischium, and pubis develops into a disc-shaped mass. At the age of 11 weeks, the femoral head is fully formed with a spherical configuration, a short neck, and a primitive greater trochanter. 8 With continuous development of the labrum, the femoral head becomes deeply seated in the acetabulum and is held by the surface tension of the synovial fluid. The postnatal acetabular cartilage complex is a unit that is triradiate medially and cup-shaped laterally, interposing between the ilium, ischium, and pubis. This complex is composed of the epiphyseal growth plate cartilage adjacent to these bones, the articular cartilage around the acetabular cavity and, for the most part, hyaline cartilage. The interstitial growth within the triradiate part of the cartilage complex causes the hip socket to expand during growth, and the concavity of the acetabulum develops in response to the presence of the spherical femoral head. 9,10 At puberty, the depth of the acetabulum is further increased by the development of 3 secondary centres of ossification in the hyaline cartilage surrounding the acetabular cartilage. These centres are homologous with other epiphysis in the skeleton. As the acetabulum enlarges, a balance between the growth of the acetabular and triradiate cartilage and that of the adjacent bone induces normal depth of acetabulum. 9 In DDH, this balance may be at risk. In these patients, the degree of acetabular malformation at birth ranges from mild to severe. 10 A ridge in the ischial and Normal development of the hip joint requires the formation of a balanced and harmonious relationship between the growth of the acetabular and triradiate cartilages and the femoral head. 1,2 Developmental dysplasia of the hip (DDH) is a specific condition, in which the harmonious relationship is shattered. The most important concept in the management of DDH is the reduction of the femoral head into the true acetabulum by closed or open reduction to restore this relationship. 3 It is generally assumed that following a stable reduction, various components of the abnormal joint in infancy will develop satisfactorily into a normal joint. 4–6 Accordingly, every effort is made to reduce the dislocation as soon as possible for the development of a normal hip joint. Because of the maximum growth …