[Growth disturbance of the acetabulum by damage to the triradiate cartilage of rabbits].

We made the following two experiments to know how the disturbed triradiate cartilage influences the growth of the innominate bone, particularly that of the acetabulum. Experiment 1: Damage to the anterior and posterior flanges of the triradiate cartilage. Experiment 2: Damage to the structures adjacent to the triradiate cartilage by drilling. As a result of these experiments, in Experiment 1 acetabular dysplasia and thickening of the inner wall of the acetabulum as reported in the past were seen and thickening of the outer cortex of the acetabular edge, irregular arrangement, decreases in number of hypertropic cells in growth plate, diminishing of bone formation, irregular hypertrophies of the trabecula were also noted in the whole acetabulum histologically. In Experiment 2, only the thickening of the inner wall of the acetabulum was seen. As described above the anterior and posterior flanges of the triradiate cartilage participate in acetabular growth and damaging makes the acetabulum small in size. While the femoral head grows normally, incongruity between the two occurs, so dislocation of the femoral head, acetabular dysplasia and thickening of the inner wall of the acetabulum are secondarily produced by the damage of articular cartilage or growth plate.