[Experimental study of hypertrophy of the femoral head--with special reference to the effects of the surgical procedure on the hip joint].

This experimental study was performed to clarify how a surgical procedure to the hip joint causes hypertrophy of the femoral head. Young rabbits were used for this experiment. The following results were obtained. In the rabbits with sectioned ligamentum teres, some cases showed complete dislocation on X-ray. The incidence of the hypertrophy of the femoral head was very low in this group. Except in these rabbits with dislocation, the hypertrophy of the femoral head appeared in any group subjected to surgical procedure, and at especially high rates in those subjected to the section of ligamentum teres and/or edge resection of acetabular cartilage. In the cases in which the edge of the acetabular cartilage was resected, and in other cases of surgical procedure as well, acetabular dysplasia often resulted. In these cases the hypertrophy of the femoral head was observed more frequently than in others. In summary, surgical procedure to the hip joint and postoperative abnormal stress to the femoral head contribute to the development of the hypertrophy of the femoral head especially in the cases in which acetabular factors are not negligible.