The muscle release operation has been performed on 17 patients of Perthes' disease, and the results were followed up for ten years in regard to clinical and radiological aspects on 10 cases. Following are the conclusions based on this study.
1. No clinical complication has been observed except in one case in which joint pain and fatigability of the lower extremities were complained.
2. Radiological examinations disclosed the increase of femoral neck-shaft angle, elongation of the femoral neck and deformity of the femoral head in some cases, ascribable to the release of the trochanter major.
3. The trochanter major developed to the normal size in its new position.
4. There were found deformity of the trochanter minor in a few cases as a probable result of the release of the iliopsoas muscle.
5. It is still an open question whether this procedure is effective or ineffective as a treatment of Perthes' disease.