From a study of thirty-seven patients with spastic cerebral palsy (twelve quadriparetics, twenty-one diparetics, and four hemiparetics), treated by hip-flexor release and other procedures, it was concluded that a hip-flexion deformity is a primary abnormality in all children with spastic cerebral palsy and that this deformity is largely responsible for their characteristic crouching posture and excessive lumbar lordosis. It was also concluded that the unstable posture after hamstring transplantation is secondary to the hip deformity. The myotomy described will reverse this unstable posture. Furthermore, from this experience it seemed clear that until the spastic flexion and internal rotation deformities are released, active and passive abduction will be limited and useful function and progressive development of the abductor muscles cannot occur. In a somewhat similar way function and development of the hip extensor and trunk extensor muscles will also be impaired unless the tight portions of the hip-flexor muscle group have been released.

During this study, by sequentially dividing the different hip-flexor muscles and repeatedly testing the hip-flexion contracture after each myotomy during the operation, it was established that the muscles causing the contracture are the sartorius, tensor fasciae latae, the tight anterior portions of the gluteus medius and minimus, and the rectus femoris.

The short-term results in this small series (length of follow-up, one to four years) indicate that release of the aforementioned muscles early in life (near the age of three years) results in the development of more normal posture, a better gait, and correction of the internal-rotation deformity of the hip. Although other procedures on the hips and knees were at times necessary (including adductor release and a modified Eggers procedure), early hip release appeared to reduce the need for these operations, especially hamstring transplantation.