Abstract
1. The examination of fifty-one infants presenting signs of unilateral dysplasia (preluxation) of the hip disclosed the existence of an abduction-contracture in the opposite "normal" hip.
2. The abduction-contracture was not infrequently found in the newborn, but seemed to attract attention mostly between the second and fifth month of life. It was seldom found after the sixth month.
3. The dysplasia in the contralateral hip showed the usual features.
4. The relationship between the degree of abduction-contracture and the degree of dysplasia was a direct one only occasionally; in most cases they seemed unrelated to each other.
5. Observation of these patients showed that the abduction-contracture followed a constant course towards gradual and spontaneous regression. The dysplasia progressed in one of the following directions: spontaneous recovery, rapid or slow recovery with treatment by abduction splint, subluxation, or true dislocation.
6. It is submitted that the coexistence of unilateral dysplasia of the hip and abduction-contracture in the opposite hip is not fortuitous. It is believed that the abduction-contracture determines the development of the dysplasia in the opposite hip through the faulty mechanics caused by "fixed pelvic obliquity."
7. The discovery of unilateral abduction-contracture soon after birth should be a warning that dysplasia may develop in the opposite hip. A careful watch should therefore be kept for signs of abduction-contracture and for the later development of dysplasia.
