Hip dysplasia is a condition where the hip socket doesn’t fully cover the ball of the thighbone, creating an unstable or poorly fitting joint. It can be present at birth, develop during infancy, or go undetected until adulthood. In a normal hip, the socket (acetabulum) forms a deep cup around the top of the femur. In a dysplastic hip, that cup is too shallow, too steep, or misshapen, which means the joint bears weight unevenly and wears down faster over time.
What Happens Inside a Dysplastic Hip
The acetabulum in a dysplastic hip tends to be smaller than normal, with thinner walls at the front and a shape that narrows toward the top rather than forming a round, even cup. Because the socket is shallow, the femoral head sits partially outside of it. This concentrates all the body’s weight onto a small strip of cartilage at the rim of the socket instead of spreading it across the entire surface. Over years, that uneven loading damages the cartilage and the bone beneath it.
In mild cases, the femoral head stays mostly in the socket but shifts slightly out of position (subluxation). In severe cases, particularly those graded as Crowe IV, the femoral head is completely dislocated and sits above the true socket entirely. The bone quality around the socket is often poor in these cases, which makes later surgical correction more complex.
Risk Factors
Girls are significantly more likely to develop hip dysplasia than boys. Other established risk factors include breech positioning during the third trimester (when the baby’s feet or bottom are pointing down), being a firstborn child, having a family history of hip dysplasia, being a twin, and high birth weight. Breech position is particularly important because the baby’s legs are often pushed into an extended, pressed-together position in the womb, which can prevent the socket from developing normally.
How Infants Are Screened
Newborn screening relies on two hands-on tests performed in the first days of life. The Barlow maneuver gently pushes the flexed hip backward to see if the femoral head can be pushed out of the socket, identifying a hip that’s dislocatable. The Ortolani maneuver does the reverse: the examiner gently spreads the baby’s flexed hip open to see if a dislocated femoral head will slide back into place. A “clunk” (not just a click) during either test signals instability. The baby needs to be calm and relaxed for the tests to work properly, and the examiner needs enough experience to tell the difference between a harmless soft-tissue click and the deeper clunk of a shifting joint.
When a physical exam raises concern, ultrasound is the standard imaging tool for infants under about four to six months. The key measurement is the alpha angle, which reflects how much bony coverage the socket provides. An alpha angle above 60 degrees is normal. In newborns under three months, an angle between 50 and 59 degrees is considered “immature” rather than dysplastic, because many hips in this range will mature on their own by 12 weeks. After three months, that same 50 to 59 degree range is classified as true dysplasia and typically requires treatment. Once a child is old enough for the hip bones to be well-ossified (usually around six months), X-ray replaces ultrasound as the primary imaging method.
Symptoms in Adults
Many people with mild hip dysplasia have no symptoms in childhood. The condition often surfaces in the late teens or twenties as a dull, persistent ache in the groin or front of the hip. The pain worsens with activity, especially walking, running, or standing for long periods, and it can occasionally radiate down to the knee.
Because the shallow socket forces the soft-tissue rim (labrum) to absorb forces it wasn’t designed for, the labrum thickens, frays, and eventually tears. More than 90% of people with labral tears report pain in the anterior hip or groin. Mechanical symptoms are common too: clicking is the most frequent complaint, followed by a catching or locking sensation in the joint, or a feeling that the hip might give way. These episodes of sharp pain tend to punctuate a baseline of constant dull discomfort.
What Happens Without Treatment
A 45-year follow-up study of patients with late-detected hip dysplasia illustrates the long-term stakes clearly. Among hips that eventually achieved a normal socket angle (a center-edge angle of 20 degrees or more), only 5% developed osteoarthritis. When residual dysplasia remained but the hip stayed in the socket, 22% developed arthritis. When the hip was subluxated, meaning the femoral head had shifted partially out of the socket, 80% developed osteoarthritis over the follow-up period. The more the socket fails to cover the femoral head, the more certain the cartilage destruction becomes.
Treatment for Infants
The Pavlik harness is the first-line treatment for infants diagnosed in the first six months. It’s a soft brace that holds the baby’s hips in a flexed, outward position, encouraging the socket to deepen as it grows around the femoral head. Success rates range from 80 to 97%, with better outcomes when treatment starts early. The harness is initially worn full-time, then gradually weaned: a few hours off per day at first, then half-days, then nighttime-only use before stopping entirely. The weaning process typically unfolds over several weeks. If the Pavlik harness fails, a rigid brace or a procedure to manually reposition the hip under anesthesia may be needed.
Surgery for Older Children and Adults
When dysplasia is diagnosed in adolescence or young adulthood and the joint cartilage is still in reasonable condition, the gold-standard procedure is a periacetabular osteotomy (PAO). The surgeon cuts the bone around the socket and repositions it to provide better coverage of the femoral head. It’s typically recommended for symptomatic patients younger than 35 whose joints haven’t yet developed significant arthritis.
Recovery is substantial. You’ll use crutches for several weeks and gradually progress through rehabilitation stages, starting with basic exercises lying on your back and building toward standing, kneeling, and eventually single-leg balance work. Even at one year post-surgery, hip strength remains 13 to 34% lower than in people without dysplasia. Full recovery and return to high-level activity can take well over a year. For older adults or those with advanced cartilage loss, total hip replacement becomes the more practical option.
Swaddling and Prevention
You can’t prevent hip dysplasia caused by genetics or breech positioning, but you can avoid making it worse. The International Hip Dysplasia Institute recommends that swaddled babies’ legs should be free to bend up and out at the hips. Wrapping an infant’s legs straight down and pressed tightly together increases the risk of dysplasia and dislocation, because forced extension can loosen the developing joint and damage the soft cartilage of the socket.
The safest approach is to swaddle the upper body snugly while leaving enough room in the blanket or swaddle sack for the hips and knees to stay slightly bent, with the legs able to fall naturally apart. Avoiding sustained hip extension and keeping the legs pressed together during the first few months of life is essential for normal socket development.