Hip dysplasia is the medical term for a hip socket that doesn't fully cover the ball portion of the upper thighbone. This allows the hip joint to become partially or completely dislocated. Most people with hip dysplasia are born with the condition.

Doctors will check your baby for signs of hip dysplasia shortly after birth and during well-baby visits. If hip dysplasia is diagnosed in early infancy, a soft brace can usually correct the problem.

Milder cases of hip dysplasia might not start causing symptoms until a person is a teenager or young adult. Hip dysplasia can damage the cartilage lining the joint, and it can also hurt the soft cartilage (labrum) that rims the socket portion of the hip joint. This is called a hip labral tear.

In older children and young adults, surgery may be needed to move the bones into the proper positions for smooth joint movement.

Signs and symptoms vary by age group. In infants, you might notice that one leg is longer than the other. Once a child begins walking, a limp may develop. During diaper changes, one hip may be less flexible than the other.

In teenagers and young adults, hip dysplasia can cause painful complications such as osteoarthritis or a hip labral tear. This may cause activity-related groin pain. In some cases, you might experience a sensation of instability in the hip.

At birth, the hip joint is made of soft cartilage that gradually hardens into bone. The ball and socket need to fit together well because they act as molds for each other. If the ball isn't seated firmly into the socket, the socket will not fully form around the ball and will become too shallow.

During the final month before birth, the space within the womb can become so crowded that the ball of the hip joint moves out of its proper position, which results in a shallower socket. Factors that may reduce the amount of space in the womb include:

• First pregnancy
• Large baby
• Breech presentation

Hip dysplasia tends to run in families and is more common in girls. The risk of hip dysplasia is also higher in babies born in the breech position and in babies who are swaddled tightly with the hips and knees straight.

Later in life, hip dysplasia can damage the soft cartilage (labrum) that rims the socket portion of the hip joint. This is called a hip labral tear. Hip dysplasia can also make the joint more likely to develop osteoarthritis. This occurs because of higher contact pressures over a smaller surface of the socket. Over time, this wears away the smooth cartilage on the bones that helps them glide against each other as the joint moves.

During well-baby visits, doctors typically check for hip dysplasia by moving an infant's legs into a variety of positions that help indicate whether the hip joint fits together well.

Mild cases of hip dysplasia can be difficult to diagnose and might not start causing problems until you're a young adult. If your doctor suspects hip dysplasia, he or she might suggest imaging tests, such as X-rays or magnetic resonance imaging (MRI).

Hip dysplasia treatment depends on the age of the affected person and the extent of the hip damage. Infants are usually treated with a soft brace, such as a Pavlik harness, that holds the ball portion of the joint firmly in its socket for several months. This helps the socket mold to the shape of the ball.

The brace doesn't work as well for babies older than 6 months. Instead, the doctor may move the bones into the proper position and then hold them there for several months with a full-body cast. Sometimes surgery is needed to fit the joint together properly.

If the dysplasia is more severe, the position of the hip socket can also be corrected. In a periacetabular (per-e-as-uh-TAB-yoo-lur) osteotomy, the socket is cut free from the pelvis and then repositioned so that it matches up better with the ball.

Hip replacement surgery might be an option for older people whose dysplasia has severely damaged their hips over time, resulting in debilitating arthritis.

You'll probably first bring your concerns to your family doctor. He or she might refer you to an orthopedic surgeon.

What you can do

Before your appointment, you might want to:

• Write down any signs and symptoms you are experiencing, including any that may seem unrelated to the reason for which you scheduled the appointment.
• Make a list of any medications, vitamins or supplements that you're taking.
• Consider taking a family member or friend along. Sometimes it can be difficult to remember all the information provided during an appointment. Someone who accompanies you may remember something that you missed or forgot.
• Request that a copy of previous medical records be forwarded to your current doctor, if you're changing doctors.
• Write down questions to ask the doctor.

Your time with the doctor is limited, so preparing a list of questions can help you make the most of your time together. Some basic questions to ask your doctor include:

• What's the most likely cause of my symptoms?
• What kinds of tests do I need? Do these tests require any special preparation?
• What treatments are available, and which do you recommend?
• What types of side effects can I expect from treatment?
• Are there any alternatives to the primary approach that you're suggesting?
• I have other health conditions. How can I best manage these conditions together?
• Are there any brochures or other printed material that I can take home with me?
• Can you recommend any websites for more information on my condition?

In addition to the questions that you've prepared to ask your doctor, don't hesitate to ask questions during your appointment at any time if you don't understand something.

What to expect from your doctor

Your doctor is likely to ask you a number of questions. Being ready to answer them may reserve time to go over any points you want to spend more time on. Your doctor may ask:

• When did you or your child first begin experiencing symptoms?
• Have your symptoms been continuous or occasional?
• Does anything seem to improve your symptoms?
• What, if anything, appears to worsen your symptoms?
• If you or your child has already been diagnosed with hip dysplasia, when and where was the diagnosis made?