What Is Hip Dysplasia?
Hip dysplasia is a condition in which your hip socket doesn't completely cover the ball of one of your thigh bones. Your hip is the biggest ball-and-socket joint in your body.
The ball of your thigh bone (femoral head) fits into the socket of your pelvis to form your hip joint. If your hip is in place the way they should be, the ball rotates freely in the socket and let’s you move.
But if you have dysplasia, your hip joint can easily dislocate and will also wear out faster than normal. Imagine a tire that’s out of balance on a car. The tread on that tire will wear out sooner than it would if it were properly aligned.
Most people who have hip dysplasia are born with it (this is called developmental dysplasia or congenital dislocation of the hip). Doctors usually check for it in newborns, and during each well baby visit until they’re 1 year old.
Symptoms of Hip Dysplasia
The signs and symptoms of hip dysplasia can depend on age. Babies sometimes have one leg that’s longer than the other, and kids might have one hip that’s less flexible than the other or limp when they start walking.
If you’re a teenager or young adult, the first signs you might notice are hip pain or a limp. You might also have “clicking” or “popping” in the joint, but these can all also be symptoms of other hip disorders.
The pain usually comes on when you’re doing physical activities, and it’s typically located in the front of the groin. But you could also have discomfort in the side or back of your hip. It could start out mild and happen occasionally, and over time become more intense and frequent. Half of patients with hip dysplasia also have pain at night.
The pain can cause a mild limp. You might also develop a limp if you have weak muscles, a bone deformity, or limited flexibility in the hip joint. If you have a limp for one of those reasons, you probably won’t feel pain.
Hip Dysplasia Causes and Risk Factors
Hip dysplasia can run in families and it happens more often in girls than boys. It shows up in babies because the hip joint is made of soft cartilage when you’re born. Over time, it hardens into bone.
The ball and socket help mold each other during this time, so if the ball isn’t fitting properly into the socket, the socket may end up too shallow and not form completely over the ball.
There are a few reasons this can happen right before a baby is born:
It’s the mother’s first pregnancy.
The baby is large. Or there is oligohydramnios, a condition in which there is too little amniotic fluid in the sac that the baby has lived in throughout the pregnancy, which limits the baby's movement.
The baby is in the breech position -- meaning the rear, not the head, is toward the birth canal.
All of these things can reduce the amount of space in the womb, which can make things crowded for the baby and move the ball out of its proper position. Swaddling babies with their hips and knees straight can also contribute to the condition.
Hip Dysplasia Diagnosis
Babies:
The doctor will look for hip dysplasia at your baby’s first appointment. They’ll check for it by gently moving her legs around in different positions to see if the joint fits together. If your baby was in a breech position, or your doctor suspects she may have dysplasia, they will probably do an ultrasound in the first 3 months after birth to be sure.
Teens and adults:
For symptoms later in life, your doctor will start with a physical examination looking for:
A tilt to the pelvis
Differences in the length of your legs
Muscle wasting
Limping
They will also check the mobility in your hip and may do something called an impingement test, in which they flex your hip and then twist it toward the middle of your body. If you have hip dysplasia, this should cause a pinching feeling.
If your provider suspects that you have hip dysplasia, they might suggest certain imaging tests. An MRI can give them information about any damage to the cartilage, and an X-ray can show how severe the dysplasia is.
Hip Dysplasia Treatment
Babies:
How hip dysplasia is treated depends on your child’s age and the severity of the condition. Babies diagnosed early can usually wear a soft brace that holds the ball of the joint in the socket for a few months to help mold it into the proper shape. A baby older than 6 months may need a full-body cast or surgical intervention.
Older children and adults:
Surgery is usually the only treatment. If the dysplasia is mild, it can usually be treated arthroscopically, which means the surgeon makes tiny cuts and uses long-handled tools and tiny cameras to fix the problem.
But if the dysplasia is more serious, and a child or young adult is skeletally mature, the surgeon may have to cut the socket free from the pelvis and reposition it so it matches up better with the ball. This surgery is called periacetabular osteotomy. This procedure can help prevent or delay the hip arthritis that can come from the dysplasia.
Hips severely damaged because of dysplasia might need replacement surgery.
Hip Dysplasia Complications
Babies and young children:
Children who are treated with a cast may walk a little later than expected, but should catch up once they are no longer in the cast.
The difference in leg length may not go away.
The hip socket still may not be as deep as it needs to be and require surgery later in life.
Teenagers and young adults:
Hip dysplasia can lead to the development of two painful complications:
Osteoarthritis in the hip joint
A tear in the cartilage that helps keep your hip stable called a labral tear