What is Hip Dysplasia, and Why Are Some Cases Very Mild, While Others Are Quite Severe?

Congenital hip dysplasia describes a multitude of conditions. Some are very mild and may not even be noticed until adulthood. In other cases, the deformities are so severe that the child is unable to weight-bear without surgical intervention and cannot learn to walk as a toddler. How can one term, hip dysplasia, describe such a huge range of hip deformities? Why are some people only mildly affected by this condition, while others are severely disabled?

First, let’s start with some background knowledge. The hip is a ball-and-socket joint. The “ball” refers to the femoral head. The “socket” refers to the acetabulum which is a part of the pelvis.

In some cases, the femoral head is mis-shapened or at the wrong angle to fit into the socket (the acetabulum.) In some cases, the acetabulum itself is just too shallow to hold the “ball” (femoral head) or it is in completely the wrong location on the pelvis (too high or too low.) Sometimes, both the femoral head and the acetabulum are deformed or otherwise unusable.

Congenital hip dysplasia occurs more often in girls than in boys. (It is eight times more likely to occur in girls.) There is a genetic component to hip dysplasia. Most often, hip dysplasia occurs in one hip. For reasons no one completely understands, it occurs in the left hip more often than in the right hip. When you have dysplasia in only one hip, it is called unilateral hip dysplasia. Sometimes, much less often, it occurs in both hips, and that is called bilateral hip dysplasia.

Congenital simply means it is present from birth. This is misleading, because when babies are born, their hips are not fully finished developing. For this reason, this condition is sometimes called developmental hip dysplasia, because it happens as the hip develops.

Congenital hip dysplasia cannot be detected prior to birth. In the US, each baby is check at the hospital for hip dysplasia at birth, but it often goes undetected because the hips are not fully developed. Babies with family histories of hip dysplasia, as well as those who are breech births, or born to mothers with low amniotic fluids, need to be rechecked as their hips develop. Catching this condition early is key in a positive outcome or recovery.

Sometimes, hip dysplasia can occur later in childhood. This is typically caused by Legg-Perthes disease (also called Legg-Calve-Perthes disease.) This disease cuts off some of the blood supply to the femoral head, causing it to deform and lose its round shape. The blood supply eventually returns, but at that point, the damage is done.

If hip dysplasia is caught early, during the first few months, and if it is mild, a device such as a Pavlik Harness can help in reshaping the joint so it will be more functional as the child grows. A Pavlik Harness can only be used on babies younger than about 8 months. It works best on very young babies. It is worn for 6-12 weeks while the baby’s joints are developing. If this approach fails, if the child is too old when the dysplasia is discovered, or if the dysplasia is too severe, then the next step is often a femoral or acetabular osteotomy (or both.)

An osteotomy is when a surgeon cuts and reshapes bone to make it more functional. The bone may be shortened, lengthened, or the angle can be changed to cause realignment. When it comes to hips, there are two basic types of osteotomies, a femoral osteotomy (FO) and an acetabular osteotomy (AO).

In a femoral osteotomy, the ball portion of the hip socket can be reshaped to make it more round, the femoral neck can be shortened or lengthened to make it fit into the socket better, or the angle of the femoral neck and head can be changed. In an acetabular osteotomy, the socket portion of the hip joint can be made deeper, it can be increased, or a section of the pelvis can be cut out, turned, and pinned into place to make better contact with the femoral head.

For most osteotomy procedures, pins and plates are used. Children are placed in body casts after the surgery to assure they do not weigh-bear or change position during the recovery time. Most of the time, another surgery is performed afterwards to go back in and remove the pins and plates after the bone has healed.

There are many types of osteotomies, depending on the deformity that is present. Sometimes, there are multiple deformities causing the hip to not function properly. In extreme cases, more than one osteotomy per side may be required, leading to multiple surgical procedures.

You may ask, why not just do a hip replacement? You can’t do a hip replacement on a child because their bones are still growing, and replacements do not grow. For this reason, they are not an option for growing children. For many, the growth plates do not seal until around age twenty, and hip replacements are not an option until after the growth plate seal.

In young adults, in their twenties and early thirties, if no osteoarthritis has set in, a hip preserving surgery called a periacetabular osteotomy (PAO) is often recommended. Recovery time is longer than for a hip replacement, but the results are often remarkable. This type of procedure is called hip preservation, and preserving the natural bone is almost always preferable to replacing it with implants. People who get a PAO often have to have total hip replacements later in life.

You may ask why not simply give a total hip replacement (THR) as soon as the person’s growth plates have sealed? The reason is very simple. While hip replacements have advanced so much in the past decades, they still only have a life expectancy of 10-15 years. Then, they wear-out, and have to be fixed. When you fix a hip replacement, it is called a hip revision.

Revisions can be as basic as replacing the liner in the “socket” part, or as complex as removing the “stem” portion (the long spike part that goes into the femur) and replacing it, which often requires bone grafts and a much longer recovery time. Each revision is more difficult and more involved than the original hip replacement, and often, each time a revision is done, the person has less bone to work with, requiring bone grafts, and other metal parts (such as screws and bolts) to hold the prosthesis in place.

The outcome for people with hip dysplasia vary a great deal. Those with mild dysplasia and early intervention tend to do well. They often need to limit some activities, such as contact sports and high-impact activities, but are able to maintain a fairly normal lifestyle. Differences in leg length and hip height often leave a tell-tale limp.

Those with more severe deformities and multiple surgical procedures tend to have much more restricted outcomes. People with more severe deformities and multiple surgical repairs tend to suffer from diminished range-of-motion, weakened muscles, muscle atrophy, and very weak hip flexors and hip extensors (glutes), which greatly restrict their walking and standing ability. In these cases, physical activity is often restricted to walking, swimming, and no-impact exercises.

The last part can be very touchy to talk about. Weight has a huge importance in continued hip health. The plain truth is that the more you weigh, the more wear-and-tear you put on your hips. However, people with restricted motion and who use treatments like steroid therapy (a common treatment for pain and inflammation in hip patients) often lead to serious weight gain. It is very common for an orthopedic surgeon to insist a patient lose weight prior to hip preservation surgery or hip replacement surgery.

The reason for this is that these procedures have a much better chance of working if the patient is not obese. Recovery statistics for those who are morbidly obese are not good. Many surgeons will not even consider hip surgery on a patient with a BMI of greater than 35, with most surgeons preferring a BMI of less than 30. (Different doctors have different preferences.) For those whose BMI is greater, weight loss has to take place first – oftentimes leading to bariatric surgery or the use of rapid weight loss techniques such as medically-monitored liquid diets with extreme caloric-consumption controls.

It is not uncommon for surgeons to tell patients “come back when you’ve lost 50, 75, or 100 pounds.” Hearing that you are “too fat” for hip surgery is a very difficult thing to hear, especially when osteoarthritis and hip pain limit your mobility, reduces your exercise options, and some treatments (such as steroid therapy) can cause weight gain. Many orthopedic surgeons refuse to do surgery on those who are obese or morbidly obese. The prognosis is not as good for people who are obese, and the chance for complications is greatly increased. Co-morbidities of those who are obese, such as diabetes, high cholesterol, high blood pressure, and heart disease add to the risks, as well. Sometimes, bariatric intervention, such as a gastric bypass or gastric sleeve have to be considered.

Early detection and treatment improves the life experiences of people with hip dysplasia. Surgical advances have increased the likelihood of normal mobility, and have decreased pain and range-of-motion limitations. The severity and location of hip deformities, the age when receiving initial treatment, ongoing treatment as the person ages, and medical advances all play a part in the recovery potential for people with hip dysplasia.

I hope you’ll take a moment to leave a comment regarding your life journey with hip dysplasia. This can be a very isolating condition, and simply knowing there are others out there with the same condition can make the journey easier for those of us who are traveling this path.