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Hip dysplasia (adult)

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What you're feeling¶

Hip dysplasia means the socket of your hip is shallower than it should be, so it does not fully cover the ball at the top of your thigh bone. Many people have this without knowing it, because there may be no pain at all until the hip starts to wear out early.

The most common symptom is a deep ache in the front of your groin, usually on one side. It tends to build up slowly rather than start suddenly. Some people feel it on the outside of the hip instead, and this side pain is often milder and easier to miss. Pain usually gets worse with activity, especially long walks or long periods of standing, and it often comes on later in the day as your hip muscles tire. Resting from activity often settles it.

The ache can also flare when your hip is bent up and turned inwards, for example when you pull a shoe on while seated, crouch down to load a dishwasher, or get into a low car. You might notice a clicking, snapping or popping feeling deep in the groin. That can be a sign the soft rim of cartilage around the socket, called the labrum, is irritated or torn.

Over time the pain can wear you down. You may find yourself cutting back on walks, sport or stairs, and standing still at work or waiting in a queue becomes uncomfortable. Some people develop a slight limp or a waddle, where the hip drops on the other side as you step, because the muscles holding the hip steady are working harder than they should.

If you were diagnosed with hip problems as a child or teenager, or had treatment for a dislocated hip, this may be connected. But many people reach adulthood with no history of hip trouble at all, and the first sign is simply this groin ache that will not settle.

What's actually happening¶

Think of your hip as a ball sitting in a cup. In a healthy hip, the cup wraps well around the ball, so your body weight is spread across a wide, smooth surface. In your hip, the cup is shallower and more upright than it should be, so it covers less of the ball. Your weight then presses down on a much smaller patch of cartilage near the rim of the socket, a bit like walking on the edge of a shoe sole instead of the whole foot. That small patch takes far more pressure than it was built for, and over the years it starts to break down.

The shallow socket also makes the joint loose. The ball can shift slightly within the cup, and the soft rim of cartilage around the socket, called the labrum, has to work overtime to hold things steady. The labrum acts like a rubber gasket that seals the joint, but a shallow socket asks it to do a job it was never designed for. It becomes irritated and can tear, which is where much of your groin ache and clicking comes from. The muscles around the hip also work harder to steady the joint, which is why they tire late in the day and why standing for long stretches becomes uncomfortable.

This condition usually starts before birth or in early childhood, when the socket does not finish forming around the ball. It is more common in girls, and it often runs in families. Some hips are only mildly affected, while others are loose enough that the ball partly slides out of the socket, and a smaller number are fully dislocated. The milder forms often go unnoticed until adulthood, when the overloaded cartilage and labrum finally start to complain. If the extra wear continues unchecked, the joint can develop wear-and-tear arthritis earlier in life than it otherwise would.

What we can do about it¶

Dr Kieran Hirpara, an upper-limb surgeon at Mater Private Hospital Rockhampton, starts with the least invasive options that suit your condition. Patients are generally referred to our clinic by their GP; if a physiotherapist has suggested you see us, you will still need a referral from your GP in order to be eligible for the Medicare rebate. At your first visit we take a history, examine your hip and arrange imaging where needed. X-rays show how well the socket covers the ball. Scans can add detail on the cartilage, the labrum and the shape of the bone.

For a long-standing problem like this, we usually try non-operative care first. Changing how you stay active is a good start. Cutting back on long walks, standing for long stretches or heavy loading can settle the ache, while keeping the hip moving in ways that do not flare it. Physiotherapy aims to strengthen the muscles that hold the hip steady, so they tire less late in the day and the joint moves more smoothly. We usually give this a fair trial over several months before thinking about anything further.

Pain relief can help you keep moving through this period. Simple pain medication and anti-inflammatories, taken as your GP advises, can settle the ache enough for you to do your exercises. We do not promise any particular result from medication; it is there to make physiotherapy and daily life more comfortable while we work out what your hip needs next.

If these steps have not given you enough improvement, we talk through surgery. The main option for adults is an operation that cuts the bone of the socket and repositions it, so the cup wraps around the ball the way it should. This spreads your weight across a wider patch of cartilage and takes pressure off the rim. It aims to keep your own hip working for as long as possible and slow down wear-and-tear arthritis. Sometimes a keyhole look inside the joint is combined with it, to tidy up a torn labrum. If the joint is already badly worn, a total hip replacement may be the better choice instead. We will explain which option fits your hip, and you decide together with us what to do next.

What to expect¶

Hip dysplasia does not usually settle on its own. Because your socket covers less of the ball than it should, the same small patch of cartilage takes the strain every time you walk or stand. Over the years that patch wears down, and the ache you feel now tends to become more constant rather than come and go. Left alone, a shallow socket is a well-known cause of wear-and-tear arthritis arriving early in adult life.

How quickly that happens varies a lot from hip to hip. Some hips with mild changes stay serviceable for years, while others wear out sooner. If early wear-and-tear changes have already appeared on your X-rays, roughly one in three people with your pattern of hip shape go on to need a total hip replacement within 10 years, and about two in three within 20 years. Those are averages, not a prediction for you, and the exact shape of your socket affects where you sit on that range.

With the right treatment, the outlook can be very different. The operation that repositions your socket aims to spread your weight across more cartilage and slow that wear down. In well-chosen patients it relieves pain and improves how the hip works. Most active people who have this surgery return to their previous activity levels or higher. Your own hip can keep working for a long time: about 86% of hips are still going without needing a replacement 10 years later, and about 60% at 20 years. By 30 years, about 29% of hips are still preserved, which is honest to say: many hips do eventually wear out and need a replacement later in life.

A few things work against a good result, and your surgeon will weigh these up with you. Older age at the time of surgery, arthritis that is already established before the operation, and a joint that does not fit together smoothly all make the outcome less reliable. If the hip is already badly worn, a total hip replacement is usually the more dependable choice, and people who have one for dysplasia can expect reduced pain and better function, with replacement rates similar to anyone else having the same operation.

When to see someone¶

See your GP if you have a deep ache in the front of your groin or on the outside of your hip that keeps coming back with activity, especially if it worsens through the day or with long walks and standing. Ask for a specialist review if the ache has not settled after a few months of changing your activity, or if you notice clicking or snapping deep in the groin, a limp or waddle, or you have started cutting back on what you do because of the hip. Tell your GP if a parent, brother or sister has had hip dysplasia or an early hip replacement, or if you had treatment for a dislocated hip as a child. These details help decide how quickly you should be seen.

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