Hip Dysplasia in Adults: DDH, Perthes, and the Path to Hip Replacement

Hip dysplasia and the related developmental conditions — DDH (developmental dysplasia of the hip) and Legg-Calvé-Perthes disease — are some of the most under-recognized causes of hip pain in adults. Patients with these anatomic predispositions often develop symptomatic hip arthritis in their 20s, 30s, or 40s rather than their 70s, having spent years being told they are simply “too young” for hip problems.

The unifying concept is straightforward: anatomy that loads the hip abnormally over decades — and the right treatment depends entirely on where you are on the continuum from healthy anatomy to advanced hip arthritis.

What hip dysplasia actually is

Hip dysplasia is an anatomic condition in which the ball and socket of the hip are not optimally shaped or positioned. The most common pattern in adults is acetabular dysplasia — a shallow or undercovered socket — which leaves the femoral head less contained and less stable in the joint. The result is abnormal load distribution across the joint surfaces, which accelerates the wear-and-tear process that leads to arthritis.

Dysplasia can be present from birth (DDH), can result from childhood conditions like Perthes that alter the shape of the femoral head, or can be a milder undercoverage that was never diagnosed in childhood and only becomes apparent in adulthood when hip pain begins.

DDH — developmental dysplasia of the hip

DDH refers to a spectrum that ranges from a shallow but well-located hip socket all the way to a hip that is dislocated at birth. It is the most common form of hip dysplasia and is more common in females, first-born children, breech presentations, and those with a family history.

Two common adult-presentation patterns:

• Diagnosed and treated in infancy. Most modern newborn screening catches DDH early, and bracing or surgery in infancy gives the joint the best chance of developing well. These patients do better long-term than those untreated, but still carry a higher-than-average risk of hip pain and arthritis as adults.
• Mild dysplasia missed in childhood. Many adults presenting with hip pain in their 20s–40s have mild acetabular dysplasia that was never picked up. The pain is often the first sign — sometimes after pregnancy, weight gain, or a period of increased activity exposes the underlying loading problem.

Legg-Calvé-Perthes disease in adulthood

Legg-Calvé-Perthes (often shortened to “Perthes”) is a childhood condition in which the blood supply to the femoral head is temporarily disrupted, causing part of the ball of the hip to lose its blood supply and collapse. The body eventually restores blood flow and the bone remodels — but the femoral head is often left misshapen, flattened, or enlarged compared with a normal hip.

That altered shape loads the joint abnormally for the rest of the patient's life. Adults with a Perthes history commonly present with hip pain in their 30s–50s, often with a clear history of childhood treatment, and weight-bearing X-rays that show the characteristic head shape plus accelerated arthritis.

How dysplasia fits the anatomic-cause spectrum

Hip dysplasia, DDH, Perthes, and femoroacetabular impingement (FAI) are often discussed as separate diagnoses, but they sit on the same broader spectrum: anatomic variations of the hip that abnormally load the joint over decades and predispose to early arthritis.

In textbook terms, dysplasia and FAI are opposites — too little coverage versus too much contact — but many adults have features of both. Many adults presenting with what looks like a labral tear actually have an underlying anatomic cause, and treating the labrum without recognizing the dysplasia or FAI underneath often disappoints. Understanding these conditions together is the clarifying frame.

How dysplasia causes hip damage over time

The damage pattern from dysplasia follows a familiar progression:

1. Abnormal load distribution. The undercovered or misshapen joint surface concentrates pressure on a smaller area than a normal hip, accelerating cartilage wear at the point of greatest contact.
2. Labral irritation and tear. The labrum often fails under the abnormal loading. This is why a high percentage of young adults with labral tears are found to have underlying dysplasia or FAI.
3. Articular cartilage damage. With continued abnormal loading, the joint cartilage at the over-loaded zone begins to thin and wear. This is the start of arthritis.
4. Progressive arthritis. The joint enters the same wear process as any arthritic hip, but typically years or decades earlier than a normally shaped hip would.
5. Symptomatic arthritis and replacement consideration. When arthritis becomes limiting despite nonsurgical care, hip replacement becomes the right conversation.

What it feels like in adulthood

Adults with hip dysplasia or post-Perthes anatomy commonly describe:

Where am I on the continuum?

As with FAI, the most important question once dysplasia is identified is where you are on the dysplasia-to-arthritis continuum. The answer comes from your symptoms, an exam, and weight-bearing X-rays of the hip.

• Stage 1 — Dysplasia without arthritis. Symptoms but a well-preserved joint on imaging. Hip-preservation surgery (typically PAO for DDH) can address the underlying anatomy and may delay or prevent the development of arthritis.
• Stage 2 — Dysplasia with early arthritis. Some cartilage loss or early arthritic changes. Preservation surgery here has less reliable results; nonsurgical management is usually the right starting point.
• Stage 3 — Dysplasia with advanced arthritis. The arthritis is now the dominant problem. Hip replacement becomes the conversation when symptoms become limiting.

Treatment at each stage

Stage 1 — Symptomatic dysplasia, no arthritis

For younger adults with symptomatic acetabular dysplasia and a healthy joint, the standard hip-preservation operation is a periacetabular osteotomy (PAO) — a procedure that reshapes the bone around the socket to provide better coverage of the femoral head. Performed in well-selected patients with no arthritis, PAO has good long-term outcomes and can meaningfully delay the development of arthritis.

Stage 2 — Dysplasia with early arthritis

This is the most nuanced group. Preservation surgery in a dysplastic hip that has already developed arthritis tends to disappoint — the underlying joint surface is the actual driver, and addressing only the bony anatomy may not change it. The right pathway is usually nonsurgical:

• Activity modification to reduce the loading patterns that flare the joint
• Physical therapy focused on hip stability and balanced mobility
• Weight management, where it applies
• Ultrasound-guided injections. The hip joint is deep, so accurate placement matters — ultrasound-guided cortisone or PRP injections can provide meaningful relief and help confirm that the joint itself is the source of pain.

Stage 3 — Dysplasia with advanced arthritis

When the arthritis becomes the dominant problem and is meaningfully affecting your life despite nonsurgical care, hip replacement becomes a reasonable conversation. Modern hip replacement — particularly through the direct anterior approach — is highly durable (more than 90% remain intact at 30 years) and dramatically improves quality of life. See signs you may need a hip replacement for what that conversation usually looks like.

Replacing a dysplastic hip

Hip replacement in a dysplastic hip is technically more demanding than a standard primary replacement. The differences worth understanding:

• Smaller, less well-formed socket. Acetabular components often need to be smaller and positioned carefully to achieve adequate bone coverage. In severe dysplasia, the socket may need to be reconstructed.
• Leg-length differences. Dysplastic hips frequently have anatomic leg-length differences that need to be planned for during surgery.
• Femoral anatomy. The shape of the femur can be abnormal, particularly after Perthes or prior childhood surgery, which affects implant selection.
• Prior hardware. Patients who had previous preservation surgery (PAO, bracing-related hardware) may have retained metal that needs to be addressed.

What patients tell me

Adults with dysplasia tend to share a few familiar themes:

The age at presentation varies, but the underlying story is the same: anatomy that has been loading the hip abnormally for decades has finally produced symptoms that need treatment.

Next step

If you have a childhood history of DDH or Perthes — or if you have been told as an adult that you have hip dysplasia — the most useful thing you can do is get an honest assessment of where you are on the continuum. Weight-bearing X-rays, a clinical exam, and a clear conversation about your symptoms will determine the right next step. For some patients, that means nonsurgical care for years. For others, it means a well-timed and carefully planned hip replacement that can give them their life back.