Periacetabular Osteotomy (PAO): The Hip Dysplasia Surgery Explained

Key Takeaways

• Periacetabular osteotomy reshapes and repositions the hip socket so it covers the ball of the joint more fully, which may ease pain and slow the wear that can lead to early arthritis.
• The surgery usually suits younger, skeletally mature people with hip dysplasia whose joint cartilage is still in reasonable condition, rather than those with advanced arthritis.
• Recovery is gradual and typically involves crutches for several weeks, with most activities returning over roughly six to 12 months.
• Non-surgical care such as physiotherapy is often explored first, and the choice to operate depends on your symptoms, imaging and personal goals.

Hip pain that settles into the groin during a run, a deep squat or a long day on your feet can have many causes. For some younger adults, the reason lies in the shape of the hip socket itself. A periacetabular osteotomy is one of the operations used to correct that shape when hip dysplasia is the cause. When the socket is too shallow to cover the ball of the joint, the hip loads a smaller area than it should, which can bring pain, instability and, over time, wear that may lead to arthritis.

The decision to operate is rarely simple, and it depends on your symptoms, imaging and what you want from your hip. Understanding the surgical options and discussing them with a hip dysplasia surgeon can help, alongside non-operative care.

What Is Periacetabular Osteotomy?

Periacetabular means around the acetabulum, the cup-shaped socket of the hip, and osteotomy means a controlled cut to bone. The procedure cuts the bone around the socket, frees it from the pelvis and rotates it to cover the ball of the joint more completely. Its value comes down to how this changes the mechanics of the hip:

The Shallow Socket Problem

In a healthy hip, the ball at the top of the thigh bone sits snugly inside a deep, well-shaped socket. With hip dysplasia, also called developmental dysplasia of the hip, the socket is shallow or tilted, so it does not cover the ball as it should. Body weight then presses through a smaller contact area, concentrating stress on the rim of the socket and the ring of cartilage, known as the labrum, that lines it. This is the mechanical problem the surgery aims to correct.

The Purpose of the Osteotomy

The aim is not to replace the joint but to preserve it. Reorienting the socket increases the area of contact between the ball and socket, improves stability and spreads load more evenly across the cartilage. This may reduce pain, improve how the hip functions and slow the joint wear that can progress towards arthritis at a young age.

The Contrast With Hip Replacement

Unlike a total hip replacement, which removes the damaged joint surfaces and fits artificial components, a periacetabular osteotomy keeps your own hip and changes only the position of the socket. This is why it is often called a hip preservation procedure and is generally offered before significant arthritis sets in. For younger, active people, preserving the joint may delay, or sometimes reduce, the likelihood of needing a replacement later, though this varies from person to person.

Exploring Non-Surgical Care First

Surgery is rarely the first step. For milder dysplasia, or when symptoms are manageable, a period of non-operative care is often trialled to settle pain and build strength around the joint. It may not change the shape of the socket, but it can improve comfort and function and clarify how much the dysplasia is contributing to your symptoms. It usually draws on a few approaches:

Physiotherapy and Strengthening Work

Targeted physiotherapy focuses on the muscles that support and control the hip, including the glutes, deep core and muscles around the pelvis. Stronger, better-coordinated muscles can take some load off the joint and improve stability, which may ease day-to-day pain. A tailored program, adjusted as you progress, tends to help more than generic exercises, since everyone’s hip, goals and starting point differ. It can help to weigh up physiotherapy or surgery before committing to a procedure.

Activity and Load Adjustments

Changing how you load the hip can also help. This might mean easing off deep squatting, prolonged running or positions that combine bending and rotation, while keeping up low-impact movement such as swimming or cycling. The goal is not to stop moving, but to move in ways that irritate the joint less.

Shared Decisions About Surgery

When pain persists despite consistent non-operative care, or imaging shows the socket is too shallow to protect the joint over time, surgery may become an option. This is usually a shared decision that weighs your symptoms, imaging, age and goals. Seeking a second opinion is reasonable for an operation of this size and can help you feel confident in your decision.

Who Might Be a Candidate for PAO?

Suitability is decided case by case after an assessment that usually includes a physical examination and imaging such as X-rays, and sometimes magnetic resonance imaging (MRI) or computed tomography (CT) scans. A few factors tend to guide the discussion:

Age and Skeletal Maturity

The surgery is generally offered to skeletally mature adolescents and adults, most often between the late teens and around 40 years of age. Age was once seen as a firm cut-off, but current thinking places more weight on the health of the joint than on age alone. Younger, active people who want to stay mobile are common candidates.

Cartilage and Joint Health

Because the operation preserves the natural joint, it tends to suit hips where the cartilage is still in reasonable condition. When arthritis is advanced and the cartilage is significantly worn, reorienting the socket is less likely to help, and a different approach may be more appropriate.

Symptoms and Warning Signs

Common symptoms that lead to an assessment include:

• Groin or hip pain that worsens with activity
• Clicking, catching or locking in the hip
• Instability, or a feeling the hip may give way
• Pain after prolonged sitting, walking or running
• Aching that lingers after sport or exercise
• Limping that comes and goes

These symptoms overlap with other hip conditions, so they warrant an assessment rather than pointing to a diagnosis on their own.

Suitability and Risk Factors

Beyond age and cartilage, factors such as higher body weight, smoking and the degree of existing joint wear have been linked with a greater chance of complications in some studies, so a surgeon may raise these beforehand. Working on what you can change, like fitness and smoking, may support recovery. These factors are weighed together, and none automatically rules a person in or out.

How the PAO Procedure Works

A periacetabular osteotomy is carried out in hospital under a general anaesthetic and usually takes around two to three hours. Live X-ray guidance, called fluoroscopy, is used throughout to protect the surrounding nerves and muscles and to check the position of the bone. Preparation and the operation move through a few stages:

Preparing for the Operation

Preparation begins before the day of surgery. Your team will review your imaging, general health and medications. Building strength and fitness beforehand, an approach called prehab before surgery, can make the early weeks after the operation feel more manageable.

Repositioning the Acetabulum

The surgeon makes a series of precise cuts through the pelvic bone around the socket, freeing the acetabulum without disturbing the ring of the pelvis. The freed section is then rotated into a position that covers the ball of the joint more fully and shares load more evenly.

Securing the Bone With Screws

Once the socket sits in its corrected position, the surgeon fixes it with several screws, commonly around three, which hold the bone steady while it heals. Over the following weeks, new bone forms across the cuts and locks the socket into its new alignment. The screws are sometimes removed later in a small day procedure if they cause irritation, though many people keep them without trouble.

Confirming Alignment With Imaging

Before the operation finishes, X-ray images confirm that the socket and screws sit correctly. In selected cases, the surgeon may also address other issues at the same time, such as repairing a torn labrum with a hip arthroscopy or, less commonly, adjusting the upper thigh bone. Whether these steps are needed depends on your anatomy and is often confirmed during surgery.

What Recovery After PAO Looks Like

Recovery from a periacetabular osteotomy is gradual and measured in months rather than weeks. The timeline is fairly predictable, so knowing what to expect helps you plan support at home, time off work and the return to the activities you enjoy. Recovery tends to unfold across a few stages:

The Hospital Stay

Most people stay in hospital for two to four days. Physiotherapy usually starts the day after surgery, with simple movements and learning to walk safely with crutches. Pain and some numbness around the wound are common at first and can be managed with medication and support from your care team.

The Early Weeks on Crutches

For roughly the first six weeks, crutches keep weight off the operated hip while the bone heals, often with only light, partial weight through the leg as directed. Arranging help at home for the first week or two helps, since everyday tasks take more effort. Keeping the wound clean and following your team’s instructions supports healing.

The Return to Full Weight Bearing

Weight through the leg is usually increased from around the six to eight week mark, once healing is progressing well, moving from two crutches to one and then to walking unaided. Strengthening exercises and low-impact activities such as cycling or swimming are typically reintroduced around this time. Many people walk without support by about three months, though this varies.

The Path Back to Sport

Higher-impact activities and sport are reintroduced later, often between six and 12 months after surgery, depending on how the hip responds and the demands of the activity. A structured program guided by your clinician helps you rebuild strength and confidence safely. Feeling fully recovered can take up to a year, and rushing may raise the risk of setbacks.

These timeframes are a general guide only. Your recovery may be faster or slower depending on your circumstances and your surgeon’s advice.

Benefits and Risks to Weigh Up

Like any major surgery, a periacetabular osteotomy carries both benefits and risks. The balance differs for everyone, so it is worth weighing each side with your specialist:

Pain Relief and Joint Preservation

The benefits centre on keeping your own hip. Reported advantages include:

• Reduced hip and groin pain for many people
• Improved stability and hip function
• More even load across the joint cartilage
• Possible delay in, or reduced need for, hip replacement
• Greater ability to stay active and return to valued activities

Studies generally report meaningful improvements in pain and function, though results differ between individuals and cannot be promised.

Risks and Possible Complications

No operation is without risk. Possible complications include infection, blood clots, bleeding, nerve irritation or numbness around the incision, and delayed or incomplete bone healing. In some cases further surgery is needed, and a small number of people still progress to a hip replacement over time. Reported complication rates vary between studies and surgeons and are influenced by factors such as age, body weight and smoking. Your care team takes steps to lower these risks, such as measures to prevent blood clots and close monitoring during your recovery. Your surgeon can talk through the risks most relevant to you.

Durability and Long-Term Outcomes

Longer-term results are encouraging for well-selected patients, with many keeping their own hip for years or even decades. Some studies report that most hips are preserved well beyond a decade, particularly when there was little arthritis at the outset. Even so, a periacetabular osteotomy is not a permanent fix for every hip, and some people need further treatment later.

Getting the Right Support for Your Hip

Hip dysplasia tends to respond better when it is understood early and managed with a plan built around your goals. Whether that means movement-based care, a clear diagnosis or a conversation about surgery, the useful first step is a proper assessment of what is driving your symptoms and what your options are.

When hip pain is holding you back from the activities you love, consider booking an appointment with the team at MTP Health, or speak with your general practitioner (GP) for a referral to a specialist who can assess your hip and discuss whether surgery or non-operative care suits you.

Frequently Asked Questions (FAQs)

1. How long does a periacetabular osteotomy take?

The operation usually takes around two to three hours, though the exact time depends on your anatomy and whether steps such as a labral repair are carried out at the same time. Expect to spend longer in theatre overall, once anaesthetic and preparation are included.

2. Is a PAO considered major surgery?

Yes. It involves controlled cuts to the pelvic bone and a period of protected weight bearing afterwards, so recovery is measured in months. Many people take time to feel confident before going ahead.

3. How painful is recovery after the operation?

Discomfort is expected in the early days and is usually managed with medication and guidance from your care team. Pain tends to ease over the first few weeks as healing progresses and you regain movement. Everyone experiences this differently, and your team can tailor pain relief and activity to your needs.

4. Will I still need a hip replacement one day?

Not necessarily. For many people, a periacetabular osteotomy preserves the natural hip for a long time and may delay or reduce the likelihood of a replacement. It cannot prevent this in every hip, though, and some people do have a hip replacement later, especially if arthritis was already present before surgery.

5. Can hip dysplasia be treated without surgery?

Milder cases can sometimes be managed with physiotherapy, strengthening and activity adjustments, which may ease symptoms even though they do not change the shape of the socket. Whether this is enough depends on the severity of the dysplasia and how the joint is coping. A tailored assessment with a physiotherapist or specialist can help you understand your options, and the team at MTP Health can guide you through movement-based care.

6. How soon can I return to work or driving?

This depends on your job, your recovery and your surgeon’s advice. Desk-based work may be possible within a few weeks, while physical roles often need longer. Driving usually resumes once you are off strong pain medication, can move the leg safely and are no longer relying on crutches, which your surgeon will confirm. Timelines vary from person to person.

This article is general information only and does not take into account your individual circumstances. It is not a substitute for personalised medical advice. For guidance about your own hip, please speak with a qualified health professional such as your GP, physiotherapist or orthopaedic specialist.