Legg Calve Perthes Disease

Overview

Legg-Calvé-Perthes disease (often just called Perthes disease) is a childhood hip problem. The hip joint is a ball-and-socket joint: the top of the thigh bone is shaped like a ball and it sits inside a socket in the pelvis. In Perthes disease, the blood supply to that ball (the femoral head) is interrupted for a while. Without enough blood, the bone softens and can crack or flatten. Later, the body grows new blood vessels into the area and the bone slowly heals and reshapes. The whole process usually takes months to a few years, and the aim of treatment is to keep the ball as round as possible while it heals.

It is uncommon rather than rare. It affects roughly 1 in 10,000 to 1 in 12,000 children, so most family doctors will see only a handful of cases in their career. Because it is uncommon, children with a limp are often checked for more common problems first.

It mostly affects young children, usually between 4 and 10 years of age, and it is about four to five times more common in boys than in girls. It happens in all ethnic groups and all parts of the world. Children who are small for their age or who have a late growth spurt seem slightly more likely to be affected. It is not caused by carrying heavy bags, sports, or a child's diet.

Symptoms

Common symptoms

• A limp, which may come on slowly and get worse over weeks
• Pain in the groin, hip, thigh or knee — knee pain is a common trick, because the hip and knee share the same nerve supply
• Stiffness, especially first thing in the morning or after sitting still
• Pain that gets worse with running, jumping or long walks and eases with rest
• Holding the leg slightly turned outward, or walking with the foot turned out
• Not wanting to take part in PE or play as much as usual
• Muscle wasting or a slightly thinner thigh on the affected side if the limp has been going on for a while

Symptoms in children

• Limping or walking on tiptoe
• Complaining of a 'bad knee' rather than a bad hip
• Being clingy, tired or grumpy after activity
• Reluctance to walk long distances or to keep up with friends
• Sometimes no pain at all — just an unexplained limp that does not go away

Symptoms in older adults

• This condition starts in childhood, so it is not a new illness in adults. Adults who had Perthes disease as children may notice hip stiffness, a shorter leg, or earlier-than-usual hip wear and tear (osteoarthritis) in middle age.
• Older adults with hip pain should be checked for the many other causes of hip pain, such as osteoarthritis.

Causes

Main causes

• The exact cause is not known. The key problem is a temporary loss of blood supply to the ball of the hip joint (the femoral head).
• Experts think several things may combine: slightly unusual blood vessel patterns around the hip, small blood clots, increased pressure inside the bone, or a period of rapid growth that outpaces the blood supply.
• It is not caused by injury, sport, poor diet, or by anything a parent did or did not do.

Risk factors

• Being a boy (about four to five times more common)
• Being between about 4 and 10 years old
• Being small for age or having delayed bone growth
• A family history of Perthes disease in a small number of cases
• Certain blood clotting tendencies (in a minority of children)
• Second-hand smoke exposure has been suggested as a possible contributing factor in some studies

When to see a doctor

See a doctor urgently if:

• A limp that lasts more than a few days or keeps coming back
• Hip, groin, thigh or knee pain that limits walking or play
• Fever with hip pain or refusal to put weight on the leg (seek same-day or emergency care)
• A child who stops walking or refuses to stand

Book a routine appointment if:

• A limp that has improved but is still there after a couple of weeks
• Stiffness in the hip in the morning
• A child who had Perthes disease before and now has new pain or stiffness
• Questions about sport, school PE or follow-up appointments

Diagnosis

A doctor will start by asking about the limp, the pain, how long it has been going on, and whether there have been any injuries or illnesses. They will watch your child walk and examine the hip, checking how far the leg can move in different directions. If Perthes disease is suspected, they will usually arrange an X-ray of the hip. Early on, X-rays can look normal, so if symptoms continue the doctor may repeat the X-ray or arrange an MRI scan.

Tests that may be done

• Physical examination — checking walking, hip movement and thigh muscle bulk
• Plain X-ray of the hips (front and frog-leg views)
• MRI scan, which can show the problem earlier than an X-ray
• Bone scan (used less often now)
• Blood tests to rule out infection or inflammation if there is fever or the child is unwell
• Repeat X-rays over months to see how the bone is healing and to plan treatment

What to expect at your appointment

You will usually be referred to a children's orthopaedic team (bone and joint specialists) if Perthes disease is confirmed or suspected. Expect regular check-ups, often every few months at first, with X-rays to track healing. Your child's doctor will talk with you about activity, school and sport, and about what stage of healing the hip is in. Ask as many questions as you like — it helps to write them down before appointments.

Treatment

The goal of treatment is to keep the hip comfortable and mobile and to help the ball of the hip joint heal as round as possible. Some children need very little treatment beyond rest from impact activities and regular check-ups. Others need more support, such as physiotherapy, crutches, a brace, or occasionally surgery. The right plan depends on the child's age, how much of the bone is affected, and how the hip looks on X-ray. Every child is different, and your specialist team will tailor the plan to your child.

Self-care at home

• Follow the advice from your child's specialist about which activities to avoid for now — often running, jumping and contact sports are paused while the hip is healing
• Keep swimming and gentle cycling if your doctor says it is fine; these keep the hip moving without hard impact
• Simple pain relief can be discussed with your pharmacist or doctor — always ask before giving any medicine to a child
• Keep up with school and normal routines where possible; most children can still attend school
• Encourage your child to keep the hip moving with gentle stretches taught by a physiotherapist
• Put a small cushion or folded towel under the hip at rest if it feels more comfortable
• Note down any changes in pain or walking so you can tell the doctor at the next visit

Medical treatments

Treatment is described in general terms, because the plan is personal to each child. Options include: watching and waiting with regular check-ups and X-rays; resting the hip from impact activities; physiotherapy to keep movement and strength; crutches to take weight off the hip; a period of traction (gentle pulling) in hospital in some cases; a brace or cast to hold the hip in a good position while it heals; and pain relief, which your doctor or pharmacist can advise on. Some children are also referred to a dietician or given vitamin D or calcium advice if their diet or growth needs support. Your child's specialist team will explain the pros and cons of each option for your child.

When is surgery considered?

Surgery is not needed for most children. It may be considered if the hip is badly flattened, if the hip keeps stiffening, or if the hip is not staying in a good position as the bone heals. Operations aim to improve the shape or position of the hip joint, sometimes by reshaping the bone of the pelvis or thigh so the ball sits better in the socket. Surgery may involve a short hospital stay and a period of limited activity afterwards. Your specialist team will discuss the risks and benefits with you in detail if they think surgery is the right choice.

Living with this condition

Life with Perthes disease usually means some changes to sport and play for a while, plus regular hospital visits. Many children cope well with a clear, simple explanation of why they need to take it easier for a time. Talk to the school so teachers and PE staff understand what your child can and cannot do. If your child needs crutches, a brace or a wheelchair for a while, ask the hospital team about support at school and about transport to appointments. Keep the focus on what your child can do, not only on what they cannot.

Lifestyle tips

• Keep gentle daily movement going — swimming, walking on flat ground and cycling if approved by your doctor
• Protect sleep: tiredness makes pain feel worse
• Keep a simple diary of pain and activity to spot patterns and share with the doctor
• Avoid smoking around your child — it is bad for blood vessels and general health
• Plan rest breaks on busy days such as school trips or family outings
• Encourage hobbies that do not depend on running or jumping — music, art, swimming, board games, cycling

Diet and exercise

There is no special diet for Perthes disease. A balanced, varied diet with enough calcium and vitamin D supports growing bones — dairy foods, leafy greens, beans and eggs are good sources, and some children may need a supplement, which your doctor or pharmacist can advise on. Exercise matters, but the type matters: gentle, non-impact movement keeps the hip flexible, while running, jumping and contact sports are usually paused while the hip is healing. A physiotherapist can give your child a safe set of exercises and stretches. Always check with your child's specialist before starting a new activity.

Mental health and emotional wellbeing

It is normal for children to feel frustrated, left out or worried when they cannot join in with friends, and for parents to feel anxious or guilty — even though nothing you did caused this. Children may worry about being different, about school, or about pain. Talk openly and simply, keep routines as normal as possible, and let your child's teachers know so they can help. Teenagers may feel more self-conscious about braces, crutches or scars. If your child seems persistently low, withdrawn, or very anxious, tell your doctor — support is available. If you or your child ever feel in crisis or have thoughts of harming yourself, contact your local emergency number or a crisis support service in your area straight away.

Prevention

There is no known way to prevent Legg-Calvé-Perthes disease, because the cause is not fully understood. What you can do is notice a limp early and get it checked, so the hip can be monitored and supported as soon as possible. Keeping children away from second-hand smoke and supporting a healthy, balanced diet is good for general bone and blood vessel health. Nothing you did caused this condition.

Screening programmes

There is no routine screening programme for Perthes disease. Children are usually checked when a parent or teacher notices a limp or when a child complains of hip, thigh or knee pain. Children who have had Perthes disease need long-term follow-up with X-rays until they finish growing, and sometimes into adulthood, to check the shape of the hip.

Complications

If left untreated

• The ball of the hip joint can become flattened or enlarged, changing the shape of the joint
• Stiffness or a shortened leg
• Earlier-than-usual wear and tear of the hip (osteoarthritis), sometimes needing hip replacement in later adult life
• Long-term pain or a limp, especially with heavy activity
• Difficulty with some sports or physically demanding jobs

Long-term outlook

The outlook is generally encouraging. The hip bone heals by itself over months to a few years, and with good monitoring and support many children end up with a well-shaped hip and no lasting problems. Younger children, especially those under about 6 to 8 years old, tend to do best because they have more growth and healing ahead of them. Some children — particularly those diagnosed later or with more severe changes — are left with stiffness or a higher chance of hip wear in adulthood, which is why long-term follow-up matters. There is a lot that can be done to support your child's hip, and most families find a workable routine while the bone heals.

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