Perthes disease (also called Legg-Calvé-Perthes disease) is a childhood hip condition where the blood supply to the “ball” of the hip joint (the femoral head) is temporarily disrupted. Without normal blood flow, part of the bone becomes weak and can change shape. Over time, the body replaces the damaged bone with new bone, but during this healing window the hip is vulnerable to flattening and stiffness.
Most children with Perthes disease first show symptoms between about 4 and 10 years of age. It often starts subtly, with a limp that comes and goes. Some children feel pain in the hip, groin, thigh, or even the knee.
Physiotherapy for Perthes disease focuses on protecting the hip while it heals, maintaining hip range of motion, supporting walking and running mechanics, and guiding a safe return to activity. A physiotherapist also helps families make practical decisions: which activities are safest right now, how to manage school sport, and when crutches might reduce flare-ups.
Key Facts
Risk Factors
- Age between 4 and 10
- Male sex
- Family history
- Reduced growth or being smaller for their age
Symptoms
- Limping, especially after activity or at the end of the day.
- Hip, groin, or knee pain.
- Reduced hip movement, commonly into abduction and internal rotation.
- Decreased running speed, skipping, or jumping compared with peers.
- Fatigue with walking long distances.
Aggravating Factors
- Running, jumping, and impact sports (football, basketball, netball).
- Prolonged walking, especially on hard surfaces.
- Deep squatting or sitting cross-legged for long periods.
- Rapid growth phases where tightness and coordination changes can increase hip stress.
Causes
Perthes disease is considered “idiopathic”, meaning the exact cause is not fully understood. The core problem is a temporary reduction in blood supply to the femoral head. When this happens, the bone becomes softer and more vulnerable to flattening under load.
Most children with Perthes disease have no single clear trigger. Research suggests it is likely that several influences may combine, such as growth patterns, circulation factors, and mechanical loading.
How Is It Diagnosed?
Diagnosis usually starts with a clinical assessment and is confirmed with imaging.
A physiotherapist will assess:
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Hip range of motion (particularly abduction and internal rotation)
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Gait (walking and running pattern) and compensations
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Strength and control of the hip and trunk
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Functional tolerance (how far they can walk before symptoms change)
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Activity history, including any recent spikes in sport or growth changes
Early Perthes can be subtle on initial X-rays, so follow-up and sometimes magnetic resonance imaging is used when symptoms persist but X-ray findings are unclear.
Investigations & Imaging
- X-ray (pelvis and frog-leg lateral views)
- Shows changes in the femoral head shape and density over time, helps stage the condition and monitor healing.
- Magnetic resonance imaging
- Can detect early changes before X-ray is clearly abnormal and gives detail on bone and cartilage involvement.
Grading / Classification
- Waldenström stages
- Describes radiographic stages over time: initial, fragmentation, reossification, and healed stage. Often used to understand where the child is in the disease process.
- Herring (lateral pillar) classification
- Used during fragmentation to estimate severity based on how much of the lateral “pillar” of the femoral head has collapsed. Commonly used to help guide treatment decisions and prognosis.
- Stulberg classification (outcome classification)
- Used at or near skeletal maturity to describe the final shape of the femoral head and how well it matches the socket, which relates to long-term joint health risk.
Physiotherapy Management
Exercise
Perthes disease physiotherapy exercises are designed around two priorities: keep the hip moving (so it does not stiffen into harmful positions) and strengthen muscles that protect the joint without overloading the healing bone. Early on, your physiotherapist often emphasises gentle hip abduction and rotation mobility (within comfort), plus controlled strengthening for the gluteal muscles (buttock), deep hip stabilisers, and trunk. As symptoms settle and imaging shows progression into safer healing phases, exercises progress toward functional strength: step control, single-leg balance, light hopping preparation, and gradual return-to-running drills. Exercise choices and intensity are staged carefully because “too much too soon” can flare pain and guarding, which then reduces hip motion and can increase joint compression during walking.
Activity Modification
Activity modification is a big part of physiotherapy for Perthes disease and often makes the biggest difference to day-to-day symptoms. This usually means temporarily reducing high-impact and contact activities, limiting long runs, and swapping to lower-impact options (for example, swimming or cycling) depending on the child’s symptoms and medical guidance. A physiotherapist helps families find a plan that is realistic: managing school sport expectations, setting “green light/amber light/red light” rules for pain and limping, and building an alternative fitness routine so a child still feels active and included.
Manual Therapy
Manual therapy is not about forcing the hip. In Perthes disease rehab, gentle hands-on techniques can help reduce protective muscle tightness around the hip and maintain comfort so the child can keep moving normally. A physiotherapist may use soft tissue techniques to address tight hip flexors, adductors, and gluteal muscles, and gentle joint techniques when appropriate. The goal is improved hip motion and gait quality, not aggressive stretching.
Postural Retraining
Children with Perthes disease commonly adopt compensations like trunk leaning, turning the foot out, or avoiding hip extension. Postural retraining in this context is really movement retraining: helping the child walk with less limp, improving pelvic control, and reducing “hip hitching” strategies that can increase joint irritation. Physiotherapists often use simple cues, mirrors, games, and short practice bouts to improve movement patterns without making therapy feel medical or intimidating.
Education
Education is essential in physiotherapy for Perthes disease because the condition lasts a long time and symptoms can fluctuate. A physiotherapist will help you understand: why limping matters (it changes load through the hip), why hip stiffness can worsen symptoms, what pain levels are acceptable, and how to track progress over weeks rather than day-to-day. Education also includes school and sport communication tips, and strategies to keep a child engaged and confident while activity is limited.
Other
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Gait aids: A physiotherapist may recommend crutches during painful phases or when limping becomes persistent, to reduce hip load and settle symptoms.
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Cross-training plan: Building aerobic fitness through low-impact options, plus strength and coordination work, can make return to sport smoother later.
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Return-to-sport planning: Perthes disease rehab often needs a staged plan with checkpoints (symptoms, function, sometimes imaging guidance) rather than a fixed date.
Other Treatments
Other treatments may be used alongside physiotherapy depending on symptom severity and specialist recommendations:
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Pain relief medicines (as advised by a doctor) to help a child stay comfortable enough to move normally and participate in Perthes rehab exercises.
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Temporary reduced weight bearing, including crutches, to manage painful flare-ups and reduce limping.
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Planned rest periods from impact sport during active phases of the disease.
In general, the most helpful combination is consistent follow-up with a paediatric orthopaedic team plus physiotherapy for Perthes disease that is adjusted to the child’s stage, symptoms, and function.
Surgery
Surgery is not required for every child with Perthes disease. When it is considered, the usual goal is “containment”, meaning keeping the femoral head sitting well inside the hip socket so it can heal in the roundest shape possible. Surgical options may include femoral osteotomy (changing the angle of the femur) and/or pelvic osteotomy (changing the socket orientation). Surgical decisions are typically influenced by the child’s age, hip stiffness, and severity classifications on imaging.
Physiotherapy is important both before and after surgery. Pre-operative physiotherapy focuses on maintaining hip motion and strength so recovery is smoother. Post-operative physiotherapy guides protected weight bearing as directed by the surgeon, restores hip range of motion safely, rebuilds strength and walking quality, and gradually reintroduces running and sport-specific skills when cleared. Perthes disease physiotherapy exercises after surgery are progressed carefully to avoid overload while still preventing stiffness.
Prognosis & Return to Activity
Perthes disease is usually a long-term process with ups and downs. Many children do well, especially when they maintain hip motion and avoid repeated high-impact flare-ups during vulnerable phases. Prognosis is influenced by age at onset (younger children often have more remodelling potential), hip stiffness, and how much of the femoral head is involved.
Return to activity is usually staged rather than date-based. In Perthes disease rehab, a physiotherapist typically looks for: minimal or no limp, good hip range of motion (especially rotation and abduction), good hip and trunk strength, and the ability to tolerate walking and low-impact activity without next-day flare-ups. Higher-impact activities are reintroduced gradually, often starting with short run-walk intervals, then change-of-direction drills, then jumping and sport-specific training. Some children will need longer periods away from contact or high-impact sport to protect the healing hip.
Complications
- Persistent hip stiffness, particularly loss of hip rotation and abduction.
- Ongoing limp and compensatory movement patterns that can irritate the back, knee, or other hip.
- Leg length difference due to changes in femoral head and growth patterns.
- Femoral head deformity (flattening) which can increase the chance of hip impingement symptoms later.
- Higher risk of hip osteoarthritis in adulthood, especially with poorer final femoral head shape.
When to See a Physio
- Your child has a limp lasting more than a few days, even if pain is mild.
- Hip, groin, thigh, or unexplained knee pain that keeps returning.
- Your child is losing hip movement, struggling with stairs, or avoiding sport.
- You have a Perthes diagnosis and want a clear Perthes disease rehab and activity plan.
- You need guidance on crutches, school sport modifications, or a graded return to running program.