Bilateral Perthes disease: Definition, Uses, and Clinical Overview

Posted on February 27, 2026 | by drhip

Bilateral Perthes disease Introduction (What it is)

Bilateral Perthes disease is a form of Legg–Calvé–Perthes disease that affects both hips.
It involves temporary loss of blood supply to the femoral head (the “ball” of the hip joint) in childhood.
Over time, the bone can soften, change shape, and then heal with remodeling.
The term is commonly used in pediatric orthopedics, radiology reports, and physical therapy planning.

Why Bilateral Perthes disease used (Purpose / benefits)

Bilateral Perthes disease is not a treatment or device; it is a diagnosis that helps clinicians describe a specific pattern of childhood hip disease affecting both sides. Using this diagnosis has practical benefits in care planning and communication:

Clarifies the cause of hip symptoms in children. Perthes disease can present with hip pain, groin pain, thigh pain, knee pain, a limp, or reduced hip motion. Naming the condition helps focus evaluation on the hip joint and its blood supply–related bone changes.
Guides imaging choices and monitoring. The diagnosis frames why serial X-rays and sometimes MRI may be used to track bone collapse, healing, and reshaping over time.
Supports staging and prognosis discussions. Clinicians often describe “stage” and “severity” based on imaging patterns, which can influence expectations about hip shape after healing and potential future arthritis risk.
Helps select a management approach. Treatment planning (often called “management” in this context) may range from observation and activity modification to bracing, physical therapy, or surgery, depending on age and hip shape. What is chosen varies by clinician and case.
Promotes whole-patient planning when both hips are involved. Bilateral involvement can affect gait, endurance, and rehabilitation planning more than one-sided disease, and it may influence how weight-bearing and strengthening are progressed.

Indications (When orthopedic clinicians use it)

Orthopedic clinicians use the diagnosis and workup of Bilateral Perthes disease in situations such as:

A child with a persistent limp and reduced hip abduction (difficulty moving the thigh outward)
Hip or groin pain that may be intermittent and worsens with activity
Referred pain to the thigh or knee with a relatively normal knee exam
Limited internal rotation of the hip on physical exam
X-ray findings suggesting Perthes changes in both femoral heads
MRI findings of reduced perfusion (blood flow) or early bone changes when X-rays are not yet diagnostic
Follow-up visits to stage disease activity (collapse/fragmentation/healing) and monitor hip shape over time

Contraindications / when it’s NOT ideal

Because Bilateral Perthes disease is a diagnosis rather than a procedure, it does not have “contraindications” in the usual sense. The closer practical issue is when the label does not fit well or when a different diagnostic pathway may be more appropriate.

Situations where clinicians may consider alternative explanations or different approaches include:

Not typical age or presentation. Perthes is classically a childhood condition; very atypical age ranges can prompt a broader differential diagnosis. Varies by clinician and case.
Signs pointing to infection or inflammatory disease. Fever, significant systemic symptoms, markedly elevated inflammatory markers, or severe acute pain may suggest a different condition requiring urgent evaluation.
History suggesting other causes of avascular necrosis. Some children have Perthes-like femoral head avascular necrosis associated with other medical conditions or treatments; the underlying cause may affect evaluation and planning.
Hip pain after significant trauma. Acute injury patterns may need fracture/dislocation assessment rather than a Perthes-centered approach.
Imaging patterns inconsistent with Perthes. Hip dysplasia, slipped capital femoral epiphysis (SCFE), tumors, or other disorders can mimic aspects of presentation and require different management.

How it works (Mechanism / physiology)

Bilateral Perthes disease reflects a process affecting the femoral head in both hip joints. The core mechanism involves temporary disruption of blood supply to the growing femoral head (avascular necrosis), followed by bone weakening and later healing.

High-level mechanism

Ischemia (reduced blood flow) leads to death of bone cells in the femoral head.
The weakened bone can lose structural strength, and the spherical “ball” may flatten or deform under everyday joint forces.
The body gradually removes damaged bone and replaces it with new bone through resorption and re-ossification (a healing and rebuilding cycle).
As healing continues, the femoral head can remodel toward a rounder shape, especially in younger children, but the final shape varies by case.

Relevant hip anatomy (plain-language explanation)

Femoral head: the “ball” at the top of the thigh bone.
Acetabulum: the “socket” in the pelvis.
Articular cartilage: smooth lining covering the bone ends; it can remain present while the underlying bone changes, which is one reason early disease may be subtle on X-ray.
Growth plate (physis): the developing region near the femoral head/neck in children; growth and remodeling potential relate to age and skeletal maturity.
Hip capsule and surrounding muscles: influence hip motion; muscle tightness and guarding can reduce range of motion and affect walking mechanics.

Onset, duration, and reversibility

Bilateral Perthes disease generally evolves over months to years, moving through phases of active disease and healing. It is often described as “self-limited” in the sense that revascularization and healing can occur, but the degree of reversibility of shape change is variable. Final hip shape and long-term symptoms depend on factors such as age at onset, extent of femoral head involvement, and how well the hip remains contained within the socket during healing. Varies by clinician and case.

Bilateral Perthes disease Procedure overview (How it’s applied)

Bilateral Perthes disease is not a single procedure. The “application” is the clinical workflow used to diagnose it, classify severity, and plan monitoring and supportive care. A typical high-level pathway looks like this:

Evaluation / exam – History of limp, activity-related pain, stiffness, or decreased motion – Physical exam focusing on hip range of motion (especially abduction and internal rotation), gait, and leg length differences
Preparation – Clinicians often rule out urgent causes of hip pain (infection, fracture, SCFE) based on history, exam, and targeted testing – Discussion with caregivers about likely diagnostic steps and the need for follow-up imaging over time
Intervention / testing – X-rays of the pelvis and hips to look for characteristic femoral head changes – MRI when early disease is suspected or to better define the extent of involvement; use varies by clinician and case – In some settings, additional tests may be used to evaluate for other diagnoses when presentation is atypical
Immediate checks – Review imaging for bilateral involvement, severity patterns, and any alternative diagnosis – Baseline documentation of hip motion and functional limitations
Follow-up – Repeat visits to monitor symptoms, hip motion, gait, and imaging changes over time – Adjustments in supportive measures (for example, physical therapy focus, mobility aids, or surgical referral considerations) based on progression and hip shape; varies by clinician and case

Types / variations

Bilateral Perthes disease can be described in several clinically meaningful ways. These “types” are not separate diseases, but they affect communication and planning.

Simultaneous (synchronous) vs sequential (metachronous) involvement
Both hips may be active at the same time, or one hip may be affected first with the second hip involved later.
Severity variation between hips
One hip may be more affected than the other, which can complicate gait patterns and rehab planning.
Stage of disease (time-phase descriptions)
Clinicians often describe stages such as early ischemic changes, fragmentation/collapse, and healing/remodeling stages. Terminology varies by clinician and case.
Classification systems for extent and prognosis
Several radiographic classification approaches are used in practice (for example, systems that describe the extent of femoral head involvement or “pillar” preservation). These are tools for communication and prognosis discussion rather than definitive predictors.
Perthes vs Perthes-like femoral head osteonecrosis
Some children have femoral head osteonecrosis associated with other conditions or treatments; clinicians may distinguish idiopathic Perthes disease from secondary causes because it can affect evaluation and management emphasis.

Pros and cons

Pros:

Provides a clear diagnostic framework for childhood hip pain and limp affecting both sides
Encourages timely hip-focused imaging and follow-up rather than attributing symptoms only to the knee or muscles
Helps clinicians communicate stage/severity and coordinate multidisciplinary care (orthopedics, physical therapy, radiology)
Highlights the need to assess gait and function globally when both hips are involved
Supports planning for school, sports participation, and activity expectations in a structured way (informational planning, not guarantees)

Cons:

Can be difficult to diagnose early, especially if initial X-rays appear normal
Disease activity changes over time, so repeated visits and imaging may be needed
Bilateral involvement can increase functional limitations and rehabilitation complexity
Final outcomes are variable; predicting long-term hip shape and symptoms is not exact
The term can be confused with other pediatric hip disorders without careful clinical correlation
Management options may involve prolonged monitoring, which some families find burdensome

Aftercare & longevity

Because Bilateral Perthes disease unfolds over time, “aftercare” generally means long-term follow-up and functional support rather than a short recovery window. Outcomes and longevity of hip function are influenced by multiple factors:

Age at onset and growth remaining. Younger children often have greater remodeling potential, but this is not a rule and varies by case.
Extent of femoral head involvement and hip shape during healing. How round the femoral head remains (or becomes) can influence later motion, impingement risk, and wear patterns.
Hip containment and range of motion. Maintaining usable motion (especially abduction and internal rotation) is often a monitoring focus because stiffness can affect gait mechanics.
Adherence to follow-up. Regular re-evaluation helps clinicians recognize progression, healing, and complications at appropriate times.
Rehabilitation approach and daily activity demands. Physical therapy goals commonly emphasize motion, strength, and gait efficiency, but specifics vary by clinician and case.
Bilateral functional load. When both hips are affected, fatigue, endurance limits, and compensatory movement patterns may be more prominent.
Comorbidities and overall health. Other medical conditions, neuromuscular factors, or differences in anatomy can influence function and long-term joint mechanics.

Long-term, some individuals do well with minimal limitations, while others may develop residual deformity that contributes to hip impingement or earlier degenerative changes. The range of outcomes is broad and depends on individual hip shape after healing and lifetime loading patterns.

Alternatives / comparisons

Bilateral Perthes disease is a specific diagnosis, so “alternatives” usually refer to either alternative diagnoses that can mimic it, or alternative management strategies used depending on severity and timing.

Compared with observation/monitoring

Observation and scheduled monitoring is commonly used when symptoms are mild, hip motion is acceptable, and imaging suggests a course likely to remodel adequately.
The tradeoff is that monitoring requires time and repeated reassessments, and decisions may shift as the disease evolves.

Compared with physical therapy-focused care

Physical therapy is often used to address motion limits, strength, and gait mechanics.
PT does not “reverse” avascular necrosis, but it may help maintain function and reduce secondary stiffness. Specific benefits vary by clinician and case.

Compared with bracing/casting and containment strategies

Some care plans focus on containment, meaning encouraging the femoral head to remain well-seated in the socket during healing to support a rounder remodeling environment.
The role and selection of bracing, casting, or surgical containment depends on age, stage, and severity and varies by clinician and case.

Compared with surgery

Surgical options (when considered) may aim to improve containment, address deformity, or improve mechanics.
Surgery can change biomechanics, but it is not a universal requirement and is typically considered in selected scenarios based on imaging and functional limitations. Risks, timing, and expected benefit vary by clinician and case.

Compared with other diagnoses (important look-alikes)

SCFE often presents in older children/adolescents with limp and limited internal rotation, but it is a different disorder involving slipping at the growth plate and is managed differently.
Hip infection (septic arthritis) and some inflammatory conditions can present with pain and limited motion and may need urgent evaluation.
Hip dysplasia affects socket coverage and can influence hip mechanics; it is evaluated with specific imaging features distinct from Perthes patterns.

Bilateral Perthes disease Common questions (FAQ)

Q: Does Bilateral Perthes disease cause pain in both hips?
It can, but symptoms are variable. Some children have pain on one side even when imaging shows changes in both hips. Pain may also be felt in the thigh or knee due to referred pain pathways.

Q: Is Bilateral Perthes disease the same as avascular necrosis?
Perthes disease is a childhood form of avascular necrosis affecting the femoral head, usually without an identified single cause. “Avascular necrosis” is a broader term that can apply to different ages and different underlying causes.

Q: How is Bilateral Perthes disease diagnosed?
Diagnosis typically combines a clinical exam with imaging. X-rays are commonly used, and MRI may be used when early changes are suspected or to better define involvement. The exact workup varies by clinician and case.

Q: How long does Bilateral Perthes disease last?
The active and healing phases often span months to years. The timeline depends on the stage at diagnosis, how much of the femoral head is involved, and individual healing patterns. Clinicians commonly describe the course in phases rather than a fixed duration.

Q: Is it “safe” to keep walking or playing sports with Bilateral Perthes disease?
Safety and activity choices depend on symptoms, hip motion, and disease stage, and recommendations vary by clinician and case. In general, clinicians weigh pain levels, limp, range of motion, and imaging findings when discussing activity participation.

Q: Will my child need surgery if both hips are involved?
Not always. Some cases are managed without surgery, while others may be considered for operative options based on age, severity, and hip shape. Decisions are individualized and depend on clinician assessment and imaging over time.

Q: What is the recovery like if surgery is used?
Recovery expectations depend on the procedure type, which can differ substantially. Many surgical pathways involve a period of restricted activity and structured rehabilitation, with follow-up imaging to assess healing and alignment. Specific timelines vary by clinician and case.

Q: Can adults get Bilateral Perthes disease?
Classic Perthes disease refers to childhood onset. Adults can have hip osteonecrosis or can have residual deformity from childhood Perthes that becomes symptomatic later. Clinicians distinguish these scenarios because evaluation and management goals differ.

Q: Does Bilateral Perthes disease increase the chance of arthritis later?
Residual femoral head deformity can alter hip mechanics, which may increase the likelihood of impingement and degenerative changes over time. However, long-term outcomes vary widely, and some people maintain good function depending on final hip shape and lifetime joint loading.

Q: How much does evaluation and treatment cost?
Costs vary widely by region, clinic, imaging needs (X-ray vs MRI), therapy, and whether surgery is considered. Insurance coverage, facility billing practices, and follow-up frequency can also change overall cost. For individualized estimates, clinicians’ offices typically provide billing guidance.