Legg-Calve-Perthes disease (LCPD) is idiopathic osteonecrosis or idiopathic avascular necrosis of the capital femoral epiphysis of the femoral head. This condition was described independently by Arthur Legg, Jacques Calve, and Georg Perthes in 1910. This process is also known as coxa plana, Legg-Perthes, Legg Calve or Perthes disease.
The cause of Legg-Calve-Perthes disease is not known. It may be idiopathic or due to other etiology that would disrupt blood flow to the femoral epiphysis such as trauma (macro or repetitive microtrauma), coagulopathy, and steroid use. Thrombophilia is present in approximately 50% of patients and some form of coagulopathy is present in up to 75%.
Legg-Calve-Perthes disease usually occurs between the ages of 3 to 12 years old, with the highest rate of occurrence at 5 to 7 years. It affects 1 in 1200 children under the age of 15. Legg-Calve-Perthes disease occurs most commonly in male patients, with a male to female ratio between 4:1 and 5:1. It is bilateral in 10% to 20% of affected cases. When it occurs bilaterally, it is usually asymmetrical and discovered in different stages of the disease. If it is symmetrical, the examiner must consider multiple epiphyseal dysplasias as the culprit. Caucasians and Asians are more commonly affected. It is also more prevalent in urban areas in patients with lower socioeconomic status. Risk factors for Legg-Calve-Perthes disease include:
Ten percent familial (there is a delayed bone age by about 2 years)
HIV (Up to 5% of HIV patients have avascular necrosis of the hip)
Factor V Leiden and other inherited coagulopathies
Thrombophilias (increased clotting)
Hypofibrinolysis (decreased ability to dissolve clots)
Secondhand smoke exposure (OR=5)
Low socioeconomic status
Birth weight less than 2.5 kg in boys
Typically, Legg-Calve-Perthes disease includes four phases:
Necrosis: Disruption of the blood supply leads to infarction of the femoral capital epiphysis, particularly the subchondral cortical bone. Subsequently, this leads to a cessation of growth of the ossific nucleus. The infarcted bone softens and dies.
Fragmentation: The body reabsorbs the infarcted bone.
Reossification: Osteoblastic activity takes over, and the femoral epiphysis reestablishes.
Remodeling: The new femoral head may be enlarged or flattened. It reshapes during growth. Those that respond to conservative treatment will usually show healing in 2 to 4 years.
History and Physical
History May Uncover
Limp of acute or insidious onset, often painless (1 to 3 months)
If pain is present, it can be localized to the hip, or refer to the knee, thigh, or abdomen
With progression, pain typically worsens with activity
No systemic symptoms should be found
Physical Examination May Reveal
Decreased internal rotation and abduction of the hip
Pain on rotation referred to the anteromedial thigh and/or knee
Atrophy of thighs & buttocks (from pain leading to disuse)
Leg length discrepancy
Antalgic Gait (acute): Short-stance phase secondary to pain in the weight-bearing leg
Trendelenburg gait (chronic): Downward pelvic tilt away from affected hip during the swing phase
High Index of Suspicion
Labs are used to exclude other diagnoses (complete blood cell count, ESR within reference range)
Early radiographs can be normal
Plain films are preferred
Standard anteroposterior pelvis and frog-leg lateral (Lauenstein) views
If in doubt or plain films are normal, try a bone scan or MRI
Widening of joint space (epiphyseal cartilage hypertrophy)
Changes in the epiphysis (smaller, appears denser)
"Crescent sign:" subchondral radiolucent zone of the anterolateral epiphysis (subchondral fracture)
Flattening of the femoral head, fragmentation, healing (sclerosis)
Bone scans show decreased perfusion to the femoral head
MRI shows marrow changes suggestive of Legg-Calve-Perthes
Treatment / Management
Goals of treatment include pain and symptom management, restoration of hip range of motion, and containment of the femoral head in the acetabulum.
Indicated for children with bone age less than 6 or lateral pillar A involvement
Activity restriction and protective weight-bearing is recommended until ossification is complete
The patient may still take part in physical therapy
Literature does not support the use of orthotics, braces or casts
NSAIDs can be prescribed for comfort
Referral to an experienced pediatric orthopedist is recommended
Good outcomes reported in up to 60% of patients
Femoral or Pelvic Osteotomy
Indications: children older than 8 years
Lateral pillar B and B/C have improved outcomes with surgery compared to A and C
Studies suggest early surgery before femoral head deformity develops
Valgus or Shelf Osteotomies
Indications: children with hinge abduction
Improves abductor mechanism
Emerging modality for treating mechanical symptoms and/or femoroacetabular impingement
Differential diagnoses that must be considered given the radiographic findings include:
Infectious etiology including septic arthritis, osteomyelitis, pericapsular pyomyositis
Multiple epiphyseal dysplasia (MED)
Spondyloepiphyseal dysplasia (SED)
Sickle cell disease
Multiple classifications can be utilized to describe Legg-Calve-Perthes disease. The lateral pillar, or Herring, classification is widely accepted with the best interobserver agreement. It is generally determined at the beginning of the fragmentation stage, approximately 6 months after initial symptom presentation. It cannot be used accurately if the patient has not entered the fragmentation stage radiographically. The goal is to provide prognostic information. This classification is based on the height of the lateral pillar on the AP X-ray image.
Group A: The lateral pillar is at full height with no density changes. This group has a consistently good prognosis.
Group B: The lateral pillar maintains greater than 50% height. There will be a poor outcome if the bone age is greater than 6.
Group C: Less than 50% of the lateral pillar height is maintained. All patients will experience a poor outcome.
Age at Onset
Usually younger age at diagnosis equals a better outcome.
Patients less than 6 years old may develop a normal hip joint.
Patients older than 6 years may have continued pain and subsequent arthritis.
Lateral Pillar Classification (degree of femoral head involvement: A [least] to C [most])
Patients more than 8 years old and patients in lateral pillar group B or B/C (border group) do better with surgery than with nonoperative treatment.
Patients less than 8 years old and patients in group B do well regardless of treatment choice.
Patients in group C experience poor outcomes regarding hip condition, regardless of treatment choice.
Fifty percent of patients almost fully recover, with no long-term sequelae
Pain and Disability
Fifty percent of patients develop pain and disability in their 40s and 50s, and degenerative joint disease leading to hip replacement in their 60s and 70s.
Female patients have worse prognoses than male patients if onset occurs at more than 8 years of age.
As Legg-Calve-Perthes disease progresses, various deformities of the femoral head can develop. The most common are coxa magna (widening of the femoral head) and coxa plana (flattening). If the femoral head is damaged, it can result in premature physeal arrest which can lead to leg length discrepancy. A poorly formed femoral head can also lead to acetabular dysplasia and resultant hip incongruency. This can lead to altered mechanics and subsequent labral tears. Lateral hip subluxation or extrusion is a complication associated with a poor outcome and can lead to lifelong problems for the patient. A late complication of this childhood disease is hip arthritis.