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:
Typically, Legg-Calve-Perthes disease includes four phases:
History May Uncover
Physical Examination May Reveal
High Index of Suspicion
Labs are used to exclude other diagnoses (complete blood cell count, ESR within reference range)
Goals of treatment include pain and symptom management, restoration of hip range of motion, and containment of the femoral head in the acetabulum. 
Femoral or Pelvic Osteotomy
Valgus or Shelf Osteotomies
Differential diagnoses that must be considered given the radiographic findings include:
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.
Age at Onset
Lateral Pillar Classification (degree of femoral head involvement: A [least] to C [most])
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.
LCPD has no cure and the disorder is best managed by a multidisciplinary team that also includes the orthopedic nurse. LCPD is associated with high morbidity if the diagnosis is missed or delayed. For children with mild disease, non-surgical treatment is recommended with activity restriction and protective weight-bearing until ossification is complete. Clinicians should know that the current literature does not support the use of orthotics, braces or casts. To improve patient outcomes, all cases should be referred to a pediatric orthopedic surgeon as soon as the diagnosis is made.
These patients need long follow up as deformities of the femoral head can develop. Arthritis is not an uncommon complication in childhood.
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