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Figure 1. Anteroposterior radiograph of hip.
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Figure 2. Lateral frog-leg view of the hip.
A 5-year-old boy presents with right hip pain and limp that have been present for the past month. The patient’s mother noticed his symptoms and is concerned because the child did not sustain any obvious injury. The mother confirms that the child has not had any recent viral infection, fever, chills, or sweats. The child seems to be acting fine other than the limp and occasional complaints of hip pain. On physical examination, the patient has a mild decrease in hip abduction and internal rotation on the right side compared with the left side. He has no leg length discrepancy. Radiographs of the hip are taken (Figures 1 and 2).
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Radiographic images confirm collapse of the femoral head, which is consistent with a diagnosis of Legg-Calvé-Perthes disease (LCPD). The disease causes idiopathic avascular necrosis of the femoral head that generally occurs in children aged 5 to 8 years. The most common presenting symptoms are mild hip pain and a limp.
The natural course of the condition starts with sclerosis of the epiphysis, loss of epiphyseal height, fragmentation and fissuring of the epiphysis, collapse and fissuring, and finally new bone formation and healing. The course from symptom onset to resolution can last over a period of 2 to 4 years. Anteroposterior and frog leg lateral radiographs can be performed every 3 to 4 months to ensure the femoral head is contained in the acetabulum and to track the course of the disease. The amount of femoral head collapse correlates with outcome including the likelihood of developing a hip deformity and secondary osteoarthritis.
Age of symptom onset is a significant predictor of outcome as younger patients have more time to grow out of any residual deformities. Age of onset of younger than 6 years can be treated successfully with nonsurgical management (activity modification based on symptoms). Bracing and physical therapy are not necessary or helpful for improving outcomes in patients younger than 6 years without severe epiphyseal collapse. Age of onset between 6 and 8 years offers a less predictable course and surgical vs nonsurgical outcomes are comparable in this group. Patients with symptom onset at 8 years of age and older are more prone to femoral head and acetabular abnormalities and poor hip function. Surgery is often performed early in the course of the disease for these patients to minimize the risk of secondary degenerative arthritis.1,2
Dagan Cloutier, MPAS, PA-C, practices in a multispecialty orthopedic group in the southern New Hampshire region and is editor in chief of the Journal of Orthopedics for Physician Assistants.
References
1. Herring JA, Kim HT, Browne R. Legg-Calvé-Perthes disease: part II: prospective multicenter study of the effect of treatment on outcome. J Bone Joint Surg Am. 2004;86(10):2121-2134.
2. Kim HK. Legg-Calvé-Perthes disease. J Am Acad Orthop Surg. 2010;18(11):676-686. doi:10.5435/00124635-201011000-00005
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