Perthes disease involves disruption of blood flow to the femoral head, causing avascular necrosis of the bone. This affects the epiphysis of the femur, which is the bone distal to the growth plate (physis). The full name is Legg-Calvé-Perthes disease. It occurs in children aged 4 – 12 years, mostly between 5 – 8 years, and is more common in boys.
It is described as idiopathic, meaning there is no clear cause or trigger for the avascular necrosis. One theory suggests that repeated mechanical stress to the epiphysis may interrupt the blood supply.
Over time there is revascularisation or neovascularisation and healing of the femoral head. There is remodelling of the bone as it heals. The main complication is a soft and deformed femoral head, leading to early hip osteoarthritis. This leads to an artificial total hip replacement in around 5% of patients.
Perthes disease present with a slow onset of:
- Pain in the hip or groin
- Restricted hip movements
- There may be referred pain to the knee
There will be no history of trauma. If the pain is triggered by minor trauma, think about slipped upper femoral epiphysis, particularly in older children.
The initial investigation of choice in Perthes disease is an xray, however this can be normal.
Other investigations that can be helpful in establishing the diagnosis are:
- Blood tests are typically normal, particularly inflammatory markers that are used to exclude other causes
- Technetium bone scan
- MRI scan
The severity of Perthes disease varies between patients.
Initial management in younger and less severe disease is conservative. The aim of management to maintain a healthy position and alignment in the joint and reduce the risk of damage or deformity to the femoral head. This is with:
- Bed rest
Physiotherapy is used to retain the range of movement in the muscles and joints without putting excess stress on the bone.
Regular xrays are used to assess healing.
Surgery may be used in severe cases, older children or those that are not healing. The aim is to improve the alignment and function of the femoral head and hip.
Last updated January 2020