Legg Calve Perthes disease is a developmental disease of the hip. It starts in late childhood and finishes its course by late childhood. It leads to a deformity of the femoral head. In later life this deformity may give rise to secondary osteo-arthritis of the hip.
The blood supply to the growth plate in the femoral head is compromised and deficient. Hence the bone undergoes necrosis and breaks down. This is a gradual process occuring over several weeks. As blood supply returns, the bone regenerates and reforms. This may take upto three years. It may result in a deformity of the femoral head. The rounded femoral head becomes flattened and mushroomed. Recent evidence indicates that it may be due to a defect in the clotting mechanism with a tendency to clot formation in the arterioles of the femoral head.
Sometimes it may present with knee pain.
A limp is noticed.
As pain persists, it may lead to wasting of the gluteal and thigh muscles.
AP and frog lateral x rays of the affected hip are done. In early cases, an MRI may show the lesion before collapse occurs. Transient osteopenia is a radiological sign that may suggest early Perthes disease.
In early stages, weight bearing is restricted by short period of rest. A short period of traction may reduce spasm and give pain relief. When the diagnosis has been confirmed, the congruity and containment of the hip is determined by hip arthrography. If the hip is contained, then bracing is sufficient. The leg is positioned in abduction and internal rotation.
If there is a tendency to subluxation, osteotomies are done to regain containment. A femoral varus and derotation osteotomy is a common procedure.
Acetabular ostotomies are Salter's, Chiari and Pemberton osteotomies.
When the diagnosis is delayed and deformity of the head has occured, then it is left alone. Hip arthrodesis is an option. In adult life, hip replacement is done. The indication for a hip replacement are pain, shortening and deformity.
Hip replacement in these patients is done with durable materials like ceramic, metal. Hip resurfacing is not indicated in this condition as the bony anatomy is abnormal.