1) Trauma and damage to the hip (blunt force trauma or repetitive cumulative damage)
2) congenital deformity (reduction in blood flow to the joint. It is thought that the artery of the ligamentum teres femoris closes too early, not allowing time for the medial circumflex femoral artery to take over).
This results in ischemic necrosis of the hip, coxa plana, osteochondritis and avascular necrosis of the femoral head.
Osteoarthritis may develop in adulthood.
Treatment and Symptom management:
Modern treatment focuses on removing pressure from the joint to increase blood flow, in concert with physiotherapy. Pressure is minimized on the hip through use of crutches or a cane, and the avoidance of running-based sports.
Pediatric Orthopedic and Scoliosis Center. Legg-Calve-Perthes Disease. Retrieved September 7, 2009 from http://childrensspecialists.com/body.cfm?id=513