What causes Perthes disease? The cause is unknown and the disease is not inherited in most patients. A very small number of patients have another family member with Perthes. Should I expect a lot of complaints of pain? Pain generally suggests that there is hip joint inflammation, which can be caused by too much activity. The amount of pain experienced by a child with Perthes disease varies from patient to patient. Some patients complain of activity-related pain or night pain only. Your child may complain of groin, thigh or knee pain. They may have restricted movement and a mild limp. You and your child’s doctor will discuss how to manage pain. What is the time frame of Perthes? Perthes disease has four stages. In general, it may take three to five years for a patient to go from the initial stage to the healed stage of the disease. The length