Perthes disease is a rare disease that affects the hips of children, 4 to 10 years old. It is also called Legg-Calve-Perthes disease after the names of the three doctors who described the condition.
In this disease, the blood supply to the head of the femur (thigh bone) is temporarily interrupted for an unknown reason leading to death of the bone in this femoral head. The dead bone of the head may become deformed causing pain and limited movement of the hip joint. The blood supply then returns by time, and the bone heals, but the deformity of the head may not be fully corrected. The amount of residual deformity in the femoral head will determine the extent of trouble the child will have later in life.
Perthes disease passes through 4 stages:
- Necrosis: the blood supply to the head is disrupted leading to bone death. This leads to pain and limping. This stage may last for few months.
- Fragmentation: the body removes the dead bone and replaces it with softer bone. During this stage the head may collapse and deform.
- Reossification: stronger bone is formed. This stage can last for few years.
- Healed: bone regrowth is complete and the head assumes its final shape.
- Pain in the hip or groin, and sometimes referred to the knee.
- Pain increases with activity and is relieved by rest.
Clinical examination of the hip joint may reveal limited range of motion. X-ray will show the deformed femoral head and help the doctor determine the stage of the disease.
Treatment aims at relieving the pain, and protecting the shape of the femoral head, and restoring hip movement. If the diseases is not treated, the femoral head can deform and not fit properly in the acetabulum. This may lead to complications later in life such as hip arthritis.
In children below the age of 6 years, there is a good potential for healing of the bone. Thus, observation is sufficient for managing these children. Pain may be treated by simple non-steroidal anti-inflammatory drugs e.g. ibuprofen. In severe cases bed rest and crutches may be required. The children are advised to avoid high impact sports e.g. jumping, football, ….
Surgery is more likely to be required if the disease occurs in children above the age of 8 years, as these children are more prone to develop deformity of the femoral head.
The common surgery is an osteotomy, where the thigh bone (femur) is cut and repositioned to keep the femoral head fitting in the acetabulum. The bone is held in place by screws and plates, which will be removed later.