Perthes disease, most commonly referred to as Legg-Calvé-Perthes disease (LCPD), is known also as coxa plana or ischemic hip necrosis. LCPD is osteonecrosis (bone death) of the hip (femoral head, ball portion of ball-socket joint) that occurs in children due to temporary loss of blood to the hip region. The femoral head then dies in response to the insufficient, blood supply. According to the National Osteonecrosis Foundation (NONF), LCPD affects about 1 in 1200 children, and diagnosis typically occurs somewhere between 2 and 12 years of age. LCPD is five times more common in boys than girls.
First
The American Academy of Orthopedic Surgeons (AAOS) specifies that this disorder is a process of stages rather than a true "disease." LCPD has four stages. Multiple x-rays will be taken during the course of LCPD to monitor the stages; also, this disorder is diagnosed by x-ray technology.
In the first stage, according to the NONF, x-ray reveals sections of the femoral head as appearing more dense, which follows from initial blood insufficiency and necrosis. The joint is very unstable during this stage, and the potential for bone fracture with fragmenting bone exists. Also, irritation of the hip joint area can lead to an inflamed synovial membrane of the joint, resulting in increased fluid with synovitis. (See the Medline Plus link in Resources for an image).
Second and Third
The second stage involves osteo-fragmentation (bone fragmentation) of the femoral head area as seen on x-ray. This fragmentation stage frequently is associated with diagnosis of the disorder. Specifically, symptoms such as limping, pain in the knee, thigh or groin, as well as joint stiffness and restricted range of motion are pronounced. Also, the legs may look unequal in length, for the affected side may be shortened. Following the process of femoral head collapse, the body begins the process of reabsorbing the dead bone material. (See AAOS link in Resources).
Reossification is the third stage. Consistent blood flow returns, which supports the start of new bone growth. During this stage the femoral head begins to reform and the round ball-like head will reshape itself.
Fourth
The final stage is the healing stage. The collapsed and fragmented area of the femoral head (due to bone necrosis) completes the healing and reshaping processes with new bone. These stages, ending with new bone replacing the necrotic, dead bone cells, occurs over an estimated period of two to three years
