What is Legg-Calvé-Perthes disease?
In the growing child, the two major components of the hip joint are the ball (femoral head) and the socket (acetabulum). Legg-Calvé-Perthes disease, or Perthes disease, is a childhood hip condition in which the ball-shaped head of the thigh bone (femoral head) loses its blood supply and collapses. When this happens, a part or all of the area involved temporarily dies. It is important to understand that the acetabulum (socket) is not affected or involved in this loss of blood supply. The body will absorb the dead bone cells and replace them with new bone cells. The new bone cells eventually reshape the femoral head of the thigh bone. Legg-Calvé-Perthes disease causes the hip joint to become painful and stiff. It can also leave the femoral head deformed and lead to disability.
The femoral head in the growing child has several distinct zones:
- The metaphysis is the spongy bone area in the femoral neck or that portion of bone next to the femoral head.
- The physis is the growth center of the femur (thigh bone) and is composed of bone forming cells that enable the bone to grow in length.
- The epiphysis is located between the physis and the acetabulum (socket), and it actively contributes to the growth of the femoral head (ball portion).
Perthes disease goes through four phases:
- Phase 1: Blood stops reaching the femoral head, and the hip joint becomes inflamed, stiff and painful. Portions of the bone turn into dead tissue. The ball of the thigh bone becomes less round. This phase can last from several months up to one year.
- Phase 2: The body cleans up the dead bone cells and replaces them with new, healthier bone cells. The femoral head begins to remodel into a round shape again. The joint is still irritated and painful. This phase can last from one to three years.
- Phase 3: The femoral head continues to model itself back into a round shape with new bone. This phase lasts for one to three years.
- Phase 4: Normal bone cells replace the new bone cells. This last phase can last a few years to complete the healing process.
It is important to understand that every affected child goes through each phase, from beginning to end. This whole process can extend over many months to years.