Perthes disease is a condition that affects the hip in children between the ages of four and eight. The condition is also referred to as Legg-Calvé-Perthes disease in honor of the three physicians who each separately described the disease.
In this condition, the blood supply to the growth center of the hip (the capital femoral epiphysis) is disturbed, causing the bone in this area to die. The blood supply eventually returns, and the bone heals. How the bone heals determines what problems the condition will cause in later life. Perthes disease may affect both hips.
Perthes disease results when the blood supply to the capital femoral epiphysis is blocked. There are many theories about what causes this problem with the blood supply, yet none have been proven.
Clearly the problem is one of blood loss called ischemia. The area affected most is the head of the femur (thigh bone). This has been confirmed with today’s modern imaging studies. As a result of this blood loss, the bone dies and starts to collapse. Soon the smooth, round head of the femur starts to
flatten and deform.
But what causes the decreased vascularity (blood flow) and can it be stopped before the damage is done? Many experts believe LCP is the result of several or even many factors. Another way to say this is that LCP is a multifactorial disease with both genetic and mechanical contributing factors.
On the genetic side, there are families with many members who have LCP as a result of a mutation in a particular gene. The affected gene controls the strength of collagen tissue. Collagen fibers are what make up all of the soft tissues in the body, including joint cartilage, ligaments, muscles, tendons, and blood vessels. One miscoding in the gene and the hip joint cartilage and its blood vessels don’t form correctly.
Another biologic factor that contributes to some cases of LCP is a protein deficiency. Without the proper sequencing of these important proteins, affected individuals have abnormal coagulation (blood clotting). Abnormal blood clotting can cut off blood supply to the femoral head.
With this much information in hand, further studies were done. Now there is some evidence that LCP can develop after a single episode of ischemia (blood loss) no matter what the cause. But the risk goes up with repeated (multiple) episodes of blood loss. If this proves to be true, then it is essential to predict, recognize, and stop all ischemic episodes.
Although Legg-Calvé-Perthes disease may sound like a simple problem, there’s still so much we don’t know about what causes it and how or why it develops. More and more, it’s looking like a complex biologic problem with multiple contributing factors and/or “triggers”. Hopefully, in time, scientists will be able to uncover important facts that can change treatment and results for those (like yourself) who have this condition.