Perthes disease, also known as Legg-Calve-Perthes disease, or coxa plana, is a hip disorder that disrupts the blood supply to the femoral head, the ball-like part of the hip joint. This interruption in circulation causes the bone to undergo necrosis (die) and become weak.
Perthes is often misunderstood as a single disease, but it is actually a complex, multi-stage process that unfolds over several years. Initially, the blood supply to the femoral head is disrupted, causing the bone to weaken and eventually collapse. As time passes, the body restores the blood flow to the femoral head, which allows the bone to begin healing and regrow. However, this recovery is not immediate and can take several years to complete, with the bone slowly regaining its structure and strength. The condition’s stages can vary, making it a prolonged and sometimes unpredictable journey for affected children.
Perthes disease progresses through four key stages, each crucial to understanding the condition’s impact on the hip joint. The first stage, necrosis, sees the interruption of blood flow to the femoral head, leading to bone cell death. This stage can be painful, and symptoms such as limping and altered walking patterns emerge. It can last for several months and often presents with significant inflammation. The second stage is fragmentation where the body replaces dead bone with softer, weaker bone, and the femoral head may flatten. In the third stage, reossification, new, stronger bone develops in the femoral head, often lasting the longest. Lastly, the bone regrows, and the femoral head assumes its final shape, which depends on the extent of damage and the child’s age.
Children with perthes disease typically develop a noticeable limp due to the pain and stiffness in the hip joint. The pain, which can occur in the groin, thigh, or knee, is often mild but becomes more intense with physical activity. Perthes disease can lead to shortening of the affected leg, causing uneven leg length. This condition most commonly affects children between 3 and 11 years.
Surgery may be necessary for perthes disease, especially when non-operative treatments, such as physical therapy or casts/braces, aren’t sufficient. The goal of treatment for Perthes is to help the femoral head regrow into a rounded shape that fits the acetabulum, ensuring normal hip movement. Surgery may be required to reshape the bone in the hip socket, osteotomy, or reshape the hip socket through arthroplasty.