Legg-Calve-Perthes disease (LCPD) or Perthes is a rare childhood hip condition. Perthes occurs when blood supply to the femoral head (ball) is temporarily disrupted. Without sufficient blood supply, the bone cells die (avascular necrosis) and the femoral head weakens and can fragment and/or become misshapen. Over time, blood supply is restored and bone begins to grow back and heal; however, the femoral head often remains misshapen and lead to ongoing hip pain, early onset hip osteoarthritis and/or necessitate the need for a hip replacement. The causes of Perthes disease are currently unknown.
There are four stages in Perthes disease:
Initial/necrosis – blood supply to the femoral head is disrupted and bone cells die. The area becomes intensely inflamed and irritated causing a limp or a different way of walking. The initial stage may last for several months.
Fragmentation – the body removes dead bone and replaces it with initial, softer bone (“woven bone”). Due to the weaker state of the bone, the head of the femur is more likely to break apart and collapse. This stage may occur for a period of 1 to 2 years.
Reossification – New, stronger bone develops and begins to take shape. The reossification stage is often the longest stage and may last for a few years.
Healed – Bone regrowth is complete and the femoral heal has reached its final shape. Roundness of the femoral head will depend on factors such as extent of damage that occurred during fragmentation phase and age of Perthes onset.
Perthes is a rare childhood hip condition and has a prevalence of 1 in 10,000 children.
Perthes typically occurs in children between the ages of 4 – 10 years but most commonly presents before the age of 8. It is five times more common in boys than in girls.
Other risk factors include:
-Family history of Perthes
-Low birth weight
-Abnormal birth presentation
-Second hand smoke
-High levels of activity
One of the earliest signs of Perthes is a change in walking and running style such as a limp. This is often most apparent during sports activities. Children with Perthes may also experience pain in the hip, groin, or other parts of the leg (thigh and/or knee) that may worsen with activities. Areas around the hip may also become inflamed and irritated and be accompanied with painful muscle spasms.
In some cases, a child may feel no symptoms and the condition may not be noticed and diagnosed until an x-ray is taken due to a fall or other injury.
Treatment for Perthes mainly focuses on preserving the rounded shape of the femoral head to fit into the socket of the hip joint, relieve painful symptoms, as well as restore hip movement. If left untreated, the femoral head can deform and not fit well within the hip socket, which may lead to hip problems in adulthood, such as early onset osteoarthritis. Treatment method will depend on a number of factors such as patient age, degree of damage to the femoral head, and age of onset.
Non-surgical approaches to treatment may include:
Anti-inflammatory medications – painful symptoms are caused by inflammation of the hip joint. Anti-inflammatory medicines can be used to reduce inflammation.
Activity restrictions– Avoidance of high impact activities such as running and jumping may help relieve pain and protect the femoral head
Casting or bracing– A cast or brace may be used to hold the position of the femoral head in the hip socket if a deformity is developing
Physical therapy–physical therapy exercises are recommended to help restore hip joint range of motion. Therapy regimens often focus on hip abduction and internal rotation exercises.
Movement aids – Crutches and wheelchairs can be used to reduce the amount of weight that is placed on the joint
Surgery is most often recommended when age of onset is after 8 years of age, more than 50% of the femoral head is damaged, or if non-surgical treatment methods have failed to keep the hip in the correct position for healing.
Surgical approaches to treatment may include:
Osteotomy – In this type of procedure, the bone is cut and repositioned to keep the femoral head within the acetabulum. Alignment is kept in place with screws and plates which are removed after the healed stage of the disease.
Femoral osteotomy– cutting of the femur bone to realign the joint
Pelvic osteotomy– cutting of the pelvic bones to make the socket deeper as the femoral head may have enlarged during the healing process and no longer fits within the socket
Following surgery, children are placed in a cast for 6 – 8 weeks to protect the alignment. After cast removal, physical therapy is often required to restore muscle strength and range of motion. Crutches or a walker may also be needed to reduce weight bearing on the affected hip.