Legg-Calvé-Perthes disease (Perthes) is a rare disease that most often affects boys between the ages of 2 and 12. Girls can have LPD. The hips are the main problem. Sometimes both hips are involved, but usually only one side is affected.
With Perthes, blood flow to the ball of the hip is stopped and bone death (necrosis occurs. As necrosis spreads, the ball develops a fracture of the supporting bone. This fracture signals the beginning of bone reabsorption by the body. As bone is slowly absorbed, the body tries to replace it with new tissue and bone.
Degenerative osteoarthritis can occur with age in adults with Perthes. It seems to depend on two things. If the ball reshapes itself and fits into the socket, arthritis is usually not a concern. If the ball does not reshape well, but the socket’s shape still conforms to the ball, mild arthritis occurs in later adulthood. A flattened ball and shallow socket create the most significant problems later.
Total hip replacement is a challenge because of the odd shape of the hip and leg length differences. The surgeon must work around multiple different deformities affecting the femoral head and hip socket. Changes in the bone and soft tissues around the hip as a result of previous surgeries can also be a problem. Disruption of bone growth often results in a short femoral neck. Scar tissue can pose some technical pitfalls.
These challenges have not kept surgeons from trying to improve the total hip replacement procedure for patients with Pethes who develop secondary hip osteoarthritis. With some creative modifications (aligning femoral stems and placing cups on the socket side at just the right angle), it is possible to restore good hip biomechanics.
Hip resurfacing arthroplasty is a type of hip replacement that replaces the arthritic surface of the joint but removes far less bone than the traditional total hip replacement.
Because the hip resurfacing removes less bone, it may be preferable for younger, more active adults. A good candidate for joint resurfacing is someone who may need a second, or revision, hip replacement surgery as they grow older and wear out the original artificial hip replacement.
There haven’t been very many studies reporting long-term results following joint resurfacing for patients with Perthes disease. Surgeons are exploring this management approach because it saves bone, and increases hip motion. Converting to a total hip replacement later is also possible.
The downside may be that hip resurfacing won’t be able to restore normal joint biomechanics. If there is a leg length difference from childhood, then a hip replacement may be a better choice. Hip resurfacing can’t even out the length differences whereas a hip replacement can even out some of the difference.
Likewise, deformities of the hip aren’t as easily handled with joint resurfacing. You may end up having more than one surgery if things don’t work out as expected. The decision isn’t an easy one. Your surgeon is the best person to advise you. X-rays, CT scans, and other imaging studies may help shed some light on what is possible based on the shape and severity of any hip deformities.