Spasticity (increased muscle tone) is common with cerebral palsy and can cause the muscles to pull unevenly on the hip. Over time, as the child grows and the muscles remain short and tight, the head of the femur (thigh bone) is forced out of the hip socket.
Often the hip socket (called the acetabulum) is shallow and not fully developed. This is especially common in children with cerebral palsy (or other neurologic conditions) that prevent them from standing up and walking. Walking puts pressure through the thighs into the hips and helps form the acetabulum (hip socket) and shape the femoral head that fits into the socket.
When the femoral head shifts out of the hip socket, surgery is done to reconstruct the hip and form a new, deeper socket. There are a number of different ways to do this. The procedure isn’t always successful but there are many reasons for a less than optimal outcome.
For example, what is the shape of the hip socket and where are the weak areas where the femoral head can push past the cartilage and pop out? This question must be answered when planning surgery to reconstruct the hip.
If it’s not addressed, then the same problem can happen again after surgery. There could be instability at the top of the socket (superior direction). This superior deficiency could be more toward the front (anterior) or more toward the back (posterior) part of the hip.
Then again the instability or deficiency could be multidirectional (present in more than one direction). The problem is really more complicated than that. In many cases, normal growth and development of the bones is altered in these children by the change in muscle pull and biodynamics.
For example, the femur may twist or tilt thus placing the head of the femur in the socket at an angle. Likewise, any change in the shape or orientation of the pelvic bones that form the upper part of the hip socket can have an impact on alignment.
Even with a perfect surgical result, if the child grows rapidly and the muscle tone increases even more, dislocations and deformities can occur. A second surgery is not uncommon — in fact, many children with cerebral palsy have multiple different surgical procedures as they grow and mature.
If you have any doubts about your daughter’s care, there’s nothing wrong with seeking a second opinion. If you don’t feel comfortable consulting with someone else in the same orthopedic practice, then ask your pediatrician for an alternate choice. The decision to have another surgery for your daughter is a major one and one that deserves a careful evaluation of what’s best for her.