Hip Surgery for Sanfilippo Syndrome
The following will give you some idea of why surgery may be necessary and what it may involve.
Why might hip surgery be necessary?
For some patients, Sanfilippo can cause a variety of issues related to the hips, which may result in pain and difficulty walking.
It is uncertain exactly how the disease causes issues with the bones, but some scientists think that it is related to the accumulation of heparan sulfate and possibly dermatan sulfate in bones. Both of these molecules belong to a group called glycosaminoglycans (GAGs). These GAGs may affect the function of both osteoclasts — the cells that break down bone — and chondrocytes, the cells that make up cartilage. They also may affect the growth plates on the ends of bones.
Painful dysplasia may occur in Sanfilippo patients. This is when the head of the upper leg bone, called the femur, doesn’t fit together well with the hip socket (acetabulum). The condition can lead to dislocations.
Researchers estimate that anywhere from 18% to nearly 50% of Sanfilippo patients have some form of hip dysplasia. In these patients, the acetabulum is usually formed correctly but the femoral head may be deformed or the angle at which the head is attached to the leg bone may be too great.
Osteonecrosis of the femoral head
Another cause of hip pain in Sanfilippo syndrome patients is osteonecrosis of the femoral head, or the deterioration of the top of the upper leg bone. This generally occurs when the blood flow to the top of the leg bone is disrupted, leading to the death of bone cells. Researchers estimate that osteonecrosis of the femoral head occurs in about 24% of Sanfilippo patients.
As with hip dysplasia, osteonecrosis of the femoral head is more likely to occur in patients who have more severe disease.
What does the surgery involve?
While physicians usually treat the pain associated with hip dysplasia or osteonecrosis of the femoral head with steroid injections, it may be necessary to perform surgery in extreme cases. This may involve the removal of the femoral head or total hip replacement.
In either surgical option, the patient first will be put under general anesthesia. The surgeon then makes an incision in the skin of the affected hip(s) and surgically removes the damaged or deformed pieces of bone and cartilage from the end of the femur, and possibly the hip socket. If the patient is already a wheelchair user, the surgery may end at that point.
This limited surgery is for patients who won’t be walking again but require pain relief. In such a procedure, the surgeon just removes the head of the femur so it no longer causes pain.
If the goal is to replace the hip, usually for mobile patients, the surgery may continue. In such cases, the surgeon would then insert pieces of a prosthetic joint into the hip and femur to make a new joint. Following the prosthetic implant, the doctors will suture the patient’s incisions and send them to recovery.
What are the risks of hip surgery?
All surgeries involve risks, even for healthy people. Generally, these risks include blood clot formation, infections, and fractures of the bones. Patients with Sanfilippo also are at increased risk of airway obstructions during anesthesia. However, there are ways to minimize this risk.
Your healthcare team should meet with you to explain the procedure and answer all of your questions if you are considering surgery for hip pain.
Last updated: Sept. 29, 2020
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