In Switzerland, orthopedic surgeons have been working for years to develop and perfect a total ankle replacement referred to as the Scandinavian Total Ankle Replacement (STAR). This is a fairly new system and very favorable early to mid-term results have been published.
But according to a recent report from a group of Scandinavian surgeons, the long-term results are not as positive. It appears that over time, there are more and more implants that develop problems. In their experience, the need for a second (revision) surgery increased after 10 years and continued to increase as time went by.
The main reason for implant failure was loosening. Degenerative changes where the implant and bone connected (called the prosthesis-implant interface) was observed. The cause of this degenerative process may be the coating used on some of the component parts of the implant. A single layer of hydroxyapatite was used. Hydroxyapatite can be found in teeth and bones and is commonly used as a coating to promote bone ingrowth into prosthetic implants. It seems the body tends to resorb the coating so that over time, it weakens and then comes off the implant. Then the implant loosens and pulls away from the bone.
Other problems observed with the STAR system included the formation of bone within the surrounding soft tissues (a condition known as heterotopic ossification), bone cysts, residual pain, and loss of motion.
Three-fourths of the patients in this later follow-up complained of ongoing pain and ankle motion was limited to about 24 degrees (less than one-third of normal). Surgeons say that improved ankle motion isn’t the main goal of the surgery and patients shouldn’t expect full or normal motion. Instead, pain relief and saving the ankle joint are the main goals. Without the ankle replacement, the joint would have to be fused resulting in complete loss of motion.
But despite low functional outcomes, patient satisfaction remains high. The same level of patient satisfaction has been reported in other studies where function was progressively worse over time.
Anyone who has any type of joint replacement (including ankle) and continues to experience residual pain should return to the surgeon for a follow-up evaluation. There may be a simple solution to your cousin’s pain that could be addressed. More complex problems may require a second surgery but that cannot be determined without further assessment.