Three years ago, I had a total ankle replacement for a rheumatoid arthritic ankle. According to my X-rays, it looks like the implant is starting to sink down into the bone. I'm going to be seeing a specialist but what can be done about this?

Loosening or sinking of the implant are the two most common reasons for total ankle replacement (TAR) failure. Subsidence is the medical term to describe sinking of the implant deeper into the bone.

Studies done on the intermediate to long-term results of TAR have been done. Researchers who have reviewed the data say it looks like as many as 28 per cent of TARs require revision for these two problems. Revision surgery may mean the current implant is removed and a new one put in its place.

Removing and replacing the implant is the most likely plan of action for a prosthesis that has come loose. Subsidence may require fusion to stabilize the joint. Changes in bone density from osteoporosis or changes in bone quality from osteopenia may mean the bone can't support an implant of this type.

Seeing a specialist is the right step in finding out the best treatment plan for you. After taking a history and review of your records, X-rays and other imaging studies may be ordered. You may have several options to consider depending on all the various factors. The orthopedic surgeon will be able to advise you and answer any further questions you may have.