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I had a total disc replacement done at L34 about six months ago. The X-rays show the implant has started to sink down into the vertebral bone. What can be done about this?

Subsidence is the term used to describe this problem. It can occur whenever an implant of any kind is used in the body. The reason why subsidence occurs isn't entirely clear yet.

It may be understandable in patients who have changes in the bone such as osteopenia or osteoporosis. But it can happen to patients without these problems as well. And with a total disc replacements, the implant design may be at fault. Subsidence seems to occur more often with implants that have a central keel to hold them in place. Studies are ongoing to find out what can be done to prevent this and other problems.

Treatment varies depending on many factors. Careful observation may be all that's needed when the patient doesn't have any symptoms. But there are several options for the patient with severe back pain. First, the implant can be removed and replaced with another implant. Or it can just be taken out and spinal fusion done instead.

Vertebroplasty has been used by some surgeons to prevent further sinking of the device. A long, thin needle is inserted into the disc area. Glue is injected through the needle to help support the area. The glue dries and acts like cement.

The problem of TDR subsidence is fairly new and doesn't happen very often. A clear solution hasn't been determined yet. Each surgeon may approach the problem based on the individual patient and his or her circumstances.

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