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I just found out my shoulder replacement is coming loose. I can't begin to think what I might have done to cause this. I followed every instruction of my surgeon and my physical therapist. I have been just fine for eight years and now this. The surgeon offered no explanation for this happening. What can you tell me?

Shoulder replacements are wonderful inventions. They help restore pain free shoulder and arm motion. Patients are almost always fully satisfied with the results. But from the surgeon's point-of-view, the results aren't always 100 per cent acceptable. Complications can occur such as joint infection, dislocation, or nerve injury. Problems with the implant including loosening and subsidence (sinking down into the bone) also occur more often than they would like. The results of a recent study from Germany may help offer some clues to the loosening you are experiencing. One surgeon followed 39 of his patients for 10 to 15 years and reported on the long-term results. He used the same third-generation cemented total shoulder replacement in each patient so that results could be compared directly. Pain, shoulder range-of-motion, and X-ray findings were the main measures of outcomes. Third generation refers to the number of times the implant has been redesigned, revised, and improved. In all cases, pain, range-of-motion and function improved. And along with those results were consistent reports of patient satisfaction. Loosening of the glenoid component (socket side of the implant) occurred in 36 per cent of the group. Despite the loosening, the implant remained intact and the patients still had good, pain free motion. Reasons for the high rate of loosening were explored. Possible risk factors include: the design and shape of the glenoid component, surgical technique (removing too much of the arthritic bone before putting the implant in place), and cementing technique. It is also possible that there are some as yet unknown patient factors. No one developed any loosening of the humeral component (round ball that fits into the socket at the top of the upper arm bone). So that draws the attention back to the glenoid (socket side) part of the implant. Younger patients tend to develop loosening more often than older adults, so maybe a higher activity level is part of the picture. And then there is always the possibility that some aspect of the postoperative protocol (either right after surgery or during rehab) that could be a contributing factor. These are all variables that must be evaluated more closely in future studies.

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