Last year, Canadian doctors performed more than fifty-seven thousand knee replacements according to the Canadian Institute for Health Information. That's up more than twenty percent from just five years ago.
Two recent studies have called this popular operation into question. Researchers concluded that far too many patients get new knees when they don't need them. Knee replacements should only be done on patients with severe arthritis, those with with bad knee pain and difficulty bending the knee, climbing stairs, getting in and out of a chair and walking without a cane or a walker. In one study, researchers at Virginia Commonwealth University in Richmond used an assessment tool to judge if the surgery was done on appropriate patients. Out of just over two hundred patients, a third got the surgery even though their arthritis wasn't severe.
A second study by the same researchers in Richmond looked at the long-term results in one-hundred-and-sixty-seven patients who had knee replacements. For the two thirds of the patients who were good candidates for knee replacements (bad knee pain and trouble bending the knee and getting in and out of a chair) their pain was much less after the operation. They could do things like walk and bend the knee much better than before the operation. Two years later, they continued to benefit from surgery.
However, people with mild arthritis were no better than before at things like bending the knee and walking around, In other words, the surgery was a waste of time. The reason is that for patients with mild to moderate arthritis, there's no measurable improvement to be had from a knee replacement. If you don't have much pain to begin with, then you don't have pain that can be relieved by the surgery. If both before and following surgery you walk well and can do good knee bends, then that means the surgery did nothing to improve your ability to function. In other words, people with mild to moderate arthritis don't get measurably better because they have less reason and less room to improve. The other important implication of the study is that at this point, while knee replacement surgery helps people with bad arthritis, there is little evidence the operation prevents severe arthritis later on.
Remember that knee replacements do help patients with severe arthritis. As our population ages, we should be seeing year-over-year increases in the number of patients with bad arthritis who would benefit from surgery. However some orthopaedic surgeons may not be good at selecting the most appropriate patients for knee replacements. Maybe they aren't using evidence-based guidelines on selecting patients. Evidence notwithstanding, perhaps they believe that a patient doesn't need a new knee now but will in two years and what's the harm in getting it done now while the patient is younger and healthier? Perhaps the surgeon knows when the operation won't help but just can't say no to the patient who insists.
Knee replacements are best suited for patients age sixty-five and older who have severe arthritis -- people with severe pain that limits their ability to walk and do things with their knees most of us take for granted. If you're in doubt, ask your doctor how bad your arthritis really is. Your x-rays should show bone on bone arthritis meaning knee cartilage has completely worn away. Some orthopaedic surgeons have recognized that they are good at doing surgery and not so good a picking the most appropriate patients for surgery. What they're doing is recruiting advance practice physiotherapists - physios with extra training - who are good at choosing who should have the operation now and who does better putting surgery off and doing things like exercises, losing weight and taking Tylenol instead.