More and more younger adults (younger than 60 years old) are getting total knee replacements (TKRs). Severe, disabling pain from degenerative joint disease is the main reason given for this type of surgery. And early reports indicate great success so far — a survival rate of the implant that was 82.2 percent for the first 15 years.
But some experts have called that survival rate into question. There is some evidence that those statistics may not represent the whole picture. Dr. Andrew J. Price and associates conducted a study with much less favorable outcomes. The reason for the difference is the type of measurement used to define success.
Most surgeons use revision as the end-point of the implant’s life. Infection and loosening are the usual reasons an implant must be revised, removed, or replaced. But that’s a surgeon’s idea of failure. Patients are more likely to use pain as a gauge of success vs. failure.
And the results of Dr. Price’s study showed that most patients report at least moderate pain in the years following knee joint replacement. They aren’t pain free after all. Using revision OR pain as a criteria for the endpoint in implant survival, the rates fell to less than 60 per cent.
Dr. Price points out that revision (for any reason, not just infection or loosening) and pain are just two variables that can be used as an end-point in determining success versus failure of implants. There are others as well. For example, function such as walking, going up or down stairs, getting up and down off the floor, and even running could be used as measures of outcome in younger patients.
More study is needed to gather data on younger patients getting total knee replacements. Using only one measure of outcomes (revision) may not provide all the necessary information needed to determine the success rate of total knee replacements in this age group. This means the current reported outcomes of total knee replacements in younger patients may be too optimistic.