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  • Study Finds Association Between Knee Replacement and Weight Gain

    A new study finds that knee replacement surgery may raise a person's risk of gaining weight, says a Reuters News  article based on a study published in Arthritis Care & Research.   

    For this study, lead investigator Daniel Riddle, PT, PhD, FAPTA, and his group used a patient registry from the Mayo Clinic in Rochester, Minnesota, which collected information on 917 knee replacement patients before and after their procedures.

    The researchers found that 5 years after surgery, 30% of patients had gained at least 5% of their weight at the time of the surgery.

    In contrast, fewer than 20% of those in a comparison group of similar people who had not had surgery gained equivalent amounts of weight in the same period.

    Riddle's team said that this degree of weight gain can lead to "meaningful effects on cardiovascular and diabetes-related risk as well as pain and function."

    One possible explanation for the counter-intuitive results, experts said, is that if people have spent years adapting to knee pain by taking it easy, they don't automatically change their habits when the pain is reduced, reports Reuters.

    "After knee replacement we get them stronger and moving better, but they don't seem to take advantage of the functional gains," said Joseph Zeni, PT, PhD, a physical therapy professor at the University of Delaware, who was not part of the study. "I think that has to do with the fact that we don't address the behavioral modifications that have happened during the course of arthritis before the surgery."

    Part of the explanation for the weight gain could be the age at which patients get surgery. People in their 50s and 60s tend to gain weight, anyway. Still, in light of the lower rates of weight gain in the comparison group, which was also middle aged and older, Riddle said something else may also be at work.

    In fact, the team found that patients who had lost weight before their surgery were slightly more likely to gain weight afterwards—perhaps because when people lose weight in anticipation of an event, such as surgery, they are more likely to put it back on after they're achieved the goal, says the article.


    • Stuff like this gives me a headache. The control group did not have knee replacement. Did the control group have diagnosed osteoarthritis of either knee? Were they candidates for knee replacement surgery? I've had patients who went on to do really well and remain active. I've also had patients I ran into years later, and didn't recognize them. If a patient is a good candidate for knee replacement, they're going to gain alot more weight without it than they will with it.

      Posted by Leon Richard on 12/12/2012 1:12 AM

    • Leon, gives me a headache too.... if a cohort in a study does not match my cohort then all of it becomes nothing more than useful information not reason to change anything. My wife had 2 bad knees, one replaced and the other not, she never slowed down and is at same weight she was 5 years ago with one bad knee still barking at her every single day... if people want to act and function in a disabled manner, they will, despite what any health care professional does for them...

      Posted by Paul KLeponis, BSEd, PT, DPT on 12/17/2012 1:12 PM

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