As an orthopaedic surgeon who performs a significant number of total knee replacements, I have observed more frequent complications in those patients who live with obesity. Several studies have also spotlighted this trend. A recent report out of Europe pooled together data from multiple total knee replacement studies and determined that obese patients are nearly twice as likely to have a local infection after a total knee replacement, more than twice as likely to have a deep infection, and slightly more likely to require a surgical revision than those who are not obese. Obese for the study was defined as those patients with a Body Mass Index (BMI) greater 30. An example of this BMI would be a 5’8” male who weighs 200lbs, but many obese patients have BMIs greater than 35, 40, or even 50.
We have known for years that obese patients can be very happy with their total knee replacement outcome and in some cases, even more satisfied than their non-obese counterparts. Unfortunately, patients with obesity do run a higher risk for infection and they tend to have complications associated with obesity, such as diabetes and coronary artery disease. As physicians, we owe it to our patients to try to optimize their surgical results. As such, I strongly encourage weight loss for all of my patients, but particularly those contemplating a weight-bearing joint replacement. Patients who lose weight and build muscle prior to joint replacement can expect a smoother recovery following surgery.
Often, those with bad knee arthritis have will have difficulty with any exercise to lose weight. Many patients will claim they will lose weight after the knee gets replaced but research shows otherwise. (If anything, these patients tend to gain more weight with the new joint in place.) If water therapy is possible, it too may serve as an alternative exercise regimen. When exercise is too painful or the patient seems otherwise unwilling to exercise, we attempt to at least modify diet. Patients are not encouraged to rapidly diet, but we will set modest weight loss goals to be attained over time.
No one is claiming that weight loss is easy, but I believe that if more people were educated about the difference a little weight loss makes to your joints, they would better understand why it is so strongly encouraged by orthopaedic surgeons. For example, did you know that for each pound of weight you lose, 6-8 lbs of force will be taken off of your knees? A ten pound weight loss over 6 months means you’ve removed 60-80 pounds of force from your knees! Until we get it under control, America’s obesity epidemic is going to continue to strain the knees of Americans and the success rate of the valuable procedure of total knee replacement.
Dr. David T Schroder is a board-certified orthopaedic surgeon, fellowship trained in total joint replacement, with The San Antonio Orthopaedic Group. He treats patients aged 11 years and up for most orthopaedic conditions, with the exception of spinal surgery. He has a special interest in total knee replacement. To schedule an appointment with Dr. Schroder, please call 210.281.9595.
To see the study that Dr. Schroder is referencing, click here.