Joint Replacement and Weight

It is important to maximize outcomes following hip or knee replacement by optimizing your health preoperatively. While many factors affect the outcome of the surgery, a common predictor of surgical outcome is the body mass index or BMI. While somewhat controversial, many hospitals will not operate on patients with a certain BMI.

Weighing a patient before total hip or total knee replacement

Standard Reasons for Joint Replacement

The most common reason for joint replacement surgery is osteoarthritis. Osteoarthritis is a condition that causes stiff, painful joints, generally caused by overuse or previous injuries. Commonly replaced joints are knees, hips, and shoulders.

Obesity is a particularly common reason for joint replacement. Excess weight places excess stress on joints. This causes joint damage and pain. Unfortunately, this is a vicious cycle. More pain makes people less likely to exercise, which worsens obesity, which worsens pain. Joint replacement can help obese people with daily movement, but obesity itself may affect the outcomes of joint replacement surgery.

BMI and Joint Replacement Outcomes

Many hospitals or surgeons are reluctant to do a joint replacement on patients with a BMI above a certain limit. Often, this limit is a BMI over 40. Many centers base these limits on multiple research studies, finding worse outcomes for obese patients.

For example, a review of nine studies looked at outcomes of knee replacements in obese vs. non-obese patients. Overall, studies find that obese patients who receive a knee replacement are more likely to need revision surgery in a 5-year period. Specifically, 7% of the obese patients need a revision compared to 2% of non-obese patients. Additionally, they found that obese patients were more at risk for complication infection or implant loosening.

Body Mass Index (BMI)

BMI is a person’s weight in kilograms divided by their height in meters squared, or (kg)/(m2). This is a helpful metric because it allows health professionals to consider height when contemplating weight. Standardizing weight in this way is useful in research. For example, researchers are able to use BMI to determine how weight affects certain treatments. This is especially true when measuring surgical outcomes.

Obesity is defined by the World Health Organization as excessive fat accumulation that presents a risk to health, normally defined as a BMI of 30 or greater. Assessments by a large number of research studies show that a BMI of 30 or greater is associated with a number of chronic health issues, such as cancer, heart disease, and diabetes.

Limitations of BMI Limits

Other studies find that enforcing a BMI limit may be unfair to patients. For example, one study argued that the major complication rate for obese patients undergoing hip or knee replacement was only slightly higher than the average rate (6.74% vs. 5%). In other words, if all of those obese patients had been denied surgery, 14 patients would have been denied a complication-free surgery for every one person that had a complication. They argued that these 14 patients deserved a chance for a complication-free surgery. Another study argued that overall, obese and non-obese patients had similar absolute improvement scores.

Measuring BMI before hip or knee replacement

Weight Loss Resources in Hawaii

Losing weight is difficult for anybody, but it may be more difficult in the obese patient who has painful joints. Thankfully, there are many resources to help people lose weight. Choosing the right resource just depends on what each patient is looking for.

For example, some people prefer to try to lose weight by themselves. Calorie counting apps (MyFitnessPal), meal programs (Jenny Craig), or cognitive-behavioral approaches (Noom) are options. Following a mindset and nutritional approach like Intuitive Eating, touted by many nutritionists, is an alternative to dieting.

Others may want a more team or partner-based approach. Nutritionists, sometimes covered by insurance, can help people understand changes they can make to improve their health and weight. Team-learning programs, like Weight Watchers, help people understand nutrition while also learning from their peers.

Kūlana Hawai’i, a weight management program geared towards rural residents on Oahu and Molokai, combines nutrition with peer-learning. Kūlana Hawai’i serves mostly underserved residents. They understand that there are many more factors of weight than just diet and exercise. The team includes a psychologist, a nutritionist, and a fitness instructor. The team works with participants to develop a goal and treatment plan. Additionally, they offer exercise and fitness classes, stress management techniques, and group sessions. They believe their approach works; of their participants, over 75% lost weight, increased their exercise, and expanded their health knowledge base. They hope that these changes are sustainable and empower patients to continue their health journey after they complete the program.

Queen’s Medical Center also offers an excellent resource with the Comprehensive Weight Management program. We often refer our patients for their evaluation and consideration of non-operative and operative treatments for obesity.

In partnership with Prescribe FIT, Dr. Morton is offering a new lifestyle health program designed specifically for orthopedic patients to decrease weight, reduce pain, improve mobility, and better prepare for and recover from surgery.

Prescribe FIT helps patients improve their health through simple changes to nutrition, physical activity, and lifestyle. It’s also covered by insurance through Medicare, Medicaid, and most commercial insurance carriers. Our team will review your benefits eligibility and financial responsibility for the program prior to enrollment.

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Living with painful joints limits patients’ everyday lives. Some hospitals limit who can get a joint replacement surgery if they are over a certain weight. While some critics argue that this practice is unfair, some hospitals argue that they just want the best outcomes for patients. Weight loss is difficult, but there are many resources depending on what approach is best for each individual. Contact us today to learn more about your options for knee or hip replacement.