Blog Post 7 (Week 9) - Study shows that knee replacement is a good option even for severely obese patients

Knee replacement

This week, I will be assessing the use or misuse of science in an article published on U.S. News & World Report, titled "Knee Replacement a Good Option, Even for Severely Obese, Study" by Robert Preidt.

Summary of Article:

This article reports on the findings from a recent study on knee osteoarthritis claiming that "total knee replacement is a cost-effective treatment", even for extremely obese people with the condition. Due to increased risks of "poor wound healing, infection, and implant failure" in extremely obese patients, doctors are more hesitant to perform total knee replacement for them. However, the new study found that, after running a computer simulation to assess the costs and benefits of the surgery for extremely obese people, they found that, in both younger patients and patients older than 65 years, "total knee replacement is a cost-effective treatment." Generally, most extremely obese patients with knee osteoarthritis considering total knee replacement are younger patients, which provides some more reassurance for the value of the surgery for these people. The author of the study, Elena Losina, has said that extremely obese people "experience substantial pain reduction from [total knee replacement], leading to meaningful improvements in quality-adjusted life expectancy." For these reasons, she said that surgeons should try to "accommodate these patients and provide accurate information about what to expect post-surgery" instead of asking whether or not to do surgery.

Science in the Article:

This article reports on the findings from a study that was published in the Annals of Internal Medicine Journal on March 23rd, 2021, titled "The Value of Total Knee Replacement in Patients With Knee Osteoarthritis and a Body Mass Index of 40 kg/m² or Greater" by Chen et al (the principal investigator is Dr. Elena Losina, whose statements were provided in the news article). The study was designed to "assess long-term clinical benefits, costs and cost-effectiveness of TKR [total knee replacement] in patients with a BMI of 40 kg/m² or greater." They found that quality of life was indeed increased for extremely obese patients after TKR, with a greater increase observed for patients younger than 65 (increased by 0.71 year) as opposed to older (increased by 0.39 year). They also concluded that TKR "offers good value" for these patients, "including those with multiple comorbidities." Although the news article focused mostly on obesity as the main factor and not additional comorbidities, overall it still represented the results of this study accurately.

Another study involving assessing the risk of total knee replacement surgery for obese patients with knee osteoarthritis is titled "Obesity and the Relative Risk of Knee Replacement Surgery in Patients With Knee Osteoarthritis: A Prospective Cohort Study" by Leyland et al. This study sought to answer a different question, which is the relative need for knee replacement surgery for overweight and obese patients as compared to normal patients. Interestingly, they found that "Overweight and obese patients are at >40% and 100% increased risk of knee replacement surgery, respectively, compared to patients with normal weight" and the association "is even stronger in younger patients." The news article does mention that obesity can actually increase the patient's likelihood of needing knee replacement surgery, which is an interesting dynamic, especially as the new study suggests that these very obese patients are more likely to be turned away from getting the surgery.

Finally, a study titled "Knee replacement in morbidly obese women" by Pritchett and Bortel reported on the results of sixty-six total knee replacements in 50 morbidly obese women with osteoarthritis. They found that 86% of nonobese patients had excellent or good results, while 57% of morbidly obese patients had excellent or good results. The authors concluded that "total knee replacement is safe and reasonably effective in the morbidly obese." This study reinforces the findings from the recent study that is reported on by the news article, in that knee replacement surgery for extremely obese patients with knee osteoarthritis is effective and a "good option." Therefore, the article reflected the risk assessment of knee replacement in extremely obese patients fairly accurately.

Assessment: Was Science Misused?

Based on the findings reported in three related scientific articles, I think that the science represented in this U.S. News & World Report represented the science accurately. The one thing I wish the article expanded upon more is the relative medical risks for obese patients with knee osteoarthritis that end up NOT getting knee replacement surgery. In the second scientific article, the scientists reported that obese patients are actually at greater risk of needing knee replacement surgery in the first place compared to normal patients, despite the risks associated with the surgery being worse for obese patients than normal patients. This adds another interesting dynamic to the conversation regarding how best to determine whether or not to allow obese patients to get the surgery. While the news article did a good job of accurately summarizing the findings from the new study, I think that the most important takeaway (that this article adds as a final thought in the words of Losina) is that "this is a discussion that should take place between individual patients and physicians, discussing the risks, complications, and benefits, as well as considerations of operating room accommodations that would optimize the work of orthopedic surgeons performing [total knee replacements] in these patients." Regardless of the doctor's assessment, it is important to allow the patient to actively participate by informing them accurately of all the risks and benefits involved in the surgery, so they can decide for themselves what they want. So not only does this news article do a good job of representing the science accurately, but it also encourages doctors to accurately represent the risks and benefits of the surgery for the patients, to help them make the decision to undergo the surgery for themselves.

Thanks for reading!