I often hear from patients that when they lose weight, their joints feel better. While this makes common sense, does losing weight also get rid of structural arthritis? Meaning, do the bone lesions and cartilage issues also resolve? A new study set out to answer that important question.
Knee Arthritis and Obesity
Knee arthritis involves not just the cartilage but also the bone that helps form the joint. Cartilage provides both a cushion and a smooth, slick surface for the bones. The cartilage cushion lives between these bones and absorbs shock, and its slick surface also allows the bones to smoothly glide as the knee bends and moves. The bone also provides shock absorption. How? Most people think the bone is like hard cement, when in fact, it’s more like hard plastic.
If you’d like a more in-depth review of how the knee structures look, especially if you might be wondering how to read your MRI, watch my video below:
Cartilage can wear down for a variety of reasons: normal wear and tear, disease, or injury. As the cartilage wears down, this leads to arthritis. In the worst cases, cartilage can wear out completely, creating very severe bone-on-bone arthritis. Bone spurs also form to attempt to protect an arthritic joint from further deterioration. The bone can also develop lesions that have tiny microfractures in the structural supports that live inside. These can be seen on MRI and are called bone marrow lesions (BML) or bone marrow edema (BME).
So does weight loss help knee pain and arthritis? A new study suggests you can’t change the structure of an arthritic knee by losing weight, but other studies suggest you can improve pain and function. Let’s take a look.
Weight Loss May Not Improve Structure in Arthritic Knees
The new study investigated whether weight loss in obese patients actually improved the structure of arthritic knees. Knees were assessed in 75 severely obese patients both before bariatric surgery or a diet program and again one year later. MRIs were studied at both time points for cartilage damage, bone marrow lesions, and more, and cartilage thickness was measured.
The results? No changes were found in lesions, cartilage damage, and other indicators regardless of how much weight was lost. Cartilage thickness also was not shown to change on MRI. So this study doesn’t support that losing weight will help your images look better. In other words, according to this study, losing weight won’t improve the structure of your knee or knee arthritis.
Weight loss may not improve the structure of arthritic knees (meaning it may not reverse the structural damage that’s already been done), but studies do show many other knee benefits after weight loss.
Does Weight Loss Help Knee Pain by Improving Other Knee Arthritis Issues?
There are many benefits to losing weight and exercising, even if you have knee arthritis. One study found that even in patients with severe arthritic knee pain, exercise decreased the pain. In fact, the average pain level of participants was 7 out of 10, and their pain dropped by almost 40%. The same study also found that not only did knee function improve with exercise but so did the participants’ muscle strength. Another study takes this further, finding that improvements in muscle cocontractions brought on by regular exercise improves stability and could be the reason exercise decreases knee arthritis pain.
Is there one type of exercise better than another for knee arthritis? A study a few years ago found that the best exercise to relieve knee arthritis pain was using weights for nonweight-bearing exercises, such as knee extensions. Nonweight-bearing exercises were better for knee arthritis than both weight-bearing and aerobic exercise.
Another big benefit to exercising to improve knee arthritis pain is that a recent study found that exercise was more effective than dangerous nonsteroidal anti-inflammatory drugs (NSAIDs), like Motrin, Celebrex, Aleve, and so on, at relieving pain, easing symptoms, improving function, and so on. And unlike NSAIDs, which come with many horrible side effects, exercise won’t only improve your knee symptoms, but exercise also comes with many other well-known benefits as well.
The upshot? After all is said and done, does weight loss help knee pain and arthritis? Losing weight may not make your MRI look better, but you may feel better. Given that most patients I know have opted for big surgery primarily because their knee hurts, a knee that feels better should be enough to avoid the knife. So lose weight if you have knee arthritis; while your radiologist may not be impressed, your physical therapist will thank you.