Arthritis means pain in the joints, but most people don’t realize that it’s an umbrella term for more than 100 different conditions. As an orthopedic surgeon the type I see most often is osteoarthritis, and for good reason: It’s the most common type of arthritis, by far.
Taking this one step further, the knee is the most common site of osteoarthritis. It’s because the knee is a weight-bearing joint, subject to the stresses of gravity. Your weight will have a lot to do with your risk of developing knee osteoarthritis. If you’re overweight, your risk can jump by up to five times that of a healthy-weight person. On the upside, however, for every 10 pounds you lose, you could cut your risk by up to 50 percent.
What Is Osteoarthritis?
To understand osteoarthritis, it’s important to understand the structure of joints. Each joint is a meeting place of two or more bones. In the knee’s case, there are three: the femur, or thigh bone; the tibia, or shinbone; and the patella, or kneecap. Along with bones, there are usually ligaments holding bones together, tendons that attach muscles to bones, and cartilage.
Osteoarthritis is a problem with a particular type of cartilage called articular cartilage. Articular cartilage wraps the ends of bones in a joint, enabling them to glide together and preventing painful bone-on-bone contact. Osteoarthritis is the breakdown of articular cartilage. If osteoarthritis progresses far enough, there will be no articular cartilage left and the bones will rub together, causing pain and structures known as bone spurs.
BMI and Healthy Weight
Osteoarthritis is incurable, but it’s certainly not untreatable. There are a variety of surgical and nonsurgical treatment options that can relieve symptoms and stop the condition from getting worse.
One of the best ways to improve your quality of life when you have knee osteoarthritis is to maintain a healthy bodyweight. Body mass index (BMI), while not perfect, is usually a pretty good indicator of a healthy weight. To figure out your BMI, you divide your weight in kilograms by your height in meters, squared—no need to do it by hand; you can use a calculator from the Centers for Disease Control and Prevention (CDC) or other organizations.
A healthy BMI is generally considered to be between 18.5 and 24.9 for adults, according to the CDC. Over 30 is obese, while between 25 and 25.9 is overweight. As I mentioned, it’s not a totally accurate measurement for health, but it’s pretty good, especially when considering the effect weight has on knee osteoarthritis. An athlete who is heavily muscled may have a low risk of health problems with a high BMI, but if he or she is heavy, that’s still extra stress and wear-and-tear on the knee.
Knee Osteoarthritis and Weight Loss
Keeping the weight off means less pressure on your knees. A 2013 study estimated that, with every step you take, you’re putting force on your knee equal to 2.5 times (or more) your bodyweight. It’s even higher when running. So, it stands to reason that lower weight means less force.
A June 2018 study in Arthritis Care and Research looked at data from 240 overweight or obese people with knee osteoarthritis. The results suggested that the people who lost the most weight—20 percent or more of their starting body weight—had the lower levels of inflammation, reported less pain and could walk farther during a six-minute walking test than people who lost 5 percent or less. Even compared to people who lost between 10 and 19.9 percent of their weight, those who lost 20 percent or more reported significant differences.
Losing Weight With Knee Osteoarthritis
If you are overweight and have knee osteoarthritis, you might be thinking it’s difficult or impossible to lose the weight. You’re in pain and you’re afraid of damaging your knee further with exercise. But, losing weight is absolutely possible.
To lose weight, diet is key. Weight loss is a math problem: If the calories you burn are less than the calories you consume, you’ll lose weight. It’s as simple as that—though that doesn’t mean it’s easy.
Look for foods that have few calories but still fill you up. Aim for a mix of fruits, vegetables, lean meats and healthy fats, if not at every meal then at least every day. Avoid processed foods and refined sugars—these will cause your blood sugar to spike and then crash, leaving you sluggish and just as hungry as you were before.
For exercise, focus on low-impact activity. Remember, while exercise is beneficial for more than just your waistline, you don’t strictly need it to lose weight. It’s all about calories in versus calories out. That said, exercise can still be helpful in shedding the pounds.
Low-impact exercises are those that minimize the force on your knees. Low-impact cardiovascular activities include:
- Elliptical machines
- Stair climbers
You should also consider resistance training, both to help you lose weight and to help your knee osteoarthritis. Resistance training can be done with your own bodyweight, machines or free weights. Building muscle means your body needs more calories to maintain its weight, making it easier to lose weight by eating less. And, when it comes to knee osteoarthritis, resistance training can help you move better with your knee and preserve or restore physical function, according to a 2013 study published in the journal PM&R.
If you are living with knee osteoarthritis, request an appointment with me. I can help you develop a treatment plan that works for you and your circumstances, as well as help ensure your weight loss efforts are safe and successful.