The Arthritis NewsletterSummer 2018
Knee Swelling, Obesity and Early Signs of OsteoarthritisBy Trish Silvester-Lee and Sheila Kerr
Osteoarthritis (OA) is the most common form of arthritis, affecting 1 in 8 Canadians. It is commonly thought of as pain and inflammation resulting from “wear-and-tear” of the joints, but new research shows that inflammation is often a contributing factor to joint swelling and pain. One important risk factor for the inflammatory part of the disease is obesity.
Dr. Jolanda Cibere, Arthritis Research Canada (ARC) Senior Scientist and Rheumatologist, studied the link between inflammation, obesity, and knee osteoarthritis. She followed a group of people aged 40-79 years old who had pain, aching or discomfort in and around the knee. They were randomly selected from the general population to participate in a study called the Vancouver Longitudinal Study of Early Knee Osteoarthritis (VALSEKO). The aim of the study was to learn about early-stage OA, in hopes of preventing joint damage before it occurs.
Dr. Cibere’s research found that of those complaining of knee pain,
- 38% had OA that could be seen on an x-ray
- 49% had signs of pre-OA determined by an MRI scan only (their x-ray was normal)
- 13% didn’t have OA (both their x-ray and MRI were normal)
Interestingly, the majority of study participants had knee swelling. Knee swelling occurs as a result of inflammation of the lining around the joint. MRI scans detected that 55% of participants had low-grade knee swelling, while 14% had moderate-severe swelling. Tests for knee swelling were done at the beginning of the study and again at 3 and 7 years.
One of the important outcomes of the study was the link between obesity and knee inflammation. Regardless of whether or not participants had swelling in the knee at the beginning of the study, those who were considered obese had a 3x increased risk of knee swelling over 3 years, compared to those who were not overweight. This risk develops due to extra weight bearing on the joint and active inflammation. This highlights the importance of healthy weight management for arthritis prevention and symptom control.
This study brings up the point that while X-rays are typically used to diagnose and assess knee OA, they often miss early warning signs of joint inflammation. MRIs are able to detect early inflammation – but, they are currently only used for research purposes, not for clinical diagnosis.
Maintaining a healthy weight and participating in exercise are two key tools we can use to decrease risk. For great weight management tips and tricks from our own Arthritis Patient Advisory Board (APAB) members, see the related article in this issue’s newsletter.
Body Mass Index (BMI), a measure of body mass based on height and weight, is a tool to screen for obesity. Search for a ‘BMI calculator’ on the internet to find out your BMI.
BMI classifications list:
- BMI <25 is normal
- BMI 25-29.9 is overweight
- BMI >30 is obese