The following is a summary of the “Association between weight gain and knee osteoarthritis: a systematic review,” published in the March 2023 issue of Osteoarthritis and Cartilage by Solanki, et al.

Despite the fact that humans often gain weight as they age, which may alter the symptoms and course of knee osteoarthritis (KOA), losing weight is still suggested for managing KOA. The purpose of this study was to systematically analyze and synthesize data on the association between weight gain and KOA, as measured by clinical characteristics, structural progression, and total knee replacement (TKR). They searched MEDLINE and EMBASE for randomized controlled trials and cohort studies of people with (or at risk for) KOA that looked at the association between weight gain and KOA clinical characteristics (pain, function, quality of life), structural progression, and TKR.

The ROBINS-I instrument was used to determine the degree of bias. Outcomes were used to categorize the results, and meta-analyses were done when necessary. There were 23 total studies included. Around 4 of 7 studies found that weight gain significantly worsened pain, 2 studies found that it worsened stiffness, and 5 of 6 found that it worsened function. The studies looking at the quality of life and clinical and radiographic Outcomes also found negative effects on weight gain. There was a negative correlation between weight gain and injury to many joints, including cartilage (6 of 9 studies), bone marrow lesions (1 of 4 studies), meniscal damage (1 of 3 studies), and effusion/synovitis (1 of 1 study). 

Around 3 out of 6 studies found a correlation between weight gain and an increased risk of TKR; a meta-analysis of the 2 studies with sufficient data showed a statistically significant increase in TKR per kilogram of weight gain for women (HR 1.34; 95% CI 1.18-1.51) and a similar trend for men (HR 1.25; 95% CI 1.16-1.34). The clinical and structural rates of KOA and TKR rise in tandem with adult weight gain. KOA patients would benefit from thinking about ways to avoid putting on weight.