A new study corroborates a favourable effect of weight loss on development and progression of knee – but not hip – osteoarthritis.

Obesity is a risk factor for developing osteoarthritis (OA) in weight-bearing joints. In this study from the longitudinal US Osteoarthritis Initiative, researchers used data from 2800 participants (age range, 45 to 79 years) to take a closer look at the effects of weight gain and weight loss on development and progression of knee and hip OA.

During a four-year period, about 11% of participants had radiographic evidence of progressive osteoarthritic changes in the knee. Compared with people who had no weight change, those with more than 5% weight gain were more likely to have radiographic progression, and those with more than 5% weight loss were less likely (odds ratios, 1.29 and 0.69, respectively). Among those with weight gain who had progressive changes, medial joint space narrowing was the dominant finding. Patterns of progression or resolution of knee pain paralleled the radiographic changes. In contrast, weight gain or weight loss were not associated with development or progression of hip pain or radiographic changes at the hip. 

Comment: These results reinforce the importance of addressing weight in patients with existing knee OA. Moreover, when we counsel middle-aged or older overweight patients on the general health benefits of weight reduction, we can mention that some protection against developing knee OA is a potential added benefit. Unfortunately, this study and others show that interventions such as weight reduction and physical therapy are less likely to improve symptoms in patients with hip OA.

Allan S. Brett, MD, Clinical Professor of Medicine, University of Colorado School of Medicine, Aurora, USA.

Joseph GB, et al. Effects of weight change on knee and hip radiographic measurements and pain over four years: data from the Osteoarthritis Initiative. Arthritis Care Res (Hoboken) 2023; 75: 860-868.

This summary is taken from the following Journal Watch titles: General Medicine, Ambulatory Medicine.