Exercise and Cartilage Health in Humans and What to Tell Patients

The first review looked at cartilage on MRI in people at risk, such as those with a previous knee injury or high BMI, and in people with knee osteoarthritis. Interventions ranged from aquatic exercise to jumping. Exercise did not change cartilage volume, thickness or defects. For composition, one aquatic study showed aggrecan loss along with a collagen gain, three showed no effect and three showed benefit, which suggests aggrecan and collagen can respond to exercise. The second review used biomarkers from blood, urine and synovial fluid, including IL-6, CRP and TNF-alpha. Most studies of aerobic and strengthening exercise showed no change or a decrease in inflammation and matrix turnover. Taken together, exercise therapy appears to load cartilage moderately and does not seem harmful, though no intervention consistently improved cartilage, so patients should not be promised that. Alessio's three steps: ask whether the patient is concerned that exercise may harm the knee, explain its safety with the sponge analogy, and address misconceptions while stressing that a gradual, tailored program is safe and helps symptoms and general health.