Studies also confirm a statistically significant link between obesity and incidence of osteoarthritis. Compared with patients who have a normal BMI, the need for a total knee arthroplasty (knee replacement) is estimated to be 8.5 times higher in patients with a BMI greater than 30, 18.7 times higher in patients with a BMI greater than 35, and 32.7 times higher in patients with a BMI of 40 or greater.
Source: Journal of the American Academy of Orthopedic Surgeons, November 2014