Purpose of review: We discuss recent published epidemiologic data regarding risk factors for incident and progressive knee osteoarthritis and related knee pain to identify targets for primary and secondary prevention. We also discuss recently identified methodologic challenges to the study of knee osteoarthritis, particularly osteoarthritis progression.
Recent findings: Recent epidemiologic studies and systematic reviews of knee osteoarthritis have confirmed that being overweight and obese, and knee injuries increase the risk for incident knee osteoarthritis. Biomechanical risk factors such as leg-length inequalities and malalignment require further study. Obesity also appears to play a role in accelerating osteoarthritis worsening. However, with the exception of malalignment, no risk factors for knee osteoarthritis progression have been identified. Novel approaches to the study of knee pain have demonstrated a strong association between structural abnormalities and knee pain, contrary to the 'so-called' structure-symptom discordance, as well as between fluctuations of knee pain with changes in specific structural lesions. A number of methodologic issues, including conditioning on an intermediate stage of disease and depletion of susceptibles may explain, in part, the difficulty in identifying risk factors for knee osteoarthritis.
Summary: There is strong epidemiologic evidence that being overweight or obese and knee injury are associated with increased risk of developing knee osteoarthritis. Further study is required to confirm associations of leg-length inequality and malalignment with incident knee osteoarthritis. Few new risk factors for progression of knee osteoarthritis have been identified in the past few years. Without such knowledge, secondary prevention of osteoarthritis remains challenging.