Significance and definition of early knee osteoarthritis

Takashi Kanamoto, Tatsuo Mae, Teruki Yokoyama, Hiroyuki Tanaka, Kosuke Ebina, Ken Nakata


Osteoarthritis (OA) is a degenerative joint disease that causes joint dysfunction due to pain and restricted range of motion and it causes lowering of physical activity and the quality of life and results in a significant effect on the global burden of disease. Early diagnosis of OA in the knee joint is critical for effective treatment before facing severe irreversible pathology, and to develop new OA treatment techniques. Discussion on defining early OA has become more globally active. In this review, two proposals of the definition of early knee osteoarthritis, the Italian Rheumatology Association International and the First International Early OA Workshop proposed are introduced. These definitions of early OA have been proposed with a combination of “symptoms” of joint pain, “signs” such as joint stiffness, tenderness, or risk factors, and diagnostic imaging such as radiographs. Consensus on a more detailed classification and validation of the proposed definition of early OA are necessary to develop new treatment methods to suppress or prevent symptoms at an early stage before any progressive and irreversible change. Diagnostic imaging techniques such as MRI and ultrasound are superior compared to X-ray for visualization of soft tissues of joints and quantification of physical activity will become a key for the evaluation and development of new treatment strategies for early stages of osteoarthritis in the near future due to the fact that the structural and qualitative abnormalities of joints directly affect physical activity, and improvement of that will be the primary outcome of treatment for osteoarthritis in society.