What is the effect of physical activity on the knee joint? A systematic review.

Urquhart DM, Tobing JF, Hanna FS, Berry P, Wluka AE, Ding C, Cicuttini FM.
Med Sci Sports Exerc. 2011 Mar;43(3):432-42.
How does physical activity influence the development of osteoarthritis? This is a question that continues to linger in medical fields associated with physical activity. On the one hand, physical activity increases the amount of loading our weight-bearing joints experience, but on the other hand our bodies are designed to be active and adapt to repetitive loading (when given adequate recovery time). Urquhart et al attempted to address this question by performing a systematic review examining the relationships between physical activity and specific joint structures of the knee (specifically the tibiofemoral joint). The systematic review included 28 articles with a large range of physical activities. The authors concluded that knee structures are affected differently by physical activity and that there is strong evidence that:  1) there is a positive relationship between osteophytes and physical activity; 2) there is no relationship between joint space narrowing and physical activity, and 3) there is strong evidence that there is an inverse relationship between cartilage defects and physical activity. There was also weak evidence that there is a positive relationship between cartilage volume and physical activity.,
This systematic review is not the final word on this issue. There are plenty of other additional questions about specific types of activities and groups of people that were not addressed in this review. One of the greatest limitations to exploring this question in more detail was noted by Lievense et al (2003) in a systematic review of hip osteoarthritis and sports: “The quality of studies reporting on this relationship…is disappointingly low.” This will be a debate that continues for years and as sports medicine clinicians we should try to keep up-to-date on the latest literature and encourage more research into this question. I am surprised at how many clinicians (not regularly working with physically-active individuals) assume that physically activity individuals will have osteoarthritis. Hopefully, this study will cause them to pause and think that perhaps the answer is not as straight forward as they assume. We need to educate our fellow clinicians and our patients about the relationship between physical activity, injury, and osteoarthritis; as well as the limitations to our knowledge. There’s also a desperate need for the sports medicine community to get more involved in osteoarthritis research.

Written by: Jeffrey Driban
Reviewed by: Joseph Zeni