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
Very interesting results from this reference.
(osteophyte formation, joint space changes (or lack there of) and cartilage formation).
I know in my patient population, the groups with sign structural changes (knee valgus/varus) or patellofemoral issues are my biggest nonresponders.
It is nice to know that the literature supports physical activity as "not" being a detriment.
Hi Tom: The results are kind of reassuring but I think the debate is far from over. We need a lot more high quality research (hopefully, clinicians/researchers in sports medicine/sports sciences will lead the way). There is some interesting animal work being done at Ohio State that supports an idea that when the loading occurs during the disease progression may be an important risk factor. I would keep an eye on this because if this is true then the implications to rehab could be dramatic.
This topic is very interesting and it is debatable issue. Even if we have perfect lower extremity biomechanics during physical activity, eventually we might experience the osteoarthritis because of repetitive compression on the knee joint. However, physical activity itself will have various positive-effective to the body such as hormone regulation, reduce body fat..etc. . I think that physical activity with structural changes or neuromuscular dysfunction would be the factor to increase occurring early onset of OA.
Eunwook: Thanks for the comment. I think we could be looking at a bell shaped relationship. Joints don't respond well to being immobilized and nonweight-bearing, based on this study physical activity may be protective of joint degeneration, and then when the joint is exposed to macro-loads (e.g., ACL tear) or very high repetition (particularly with inadequate rest) then it could be degenerative. A good example is that several studies have suggested that running is beneficial to the joint BUT elite-level marathoners (olympic competitors) may be at an increased risk. This might be b/c they start running at a younger age, run more miles than most people, or push through injuries.
Overall, it's probably wise for us to advocate that patients should pursue physical activity. It has many health benefits, may help the joints, and in rare cases may increase the risk slightly.
This was a recent abstract presented at the American College of Rheumatology that looked at sports and knee OA: https://www.rheumatology.org/about/newsroom/2011/2011_ASM_03_athletes_knees.asp