This week's article is a systematic review of the literature investigating the impact running has on knee osteoarthritis. There were 17 studies which met inclusion criteria, with over 14,141 participants included. The presence of knee pain ranged from 10.2-35.4% in runners and 13.4%-58.8% in nonrunners, but the paper talks little about this outside of saying there is lower presence of knee pain in runners. It is possible that some of the nonrunners used to run but stopped due to knee pain, or were told to stop from radiographic imaging. There was one study which found a significantly higher prevalence of patellofemoral joint space narrowing and more osteophyte prevalence in the patellofemoral and tibiofemoral joints in runners than nonrunners, but two studies comparing radiographic knee osteoarthritis between runners and nonrunners found no difference between groups. There was no significant differences in cartilage thickness at various locations in the knee between runners and nonrunners, while total knee replacements were performed on 2.6-3.9% of runners and 4.3-4.6% of nonrunners. Overall, the evidence appears to show that there is no difference in many characteristics of osteoarthritis (pain, radiographs, cartilage thickness, and prevalence of total knee replacements) between runners and nonrunners. However, there are a few limitations to this article. We personally did not feel very impressed with the robustness nor the interpretation of the data. This is a subject that has to have a lot of nuance and grey areas, but this paper felt very black and white. A lot of the decisions around knee replacement, and even whether to keep running in the presence of joint space narrowing, are largely impacted by the words and beliefs of the provider. Additionally, there is no discussion of the impact of running volume on these factors associated with osteoarthritis. It is theorized recreational running volumes could be protective against arthritis, or at least not inherently damaging the knee joint. However, those who run at large volumes could have higher incidences of knee arthritis in line with the "wear and tear" explanation for the cause of arthritis. There is still a lot more research to be done in this area!

The abstract can be found here: https://pubmed.ncbi.nlm.nih.gov/36875337/

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