Mend Physical Therapy Blog and Injury Information

The Greatest Weakness Of The Wear And Tear Hypothesis For Joint Arthritis

February 11, 2021


Authors estimate 1 in 10 Americans over age 60 report symptomatic, not to be confused with those who are pain free but have arthritis on x ray, knee osteoarthritis. Knee arthritis is one of the leading causes of disability due to its’ impact on functional activities such as getting out of chair, walking, standing, and stair climbing. Physical Therapy, including manual therapy and exercise, remains a first line treatment for this condition with researchers showing these treatments can delay or prevent the need for a total knee replacement.

As with many healthcare conditions, the outcomes for patients with knee osteoarthritis are strongly influenced by its’ initial management including the education of the patient. An outdated hypothesis behind osteoarthritis includes the description of “wear and tear”. In short, too much activity has worn down the cartilage surfaces at the joints causing arthritis. This hypothesis has been disproven in the recent research with active individuals showing less knee arthritis than their sedentary peers. Specifically, exercise has a protective, nourishing effect on our joints cartilage. This leads to another weakness in the wear and tear hypothesis.

The CDC reports a progressive increase in the percentage of sedentary adults in America, most pronounced in the South and Midwest. If wear and tear is a significant player in knee arthritis this progressive decrease in activity should be associated with a decreased incidence of symptomatic knee arthritis. Instead the incidence of knee arthritis has doubled since the 1950s at a greater increase than can be expected in our aging population alone. Researchers believe this increase cannot be explained by an aging population alone and instead represents many modifiable risk factors including decreased exercise (Wallace et al. Proc Natl Acad Sci USA. 2017).

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