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Knee Osteoarthritis Impacted By Quadricep Strength

February 23, 2017
At the Association of Academic Physiatrists annual meeting, reseachers suggested that lower quadriceps speed may be associated with a decline in physical function and could be used to predict disease progression in people at risk for or dealing with knee osteoarthritis.

Interview with Neil Segal, MD

Among individuals facing knee osteoarthritis (OA), thigh muscle strength is critical to maintaining independence and mobility. As such, a loss of quadricep control has been linked to a decline in physical function. This was the focus of a presentation at the Association of Academic Physiatrists’ annual meeting, in Las Vegas, Nevada, that pointed to findings in which a standardized measure of quadriceps speed may be used to predict an individual’s risk of worsening physical function.1

In this study,1 led by Neil Segal, MD, a professor of Rehabilitation Medicine at the University of Kansas in Kansas City, found that a higher quadriceps speed at baseline was associated with a reduced risk of self-reported decline in physical function in individuals with, or at risk for, knee OA.

Conversely, lower speed of quadriceps muscle activation predated worsening of physical function over a 3-year follow-up period. “This finding is important for rehabilitation because we now know that in addition to higher quadriceps strength lowering risk for knee joint worsening, the speed of muscle activation is important to protect physical function,” Dr. Segal told Practical Pain Management.

Strength of thigh muscle may predict development of OA

At the study outset, the speed of force production (SFP) of the quadriceps, the muscles responsible for straightening the leg, was calculated using a chair specially designed to measure isometric strength (the force produced against a fixed object).1 Participants’ knees were held at a 60-degree angle, while seated in the chair, and they are asked to push as hard as possible against a bar calibrated to measure the force produced. The SFP measures at baseline were then divided into tertiles, reflecting low, middle, and high SFP.

Dr. Segal and his team anticipated that a low SFP at baseline would arise as a risk factor for worsening of physical function, as assessed by participant self-reports on a health status questionnaire (WOMAC-PF).2

At the 3-year follow-up, 3,608 of the original 4,255 eligible participants were included in the statistical analysis. Participants were excluded if, during this period, they had a knee injury, they developed rheumatoid or inflammatory arthritis, or they had a hip replacement.1 At 36 months, a decline in 9 or more points on the health status questionnaire was defined as worsening physical function.

Logistic regression was used to evaluate the association between SFP tertiles and worsening physical function, after adjusting for baseline age, sex, body mass index (BMI), and knee pain. Compared to participants in the lowest tertile of SFP, those in the middle and highest SFP tertiles had significantly less worsening in their self-reported physical function scores, indicating a lower risk for knee OA (OR, 0.79; 0.68, respectively). In addition, a subanalysis of results by gender indicated that women were the main drivers behind these results. Women in the highest SFP tertile had the lowest risk of worsening physical function (OR, 0.60). 

Results Support the OAI Findings

The authors concluded that lower speeds of force production by the quadriceps muscles may predate worsening of self-reported physical function,1 adding to the results of the United States Osteoarthritis Initiative (OAI), a partnership between the National Institutes of Health and private industry. The OAI is a multicenter, longitudinal, prospective clinical trial that has been providing information on the progression of knee osteoarthritis in a cohort of 4,796 men and women.3

Trial participants either had symptomatic knee OA at the time of enrollment or were at risk of developing the condition. These individuals had any of the following criteria—overweight status, history of knee injury or surgery, complaints of knee pain during the past year, and/or had a parent or sibling who had undergone knee replacement.

The OAI, completed in 2015, produced a public access resource to better predict the progression of OA and steer the development of new treatments to slow progression of or modify, this disabling disease, which affects more than 15 million people in the United States. 

Last updated on: June 2, 2017
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