Combatting Sedentary Behavior in Patients With Knee Osteoarthritis or Replacement


Investigators set out to explore sedentary behavior, physical and mental limitations, the willingness of this patient population to engage in more regular exercise, how perceptive they were to using technology to support a more active lifestyle, and interventions to reduce sedentary time.

Although physical activity is beneficial for patients with symptomatic knee osteoarthritis (KOA) or those who have had a knee replacement, few individuals reach the recommended amount of activity. In a study published in ACR Open Rheumatology,1 investigators set out to explore sedentary behavior, physical and mental limitations, the willingness of this patient population to engage in more regular exercise, how perceptive they were to using technology to support a more active lifestyle, and interventions to reduce sedentary time.

A sedentary lifestyle increases the risk of a negative cardiometabolic profile and mortality. For patients with existing knee issues, it is associated with disability, impaired physical function, and poor quality of life. Nearly half of patients with KOA will need a knee replacement in their lifetime. Unfortunately, less than 20% of men and 10% of women with KOA meet the recommended guidelines for physical activity, either before or after knee replacement.

“The knowledge gained from this study can help to inform the development of future sedentary reduction interventions and patient‐centered clinician recommendations for those with symptomatic knee osteoarthritis or knee replacement,” investigators hypothesized.

Eligible patients were ≥50 years old, living in the southeastern United States, and were experiencing symptomatic KOA or had received a knee replacement. The study comprised a series of short online surveys, which took about 25 minutes to complete. Those who completed a survey were able to enter to win 4 $25 Amazon gift cards.

Patients reported basic information such as age, sex, level of education, ethnicity, and employment status. They completed a medical and surgical history survey and were asked about technology ownership and usage. Investigators utilized the Patient-Reported Outcomes Measurement Information System (PROMIS) to assess pain intensity and interference, as well as physical function and mobility. Levels of physical activity were examined using a modified version of the Godin Leisure Time Exercise Questionnaire, in which participants reported the frequency, strenuousness, and amount of time spent exercising over the past 7 days. Sedentary time was calculated using the Sitting-Time Questionnaire.

Additionally, patients were asked their opinions on sedentary behavior, including the potential benefits and harms of too much sedentary time, the maximum amount of sedentary time before standing, and their attitude towards their current level of sedentary time (eg, “I wish I could sit less” or “I wish I could sit more”). They also had to identify the factors that stopped them from standing up more frequently as well as how much control they had over these limitations. Lastly, the interest and preferences for “technology-supported sedentary behavior reduction intervention” was reported.

In total, 42 patients ≥50 (mean = 61.8 years; SD = 7.6 years) participated in the study. The 13 patients who had a knee replacement (31%) were older than those with KOA (66.8 years and 59.5 years, respectively). PROMIS results showed an average mobility score of 42.6 (SD = 2.3), pain intensity score of 55.1 (SD = 2.1), and pain interference score of 45.2 (SD = 2.8). In regard to access to technology, 98% of participants owned a computer, and 93% owned a mobile phone (87% of those with a mobile phone owned a smartphone). Additionally, 25% currently used an activity monitor.

Participants averaged 129.7 minutes/week of strenuous or moderate exercise and 10.9 hours/day of sedentary behavior. Only 29% of participants met or exceeded exercise recommendations (150 minutes/week), with one-third reporting no physical activity at all. However, 86% believed that a sedentary lifestyle is harmful and 83% reported that a reduction in sitting would improve health. More than half of participants (55%) wanted to sit less and the majority would be willing to replace sitting with 2-minute activities, including stretching and walking. Physical limitations included pain while standing (52%) and not being able to stand while using the computer (48%).

“This sample appears to have strong behavioral beliefs regarding the consequences of prolonged sedentary behavior; however, their perceived behavioral control over replacing sedentary time appears to decline with activities of longer durations and may depend on whether the sedentary behavior is at work or in their leisure time,” investigators explained. “As a result, intention or willingness to change or participate in a sedentary reduction program is lower than anticipated.”

Although the majority of participants didn’t fulfill the physical activity guidelines, 67% were interested in a sedentary behavior reduction program. They reported that the best way to reduce sitting time would be tracking/self‐monitoring (71%), daily goals (69%), and education (67%). Nearly half of participants (45%) were willing to receive reminders to stand, with 80% preferring them to be sent when sitting longer than 30 minutes to 1 hour.

Limitations to this study include the small survey sample of patients, which hinders generalizability. “Future studies should include a larger, nationwide sample to gauge preferences from a more diverse range of individuals as well as to compare any potential differences in preferences and beliefs toward reducing sedentary behavior between those with KOA and those with knee replacement,” investigators added. Further studies are needed to test the efficacy of the intervention methods to determine if they can reduce sedentary behavior in this patient population.

“Although an optimal level of sedentary behavior reduction to decrease disease risk is unknown, this study suggests that disseminating knowledge regarding ways to reduce sitting time could be a logical first step for decreasing sedentary behavior and health risks,” investigators concluded. “However, future research is also needed to identify strategies to increase intention to reduce sedentary time in those with KOA or knee replacement.”


Powell SM, Larsen CA, Phillips SM, Pellegrini CA. Exploring Beliefs and Preferences for Reducing Sedentary Behavior Among Adults With Symptomatic Knee Osteoarthritis or Knee Replacement [published online ahead of print, 2021 Jan 5]. ACR Open Rheumatol. 2021;3(1):55-62. doi:10.1002/acr2.11216

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