Background/Purpose: Following total knee replacement (TKR), patients do not achieve recommended physical activity for overall health. The implications of physical inactivity on individuals and the healthcare system are substantial and well documented, yet why these patients do not achieve recommended levels are not well understood. The concept of physical literacy – if people have the knowledge, competence and confidence to undertake physical activities effectively to reach optimum levels of performance – has not been explored in an adult population. Given the grave health implications associated with physical inactivity, this study aimed to examine physical activity levels and potential factors, including physical literacy, that may influence activity levels in this population.

Methods: This study used a prospective observational design and included people having primary TKR for osteoarthritis.The primary outcome was change in physical activity as measured by the Rapid Assessment of Physical Activity survey tool. To examine predictors of physical activity levels, we evaluated the following: age, sex, BMI, comorbidity count, Patient Health Questionnaire Depression Scale, Pain Disability Index, P-4 pain intensity measure, Arthritis Self-Efficacy Scale, and Adult Physical Literacy Assessment.The physical literacy measure evaluates the domains of environment, self-efficacy, and relative rankings of literacies. We hypothesized differences in the amount of physical activity relating positively or negatively to the predictive factors. Standard definitions described categorical variables. Continuous variables were categorized according to the results of Shapiro Wilks and Kolmogrov tests. We compared changes in outcome measure scores using percentage or mean change. The statistical significance of changes was assessed using McNemar’s test or a paired t test. Lastly, predictors of physical activity at 12 months were assessed using regression models as determined by assessments of normality and verification of assumptions.

Results: The sample included 104 patients; male (31%) and female (72%) with ages ranging from 52-87 years. Physical activity levels were different between T1 and T2 in some participants. There was a significant change in aerobic activities with a small effect size. There was no significant change in strength and flexibility. Age, sex, comorbid illness and depression did not predict aerobic change. However, changes in self-reported measures of physical activity (p=0.02) and depression (p=0.001) were significant from Time 1 to Time 2. Physical literacy scores were not predictive of physical activity scores. However, those who reported lower physical literacy scores also reported lower physical activity scores and those with higher physical literacy reported higher physical activity scores.

Conclusion: As in other studies, individuals who are active prior to surgery resume activity and those who are not active prior to surgery do not increase their activity after surgery. Physical literacy introduces a novel concept that seems to be related to activity level. Future studies should further evaluate this concept as it may be a target for enabling people to be physically active.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/exploring-possible-predictors-of-physical-activity-in-knee-replacement-patients/