Background/Purpose: Depression is associated with low physical activity (PA) levels in people with knee osteoarthritis (KOA)1. Pain contributes to both depression and PA levels in people with knee OA1,2 but can also influence gait biomechanics which may, in turn, adversely impact PA. Understanding how depression, pain, gait biomechanics, and PA are interrelated in KOA could guide more effective interventions. This study, therefore, investigated the relationships among these factors. We focused on joint powers as a relevant aspect of gait biomechanics because they are directly related to force absorption and generation during motion and may be directly related to the ability to be physically active. We hypothesized that (i) depression, pain, and affected limb hip, knee, and ankle joint powers are all associated with PA, and (ii) that more depression and pain are associated with lower joint powers.

Methods: We evaluated 34 people with knee OA (20 Women, 56±8 years, 34.7±7.1 kg/m2) walking at self-selected speeds on an instrumented split-belt treadmill, using standard motion capture methods. We calculated sagittal plane peak positive joint powers of the hip, knee, and ankle during terminal stance. Participants reported their PA levels using the UCLA activity scale which ranges from 1 (“wholly inactive”) to 10 (“regularly participate in impact sports”). Participants also completed the KOOS pain subscale, where 100 indicates the absence of pain and the PROMIS Depression Computerized Adapted Test, (US average = T score of 50, higher scores indicate more depression). We used Spearman correlations to quantify the associations among variables.

Results: Surveys indicated that, on average, participants were moderately active (UCLA 5±2), reported an average level of depression symptoms (T score 50±11) and reported moderate pain (KOOS Pain 54.0±22.6). UCLA scores were significantly correlated with pain, depression, and all joint powers (Table 1). More depression and pain were associated with lower PA levels but, surprisingly, depression and pain were not correlated with each other. Finally, more pain was associated with lower joint powers but there were no associations with depression.
These findings support our hypothesis that depression, pain, and joint powers are associated with PA levels in KOA. Pain may lower PA levels directly as well as indirectly through its influence on joint mechanics. Hip and ankle powers had moderate to strong associations with PA indicating the need to include a multi-joint rehabilitative strategy to preserve power generation along the entire kinetic chain, rather than the knee only. Further, the association of PA levels with depression amplifies its independent importance. Multi-factored interventions that include depression management may be helpful to improve PA in this population.

Conclusion: There is an interplay of psychosocial and structural factors that influence PA in people with knee OA. Effective clinical intervention should include a well-defined holistic approach.

Spearman correlation coefficients and p values quantifying associations among PA levels, joint powers, pain, and depression in people with knee OA. Greater joint powers, less pain, and less depression are associated with higher levels of PA. Shading highlights statistically significant correlations.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/interrelationships-of-depression-pain-and-gait-mechanics-and-their-associations-with-physical-activity-levels-among-people-with-knee-osteoarthritis/