Background: Pain-related avoidance of activities is hypothesized to lead to lower muscle strength and thereby activity limitations. Negative affect (e.g., low vitality, depression) is thought to strengthen the tendency to avoid activities.
Purpose: The aim of this study was to assess the validity of this "avoidance model" in patients with early symptomatic knee osteoarthritis (OA).
Methods: Cross-sectional data (n=151) were used. The associations between pain, negative affect, avoidance, muscle strength, and activity limitations were modeled using structural equation modeling.
Results: Pain and negative affect were associated with lower muscle strength via avoidance (mediation by avoidance). Avoidance was associated with activity limitations via lower muscle strength (mediation by muscle strength). There were also direct associations between pain, negative affect, avoidance, muscle strength, and activity limitations.
Conclusions: The results support the validity of the avoidance model, which explains the associations between pain, negative affect, avoidance, muscle strength, and activity limitations in patients with early symptomatic knee OA.