Prefrontal cortex activation during daily movements and its association with clinical symptoms in knee osteoarthritis.

Objective: For people with knee osteoarthritis (OA), step-up is one of the most physically demanding and pain-evoking daily movements. Given the significant role of the prefrontal cortex (PFC) in executive function and pain modulation, our objectives were (1) to assess PFC activation during walking and step-up in people with knee OA and (2) to examine the association of pain and psychological outcomes with changes in PFC activation from walking to step-up.

Design: This cross-sectional study included 44 individuals with symptomatic knee OA. Participants completed Knee Injury and Osteoarthritis Outcome Score (KOOS), Pain, Enjoyment of Life, and General Activity (PEG) scale, Patient Health Questionnaire (PHQ-8) for mood, 3-item Pain Catastrophizing Scale (PCS), and Fear-Avoidance Beliefs Questionnaire (FABQ). Oxygenated hemoglobin concentration changes (HbO) in the bilateral PFC were assessed using functional Near-Infrared Spectroscopy. HbO were compared between tasks using repeated measures ANCOVA. Multiple linear regression models tested the association between clinical outcomes and changes in HbO from walking to step-up while adjusting for confounders.

Results: HbO during step-up was higher compared to walking, with moderate effect size ( ​= ​0.3-0.5). Greater pain catastrophizing (R ​= ​0.10) was correlated with smaller changes in HbO from walking to step-up.

Conclusion: People with knee OA utilized greater executive control during step-up compared to walking. Similar to stair climbing, step-up is more physically demanding and more frequently impaired than walking. Greater pain catastrophizing was related to smaller increases in PFC activation from walking to step-up, reflecting the availability of fewer executive resources to maintain task performance.