The Role of Pain Sensitization and Muscle Function in Knee Osteoarthritis Mechanics

Abstract

Knee osteoarthritis (KOA) pain is frequently in discordance with structural severity, suggesting sensitization mechanisms. However, the relation of pain sensitization with functional demand and properties remains unexplored, neglecting age-related differences. This thesis investigated associations of pain sensitization with functional demand (muscle capacity utilization; MCU), and muscle stiffness (shear wave velocity; SWV) in individuals with KOA, exploring age-related differences. Thirty-one adults with unilateral KOA completed self-reported questionnaires, quantitative sensory testing, strength testing, gait analysis, and quadriceps ultrasound elastography. MCU was calculated during walking and stairs. Pain sensitization was bilateral despite unilateral KOA. MCU was higher in the contralateral limb across tasks. Sensitization and MCU were negatively associated. Quadriceps SWV was moderately associated with sensitization in the affected limb. Sensitization-MCU associations were stronger in younger participants during stairs, and in older adults during walking. Pain sensitization may contribute to age-related functional compensations in KOA, highlighting the need for interventions tailored to symptoms.