Self-reported and dynamic knee joint stiffness during stair climbing in females with patellofemoral pain and their relation to joint load

Abstract

Patellofemoral pain is a common and costly musculoskeletal disorder that encompasses men, women and adolescents. Although the dominant symptom is pain around and behind the patella, patients also describe patellofemoral crepitus, knee stiffness and poor quality of life. Individuals with PFP often complain of knee joint stiffness after prolonged periods in knee flexion and a possible relationship among pain, knee joint stiffness and the progression of rheumatic diseases may exist. However, it remains unknown whether the knee is physiologically stiffer in individuals with PFP. Therefore, the aims of this study are to investigate differences in stair climbing knee stiffness in females with and without PFP, and to investigate the construct validity of stair climbing knee stiffness as being related to the recognized measures of self-reported knee stiffness in females with PFP. Secondary aims are to investigate in females with PFP the extent to which knee flexion excursion and knee extensor moment contribute to stair climbing knee joint stiffness, and to examine the relationship between stiffness (self-reported and dynamic stiffness) with markers of joint loading (rate of loading and peak knee abduction moment). Twenty-one females with PFP and twenty-one asymptomatic controls will be recruited to participate in the study. Self-reported knee stiffness will be obtained with WOMAC and visual analogue scale. Dynamic knee stiffness will be calculated during stair climbing as the change in knee flexion-extension moment divided by the change in knee flexion angle. In addition, peak knee abduction moment and rate of loading of ground reaction force will be obtained and used as markers of joint loading. Independent t tests will be used to compare dependent variables between the groups. Forward-stepwise regression models and Pearson's correlation coefficients will be used to evaluate the relationships between variables. (AU)