Association between center of pressure parameters and self-reported factors in osteoarthritis across age and BMI: a cross-sectional study in East Azerbaijan, Iran

Abstract

Knee osteoarthritis (KOA) is a common degenerative joint disease, especially in older adults, affecting postural stability and center of pressure (COP) behavior. These biomechanical parameters may vary by age, gender, and body mass index (BMI). This study aimed to explore the relationship between COP features and these individual factors, along with self-reported pain and function, in people with KOA. From a cohort of 4355 individuals in East Azerbaijan, 333 self-reported a physician diagnosis of KOA. After excluding cases with comorbidities, 75 participants were included. Pain and function were assessed using the WOMAC and visual analog scale (VAS), while COP metrics were collected using a PT-Scan® pressure platform. One-way ANOVA and Pearson correlation were used for analysis. Age demonstrated positive relationships with Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) subscales in men (Pain LSD = 341.16, p < 0.001; Total LSD = 2333.69, p < 0.001 and Functional LSD = 1391.6, p < 0.001). In women, age showed positive effects on WOMAC Total (LSD = 60.00; p < 0.05). BMI showed negative effects on WOMAC Stiffness in both genders (Men LSD = 125, p < 0.001; Women LSD = 150, p < 0.001). In examining the relationship between the characteristics of the COP and age in women, a significant relationship was seen between age and a number of characteristics of the COP, including anterior–posterior range (AP-Range-R), mediolateral range (ML-Range-L), and the area of the confidence circle (AREA_CC_L). Examining the correlation between the characteristics of pain and the COP, a significant negative correlation was found between VAS and the characteristic of the COP (fractal dimension (FD_CE_L)). In women. These results highlight the need for age- and gender-specific approaches in evaluating balance and function in KOA.