Variations in knee compressive force profiles in patients with osteoarthritis: the absence of the first peak in knee compressive force during walking

This study aims to investigate the gait strategies employed by some individuals with knee osteoarthritis (KOA) who walk without the first peak of the knee contact force (KCF). Additionally, it seeks to analyze the differences between those who walk with and those who walk without the first peak. In this cross-sectional study, 55 individuals with KOA were categorized into two groups (no first peak and two peaks). Gait data were collected with a motion capture system, and individualized musculoskeletal models calculated the KCF. MRI scans were performed to compare knee joint structures and scored using BLOKS. Twenty-two of the participants exhibited a gait pattern without the first KCF peak, while 34 displayed gait patterns with its presence. Those without the first peak pattern had higher body mass and BMI (P = 0.018 and P = 0.002, respectively), greater pain intensity (P = 0.002), worse KOOS scores for pain, daily activities, and sports/recreation (P ≤ 0.003), and walked more slowly (P < 0.001). They showed increased hip adduction early in stance, decreased internal rotation. Joint moments reflected reduced hip extension, increased abduction. Knee contact force was lower during loading response around the 1^st peak. No difference in knee structures was observed between the two groups. This study shows that people with KOA walking without the initial KCF peak experience worsened symptoms and distinct kinematic and kinetic adaptations compared to those who exhibit both peaks.