EARLY-STAGE knee osteoarthritis may involve knee underloading, with lower second contact force peaks during barefoot walking.
Knee Osteoarthritis Loading Patterns in Early Disease
Altered joint loading is often discussed as a driver of osteoarthritis progression, but whether early-stage disease already shows distinct mechanical phenotypes remains uncertain. In a cross-sectional observational study, researchers compared gait pathomechanics in early-stage knee osteoarthritis across two subgroups: post-traumatic knee osteoarthritis (PTOA) and non-traumatic knee osteoarthritis (NTOA), alongside age- and gender-matched healthy controls.
The study included 22 participants with early-stage PTOA, 26 with early-stage NTOA, and 20 controls. All participants walked barefoot at self-selected speeds while investigators collected marker-based motion data, ground reaction forces, and surface electromyography. Electromyography-informed musculoskeletal simulations were then used to estimate knee contact forces (KCF) and related joint mechanics. Group differences were evaluated using Statistical Parametric Mapping, and analyses also examined the influence of key covariates, including gait speed, alignment, and strength.
Similar Mechanics in Post-Traumatic and Non-Traumatic Groups
Across the two early-stage patient groups, findings suggested broadly similar knee loading profiles. Specifically, early-stage NTOA and PTOA participants demonstrated comparable KCF and joint mechanics overall, with no clear separation into distinct gait phenotypes during the walking task used.
However, both patient groups showed significantly reduced second KCF peaks compared with controls. The authors interpret this as evidence of knee underloading in early-stage knee osteoarthritis, contrasting with the joint overload patterns more commonly associated with established osteoarthritis.
Why Gait Speed Matters
Gait speed emerged as an important influence on KCF peaks, underscoring how walking behavior can shape measured joint loading. The investigators suggest that early osteoarthritis may be characterized by cartilage underloading, and that longitudinal follow-up and more demanding functional tasks could help clarify whether phenotype-specific biomechanical distinctions emerge over time and whether underloading persists with disease progression.
Reference: Vanmechelen A et al. Gait pathomechanics in early-stage knee osteoarthritis: do non-traumatic and post-traumatic patients walk differently? J Electromyogr Kinesiol. 2026;87:103113.
