Joint contact mechanics are important to the study of cartilage health and disease. Risk factors such as aging are speculated to result in altered cartilage contact locations, magnitudes, and sliding velocities, leading to altered loading of typical cartilage contact and non-contact areas. Altered contact patterns are speculated to be an influential mechanism associated with osteoarthritis-related cartilage changes such as softening, stiffening, or swelling. It is unknown whether knee joint contact patterns differ in an asymptomatic aging population compared to their younger counterparts.

This feasibility study aimed to enhance understanding of relations amongst contact mechanics, cartilage health, and functional status and aging. This work applied high-speed biplanar videoradiography and magnetic resonance imaging to non-invasively measure a weighted centroid (WC) of tibiofemoral cartilage contact during gait in participants between the ages of 20-30 years (n = 5), and 50-60 years (n = 5). Cartilage contact regions during walking were linked to cartilage-health imaging outcomes (i.e., T2 relaxometry).

Assessment of techniques for calculating the WC revealed that interval-based weighting factors provided the optimal approach, showing low sensitivity to errors but high sensitivity to clinically relevant changes. In aging vs. younger participants, no significant differences were found in WC location (median difference between heel strike and first force peak of gait cycle:​ younger 5.21-9.69%, older 2.12-7.44%), sliding distance (at onset of terminal swing:​ younger 0.50-1.15 mm, older 0.74-1.84 mm), or phase plot slope (change in sliding velocity over the surface of the joint;​ for swing phase:​ younger 4.14-14.99 mm/s%, older 6.15-14.47 mm/s%). For the first time, a functional relationship was found between T2 relaxometry and the gait cycle with lower T2 values during stance compared to prior to terminal swing. No differences were detected (younger vs. older) in T2 relaxometry values (medial tibial compartment at first force peak of gait:​ younger 29.8-43.1 ms, older 31.0-37.6 ms).

These findings could not support differences in contact mechanics in older asymptomatic tibiofemoral joints compared to younger joints. Nevertheless, some potentially atypical patterns in older participants provide motivation to better understand linkages amongst aging, contact mechanics and cartilage health status across the cartilage degeneration spectrum.