Dynamic contact stress patterns on the tibial plateaus during simulated gait: a novel application of normalized cross correlation.

The spatial distribution and pattern of local contact stresses within the knee joint during activities of daily living have not been fully investigated. The objective of this study was to determine if common contact stress patterns exist on the tibial plateaus of human knees during simulated gait. To test this hypothesis, we developed a novel normalized cross-correlation (NCC) algorithm and applied it to the contact stresses on the tibial plateaus of 12 human cadaveric knees subjected to multi-directional loads mimicking gait. The contact stress profiles at different locations on the tibial plateaus were compared, where regions with similar contact stress patterns were identified across specimens. Three consistent regional patterns were found, among them two most prominent contact stress patterns were shared by 9-12 of all the knees and the third pattern was shared by 6-8 knees. The first pattern was located at the posterior aspect of the medial tibial plateau and had a single peak stress that occurred during the early stance phase. The second pattern was located at the central-posterior aspects of the lateral plateau and consisted of two peak stresses coincident with the timing of peak axial force at early and late stance. The third pattern was found on the anterior aspect of cartilage-to-cartilage contact region on the medial plateau consisted of double peak stresses. The differences in the location and profile of the contact stress patterns suggest that the medial and lateral menisci function to carry load at different points in the gait cycle: with the posterior aspect of the medial meniscus consistently distributing load only during the early phase of stance, and the posterior aspect of the lateral meniscus consistently distributing load during both the early and late phases of stance. This novel approach can help identify abnormalities in knee contact mechanics and provide a better understanding of the mechanical pathways leading to post-traumatic osteoarthritis.