Population-based analysis of knee joint loading in a knee osteoarthritis cohort: the impact of PCA-derived gait kinematic variations on estimated medial knee contact forces

Osteoarthritis (OA) is a prevalent musculoskeletal condition leading to functional limitations, especially among the elderly. Current treatments focus on pain relief and functional improvement, however there is a lack of approaches which slow disease progression. A promising approach focusses on reducing knee joint loading, as excessive loading contributes to knee OA progression. This study explores kinematic variations in the knee OA population, utilizing principal component analysis (PCA) to examine gait variations (primitives) in both healthy individuals and those with knee osteoarthritis (KOA) and their implications for knee joint loading. The KOA population exhibited 14 modes of variation representing 95% of the cumulative variance, compared to 20 in the healthy population, indicating lower variability with KOA. The relation between identified gait primitives and knee loading parameters, revealed complex relationships. Surprisingly, modes with the largest kinematic variations did not consistently correspond to the highest variations in knee loading parameters revealing degrees of freedom which may have a larger role in determining joint loading. Moreover, potential gait-retraining strategies for KOA, associating specific kinematic combinations with altered knee loading were identified. The results showed a good agreement with previously applied strategies. However, this study highlights the importance of analyzing whole-body kinematics for effective gait retraining, as opposed to focusing on one single joint variation. The study’s insights contribute to understanding the intricate interplay between gait pattern variations and knee joint loading changes in healthy and KOA populations, offering practical applications for guiding interventions and estimating loading parameters. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This research was supported by KU Leuven PhD project 3M200591 as well as the Research Foundation Flanders FWO grant G0E4521N for collaboration with Laval University ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Ethical committee of Centre integre universitaire de sante et de services sociaux de la Capitale-Nationale, Quebec gave ethical approval for this work (reference number MP-13-2020-1954) I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes