Systemic versus local patterns of limb joint articular morphology inferred from relative distances from morphological centroid.

ABSTRACT

Joint morphogenesis is a complex process known to require the interaction of developmental cascades and mechanical loading, yet many details of this interaction are incompletely understood. While prior work has established populational patterns of joint morphological (co)variance, exploring how these patterns manifest within the individual provides information on the deployment of morphogenic processes as either systemic or local influences on joint shape. To better identify the patterns of variance-generating morphogenic processes, this study investigates the degree to which individual joint shapes deviate from population averages systematically across the body. Using three-dimensional landmark data from 200 adult skeletons, we ranked individuals based on their distances from morphological centroids for eight major joints. Spearman correlations assessed associations between ranks across various articular pairings, testing hypotheses regarding systemic versus localized variance. Results reveal low coordination between deviations observed in conarticular surfaces, functional analogs, and same-bone surfaces; however strong associations exist between antimeres, suggesting the left-right deployment of variance-generating morphogenic patterns is highly consistent. These results support a model of localized rather than systemic processes driving variation in joint shape. While more remains to be elucidated about the specifics of articular surface morphogenesis, these findings advance our understanding of the systems of variance generation at play during development and growth of our definitive joint morphology.