Morphological Plasticity in the Juvenile Talus

BackgroundLittle is know about the effects of the changing body weight on the juvenile skeleton and to what extent it can explain the phenotypic variability observed in human joint morphology. The talus occupies a pivotal position and must sustain and distribute the weight of the body without deformation and whilst remaining a functional biomechanical unit. It is hypothesized that the talus exhibits morphological plasticity of its articular surfaces in order to adapt to the increases in body weight associated loading over ontogeny.ObjectivesTo explore plasticity in talar articular facet morphology during development in response to increases in body weight.MethodTali from juvenile archaeological remains from 8 to 18 years of age were cast, then laser scanned and homologous landmark data were acquired by a novel method and utilized in 3D geometric morphometric analysis. Femur length was used as a proxy for individual body weights.ResultsChanges in shape and orientation of three talar articular facets was observed over ontogeny. Principle components 1, 2, 3 and 5 correlated significantly with increases in body weight.ConclusionsTalar articular surface morphology is plastically adaptive to changes in body weight over ontogeny. A framework of normal ontogenetic changes over the juvenile period is provided for practitioners.