Bilateral variation in limb articular surface dimensions.

Joint form is frequently used to interpret locomotor and manipulative adaptations and infer physical behavioral patterns in past humans, yet the precise genetic and environmental determinants of joint size are incompletely understood. The aim of this research is to assess the plasticity of limb articular dimension through the use of directional asymmetry as an indicator of mechanical stress during skeletal development. Directional asymmetry is largely attributable to differential mechanical loading during bone growth related to handedness. Because the large majority of individuals are right-handed, it is hypothesized that joint dimensions will be significantly larger in the upper right limb and lower left limb in the crossed symmetry pattern that is typically exhibited in bone lengths. Patterns of bilateral variation were explored by sex and skeletal location. Significant levels of directional asymmetry (P < 0.05) suggest that limb articular surfaces are adapted to the mechanical environment. Biomechanical factors are important in the development and maintenance of articular morphology. Further research, however, is needed to establish the exact relationship between joint size and the mechanical environment. Copyright 2004 Wiley-Liss, Inc.