First Metatarsophalangeal Joint Motion in Homo sapiens: Theoretical Association of Two-Axis Kinematics and Specific Morphometrics Michael N. Durrant, Tucker McElroy, and Lara Durrant J Am Podiatr Med Assoc 2012;102 374-389 Quote: Background: The metatarsal head and proximal phalanx exhibit considerable asymmetry in their shape and geometry, but there is little documentation in the literature regarding the prevalence of structural characteristics that occur in a given population.
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Two axes first MPJ model