Interfragmentary Strain & Callus Differentiation

This simulator renders Perren's interfragmentary strain theory in 3D: a fractured long bone with an adjustable gap, stabilized by a chosen fixation method, under an adjustable axial load. Gap displacement and strain are computed from the combined stiffness of the fixation hardware and the growing callus, and a Gaussian mechanobiological growth window (peaking near moderate strain) determines how quickly — and into what tissue — the callus bridges the fracture, matching the clinical observation that rigid plating heals with minimal visible callus while flexible fixation produces a large external callus.