Effects of a nineteenth century below‐knee amputation and prosthesis on femoral morphology

Access to the lower limbs from a historically‐identified nineteenth century below‐knee amputee who had worn a hardwood ectoprosthesis for an extended time prior to death provides a natural experiment for investigating the morphological and histological effects of the resulting altered mechanical environment. Osteometry (measuring total bone size), cross‐sectional geometry (bending and axial rigidity) and histology (bone turnover rate) are assessed. A reduction in size and geometric strength, along with an increase in cortical bone turnover, indicate that the midshaft and distal regions from the affected femur were partially shielded from functional strain. Structural compliance of the prosthesis, probably originating from design and material of manufacture, to some degree preserved the mechanical and morphological integrity of the proximal subtrochanteric region. The results of this case study are consistent with contemporary theory in skeletal biomechanics, for example, Frost's Mechanostat, which suggests that insufficient functional strain promotes intracortical remodelling and endosteal expansion.