Effect of creep loading on the nanostructure of tendons

Abstract

This thesis focused on exploring ultrastructural damage to tendons during low strain-rate loading at overload and suboverload levels. In the first experiment, tendons were either statically loaded at overload stress until rupture, ramp loaded to yield and then unloaded, or ramp loaded until rupture. In the second experiment, tendons were statically loaded at suboverloaded stress for different periods of time, after which they were unloaded. Structural assessments of loaded tendons and matched-pair controls were conducted using scanning electron microscopy and differential scanning calorimetry. Rupturing tendons at low strain-rate created significant ultrastructural damage to the packing of collagen molecules within fibrils. Only when rupture occurred during static loading, though, were significant quantities of denatured collagen created. Sustained loading at suboverload levels was found to disrupt collagen fibrils when applied for durations >2 hours.