Evidence for the local denaturation of collagen fibrils during the mechanical rupture of human tendons.

The ends of ruptured human tendons have been examined by scanning electron microscopy. The collagen fibres taper markedly, often leading up to a coiled segment or a knot of collagen at the point of rupture. This tapering of the collagen fibres was shown to be typical of denatured collagen by its selective removal by trypsin digestion. This denaturation caused by mechanical rupture was shown to be localized at the point of rupture, the rest of the collagen fibre remaining in the native state. The possible significance of these observations to the healing of ruptured tendons is discussed.