Low tension studies of collagen fibres from ligaments of the human spine.

On polarization microscopy collagen fibres from human cadaveric anterior longitudinal, posterior longitudinal, and interspinous ligaments show a series of transmission and extinction bands. By observing changes in this pattern on rotating the polarizing stage and on rotating the fibres a crimped structure of the fibres was deduced and its parameters were calculated. From these data the force/strain behaviour of the fibres under low tension was calculated. This corresponded closely with the results from mechanical measurement. At the same time we documented alterations in the transmission and extinction patterns while under tensile load. The results suggest that it is the crimped structure that is responsible for the high extensibility of the collagen fibres under low tension. The initial extension is by deformity of the crimp segment. This avoids risk of tearing the collagen fibres.