Abstract 39

VARIATIONS IN MECHANICAL PROPERTIES ALONG THE LENGTH OF THE EXTRAMUSCULAR TIBIALIS ANTERIOR TENDON

Vizesi, F; Gandevia, S; Walsh, W R

Orthopaedic Research Laboratories, University of New South Wales, Prince of Wales Hospital, Sydney, NSW, Australia

This study investigates variations in the biomechanical properties of the extramuscular tibialis anterior (TA) tendon from proximal to distal by mechanical testing of specimens from sheep. Particular emphasis is placed on the toe-region of the stress-strain curve as this is where the tendon is believed to operate under physiological conditions and for which there is limited published work.

TA tendons were harvested from the hind legs of mature wethers and cut down into three regions of interest: A (distal), B (central) and C (proximal). Each sample was tested with a constant force of 1N and allowed to creep for 600s to accommodate the majority of tissue viscoelasticity. A sample size of n=9 was employed for each region. The samples were tested at room temperature with regular spraying of phosphate buffered saline to maintain moisture levels and cell viability. The biomechanical properties measured were stiffness and Young's Modulus.

The central region of the TA tendon was significantly stiffer than the proximal and distal regions by more than a factor two. The cross sectional area of regions A, B and C were not significantly different, so the pattern of Young's Modulus was similar to the stiffness. In all cases, statistical significance was established between regions using ANOVA with P<0.02. Under physiological conditions, the tendon is normally loaded in the low strain region and therefore it is important to consider the mechanical properties under these conditions. The results shown here may be considered for modelling of muscles and joints and for development of tendon prostheses that should have comparable mechanical properties to the native tissue.

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