A study of the normal range of strain, strain rate, and stiffness of tendon.

This paper describes the result of an investigation of strains and strain rates which normally occur in the tendons of the equine foreleg and presents stress-strain curves and moduli for the tendons at these rates. It has previously been demonstrated that resistance to flexion of the joints of the distal part of the equine foreleg is provided by a passive system of tendons and ligaments. It is therefore possible, using a large displacement, high-rate testing machine, to duplicate in the laboratory the strain rates and forces which are normally produced in the tendons of the foreleg of the running horse. To carry out tendon tests, legs were mounted in the test machine. The superficial flexor tendon was exposed and fitted with an extensometer and a buckle-type force transducer. Stress-strain curve were obtained for 13 tendons. It is shown that strains to 12% and strain rates to 200%/sec occur normally in the superficial flexor tendon. Stress strain curves and tangent modulus are presented for strains from 0 to 10% at rates from 5 to 100%/sec. Tendon modulus is found to be essentially rate in dependent in this range.