METHODOLOGY AND APPARATUS TO DETERMINE MATERIAL PROPERTIES OF THE KNEE-JOINT MENISCUS

This paper describes a soft tissue test method and apparatus which det ermines the constants necessary to characterise the elastic properties of a transversely isotropic material such as the knee joint meniscus. The tensile machine was designed to test small delicate samples in a humidified environment and measure specimen deformation with a CCD vid eo camera. The method described here employs a common specimen prepara tion procedure and test protocol using specimens with four different f ibre orientations. Discrete markers (0.075 mm graphite particles) perm it repeatable measurements of two-dimensional strain on the specimen s urface enabling the determination of Poisson's ratio characteristics. Shear strain was also measured in tensile test specimens prepared with an oblique collagen fibre orientation, offering an alternative method to investigate shear properties. Regional strain measurements provide an assessment of the uniformity of the tissue deformation. Preliminar y results on bovine menisci are presented as an application of the tes t system. Material properties characterising the meniscus tissue were obtained with one test procedure and identical coupon size. This has t he advantage of avoiding systematic errors caused by different prepara tion techniques, test procedures and equipment. (C) 1997 IPEM. Publish ed by Elsevier Science.