A portable arthroscopic diagnostic probe to measure the viscoelasticity of articular cartilage

Tissue engineering has been increasingly applied to treat diseases of the joints that adversely affect components such as cartilage and ligaments. These components do not contain blood vessels and nerves; the risk of rejection during tissue transplantation is therefore less than that for other organs. Treatment of cartilage and ligaments requires highly skilled surgeons, however, and it is necessary to establish a quantitative evaluation method. It is difficult to measure the mechanical properties of cartilage because of its viscoelasticity. Sensing technology that enables uniform qualitative evaluation is therefore desired. In this study, a portable diagnostic probe was developed and the viscoelasticity of cartilage was measured quantitatively over a short period of time. The probe was designed based on the Voigt model and comprises a piezoelectric actuator, a force sensor, and a contact probe. Stiffness and viscosity coefficients of various samples such as silicone rubber and the bovine meniscus were measured, and the accuracy of the developed probe was evaluated. Finally, the mechanical properties of human articular cartilage were measured using the diagnostic probe.