Indentation of Articular Cartilage: Effects of Specimen Radius on Determined Properties

The indentation test is a commonly used experimental setup to determine properties of articular cartilage, both in the laboratory and as a clinical tool, as it is a test that can be performed in situ. Behavior of normal cartilage and tissue generated in reparative studies have been thus obtained [1, 2, 3]. It has been shown from a finite element study [4] that the behavior of cartilage in indentation stress relaxation can be affected by the tissue width relative to the radius of the indenter. Another finite element study of the indentation of osteochondral defects showed that this ratio also affected specifications of boundary conditions [5]. This investigation sought to evaluate the effect of changing geometric parameters (e.g. tissue width and indenter radius) on the properties determined from creep indentation experiments.