A study of the rabbit metatarsophalangeal joints with arthroplasty surface and normal articular cartilage was done by using compression testing to compare the elastic and viscoelastic behaviors of these two surfaces. Consistent differences were observed.
Articular cartilage exhibited less instantaneous deformation than the arthroplasty surface, that is, the cartilage was stiffer.
Both the rate and magnitude of time-dependent deformation under constant load (creep) of the articular cartilage were less than that of the arthroplasty surface. These differences increased significantly as a function of load. However, within the range of three to twelve-month-old anthroplasties, the viscoelastic behavior remained approximately constant.
Mechanical analogues were constructed in an attempt to characterize the physical behaviors of these tissues, and mathematical relations of the experimental data to the analogues were developed.
The loading range used in this study was not felt to exceed physiological limits as no plastic or permanent deformation was observed. Our findings show that cartilage is superior to the anthroplasty surface for resistance to and for recovery from the repetitive and rapid deformations which might be experienced in normal joint function Clinical experience supports this finding.
The difference in elastic and viscoelastic behaviors was related to histological and biochemical differences of the two surfaces.