Abstract:

BACKGROUND: Similar to other soft tissues, ligament has viscoelasticity. The stress relaxation and creep viscoelasticity of ligaments are based on human physiologic functions. Studies have demonstrated that osteoarthritis has effect on ligament mechanical property.
OBJECTIVE: To compare stress relaxation rheological properties of medial collateral ligament (MCL) between normal and osteoarthritis animal models, to determine the influence of osteoarthritis on MCL ligament stress relaxation characteristics.
METHODS: Animal osteoarthritis models were prepared by closed joint Nick method. Each 10 MCL samples were taken from normal and osteoarthritis rats for stress relaxation experiments. The strain increase rate was 5%/s, and test duration was 7 200 s, a total of 100 data were collected. The stress relaxation data, and change laws of curves, stress and time were observed. All data were analyzed by one linear regression.
RESULTS AND CONCLUSION: The stress relaxation of the normal and model groups changed fast at the initial 600 s, followed by a slow decrease. The stress relaxation of the normal group at 7 200 s was 4.69 MPa, and the model group was 0.29 MPa. The 7 200 s stress relaxation quantity of the model group was obviously smaller than that of the normal group (P < 0.05). The stress relaxation curves were changed in a log relationship. The knee osteoarthritis can decrease MCL stress relaxation, which influences LCL stress relaxation characteristics.