Stress-strain characteristics of in situ frozen and stress-shielded rabbit patellar tendon.

Abstract

To assess the effects of stress shielding on the stress-strain behaviour of the in situ frozen tendon, which simulates an ideally oriented autogenous graft, patellar tendons (PT) of 26 Japanese white rabbits underwent in situ freezing with and without the stress shielding treatment. The patella-PT-tibia complexes excised at 3 and 6 weeks postoperatively were loaded between 0% and 3% strain. The material constants were computed by fitting the data to a constitutive equation. The material constants showed that the initial slope of the stress-strain curve of the group without stress shielding was significantly steeper than that of the group with stress shielding at 3 weeks, but not at 6 weeks. The increase in the slope of the stress-strain curve of the group without stress shielding was significantly more than that of the group with stress shielding at both 3 and 6 weeks.