Hyperlipidemia Lowers the Biomechanical Properties of Rotator Cuff Tendon

Infraspinatus tendon is the most affected tendon of the rotator cuff, being an important posterior component of the shoulder joint. Hyperlipidemia is a predisposing factor in the progression of rotator cuff tears and retear. We studied the effect of hyperlipidemia on the biomechanical properties of rotator cuff tendons. The infraspinatus tendon of the rotator cuff from hyperlipidemic swine were collected and tested for ultimate tensile strength (UTS) and modulus of elasticity. Dynamic mechanical analysis was performed to examine viscoelastic properties. The findings revealed no significant difference in UTS but had significantly lower modulus of elasticity in the infraspinatus tendon of the hyperlipidemic group compared to the control group. Moreover, differences in the dynamic modulus, storage modulus, and loss modulus were not statistically significant between the hyperlipidemic and control swine. There was no difference in water content between the groups but the hyperlipidemic group had fatty infiltration aiding the initial decrease in mechanical properties. These findings suggest an association between fat deposition and early changes in the biomechanical properties of the tendons in the shoulder rotator cuff in hyperlipidemic state.