Rotator Cuff Tendon Repair after Injury in Hyperlipidemic Swine Decreases Biomechanical Properties

Rotator cuff injury is the leading cause of shoulder pain. Hyperlipidemia is responsible in depositing lipids in tendons and reduce the healing upon injuries or tears. In this study, we created rotator cuff injury and repair models in swine and studied the changes in biomechanical properties of infraspinatus tensons in hyperlipidemic swine. The infraspinatus tendons from control group, hyperlipidemic injury and repair group of animals were collected and tested ex-vivo. The ultimate tensile strength (UTS) and modulus of elasticity increased in the tendons from the contralateral side on both the injury and repair models were higher than the injury side. The presence of large number of fibrous tissues in the surgical site of repair and increased water content was observed in addition to the fatty infiltration which would have contributed to the decreased mechanical properties of the inured tendons following repair. Meanwhile the tendons of the contralateral side in both the injury and repair model showed adaptation to chronic load as observed in the modulus and viscoelastic properties. This is a pilot study that warrants detailed investigation in a larger sample size with longer duration following tendon injury and repair to gain better understanding on the effect of hyperlipidemia in the healing of rotator cuff tendon injury.