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. 2023;5(4):398-405.
doi: 10.26502/josm.511500127. Epub 2023 Oct 23.

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

Lal L P Merlin Rajesh  1 , Mohamed M Radwan  1 , Finosh G Thankam  1 , Devendra K Agrawal  1
Affiliations

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

Lal L P Merlin Rajesh et al. J Orthop Sports Med. 2023.

Abstract

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 tendons 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 and 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 injured 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.

Keywords: Biomechanical properties; Dynamic modulus; Hyperlipidemia; Infraspinatus tendon; Rotator cuff injury model.

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Conflict of interest statement

Competing interest: All the authors have read the manuscript and declare no conflict of interest. No writing assistance was utilized in the production of this manuscript.

Figures

Figure 1:
Figure 1:
Mechanical properties and water content of tendon tissues. (A) Ultimate tensile strength, (B) Modulus of elasticity, (C) % Failure strain, (D) Water content. Control indicates the group of swine that received normal diet and no surgery. Surgery CS indicates uninjured tendon from contralateral side of swine that underwent either injury or injury + repair surgery. Injury IS indicating tendon from injury side that underwent injury. Injury + Repair IS indicating tendons from injury of swine that underwent Injury + Repair surgery. * Indicates significant difference (p<0.05, student-t test).
Figure 2:
Figure 2:
Viscoelastic properties of the tendon tissues at lower frequencies. (A) dynamic modulus (E*), (B) storage modulus (E’), (C) loss modulus (E”), and (D) damping ability (Tan δ). Control indicates the group of swine that received normal diet and no surgery. Surgery CS indicates uninjured tendon from contralateral side of swine that underwent either injury or injury + repair surgery. Injury IS indicating tendon from injury side that underwent injury. Injury + Repair IS indicating tendons from injury of swine that underwent Injury + Repair surgery.
Figure 3:
Figure 3:
Viscoelastic properties of the tendon tissues at higher frequencies. (A) dynamic modulus (E*), (B) storage modulus (E’), (C) loss modulus (E”) and (D) damping ability (Tan δ). Control indicates the group of swine that received normal diet and no surgery. Surgery CS indicates uninjured tendon from contralateral side of swine that underwent either injury or injury + repair surgery. Injury IS indicating tendon from injury side that underwent injury. Injury + Repair IS indicating tendons from injury of swine that underwent Injury + Repair surgery.
Figure 4:
Figure 4:
Representative image of tendon histology (H&E). (A) Control, (B) Surgery CS, (C) Injury IS, (D) Injury + Repair IS. Control indicates the group of swine that received normal diet and no surgery. Surgery CS indicates uninjured tendon from contralateral side of swine that underwent either injury or injury + repair surgery. Injury IS indicating tendon from injury side that underwent injury. Injury + Repair IS indicating tendons from injury of swine that underwent Injury + Repair surgery The images were acquired in 20x magnification.
See this image and copyright information in PMC

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