Mechanical properties of tendons: changes with sterilization and preservation

Area of Science:

• Biomaterials Science
• Orthopedic Surgery
• Tissue Engineering

Background:

• Tendon allografts are crucial for anterior cruciate ligament (ACL) reconstruction.
• Sterilization and preservation methods may compromise the mechanical integrity of allograft tissues.
• Understanding these effects is vital for ensuring graft efficacy and patient outcomes.

Purpose of the Study:

• To evaluate the impact of various sterilization and preservation techniques on the tensile mechanical properties of porcine toe extensor tendons.
• To determine the optimal sterilization method for maintaining tendon allograft quality for ACL replacement.

Main Methods:

• Porcine toe extensor tendons were subjected to different treatments: freezing, freeze-drying, freezing followed by irradiation (25 kGy), freeze-drying followed by irradiation, and freeze-drying followed by ethylene oxide gas sterilization.
• Tensile mechanical properties, including Young's modulus and ultimate tensile stress (UTS), were measured using a dynamic testing machine.

Main Results:

• Freezing alone resulted in a slight but significant decrease in Young's modulus compared to fresh tendons.
• Freeze-drying followed by irradiation drastically reduced the ultimate tensile stress (UTS) by approximately 90% compared to fresh and frozen-irradiated tendons.
• No significant changes in UTS or Young's modulus were observed between fresh, frozen, and frozen-irradiated groups, or between freeze-dried and freeze-dried ethylene oxide sterilized groups.

Conclusions:

• Irradiation sterilization of tendon allografts for ACL reconstruction should be performed after freeze-drying to preserve mechanical properties.
• Freeze-drying followed by irradiation significantly compromises the tensile strength of tendon allografts.
• Careful selection of sterilization and preservation techniques is essential for maintaining the functional capacity of tendon allografts.