Effects of postmortem storage by freezing on ligament tensile behavior

Area of Science:

• Orthopedic biomechanics
• Ligamentous tissue engineering
• Postmortem tissue preservation

Background:

• The medial collateral ligament (MCL) is crucial for knee stability.
• Understanding the effects of tissue preservation is vital for research and clinical applications.
• Freezing is a common method for storing biological tissues, but its impact on ligament properties requires investigation.

Purpose of the Study:

• To evaluate the effects of prolonged postmortem freezing storage on the structural and mechanical properties of the rabbit knee MCL-bone complex.
• To assess changes in the MCL substance's biomechanical characteristics after freezing.

Main Methods:

• Rabbit knee femur-MCL-tibia specimens were subjected to tensile testing.
• Comparison between fresh and frozen (-20°C for 1.5-3 months) samples.
• Analysis of cyclic stress relaxation, load-deformation characteristics, failure properties, and stress-strain curves.

Main Results:

• No statistically significant changes were observed in load, deformation, or energy absorption at failure between fresh and stored samples.
• The area of hysteresis significantly decreased in stored samples during initial cycles.
• Stress-strain curves, tensile strength, and ultimate strain of the MCL substance remained unaffected by freezing.

Conclusions:

• Proper and careful freezing storage has minimal to no adverse effect on the biomechanical properties of the MCL-bone complex.
• The structural integrity and mechanical function of the MCL are well-preserved following prolonged freezing.
• These findings support the use of freezing for preserving ligamentous tissues for biomechanical studies.