Journal of Biomechanics

Daniel K. Moon DK, Woo SL-Y, Takakura Y, Gabriel M, Abramowitch S


Fresh frozen soft tissues are normally used for biomechanics research. However, as experimental protocols for biomechanical evaluation are becoming more complex and time-consuming, specimens may require extra periods of frozen storage before the experiment is completed (Shoemaker and Markolf, 1982). Although one period of frozen storage on ligaments has been shown to have relatively little effect on the biomechanical properties of ligaments (Viidik and Lewin, 1966; Noyes and Grood, 1976; Dorlot et al. 1980; Barad 1982; Nikolaou et al. 1986; Woo et al. 1986) and tendons (Matthews and Ellis 1968; Leitschuh et al. 1996; Clavert et al., 2001), it is unclear if refreezing will significantly affect these properties.

Therefore, the objective of this study was to evaluate the effects of refreezing on ligaments, specifically on the viscoelastic and structural properties of the femur-medial collateral ligament-tibia complex (FMTC), as well as the mechanical properties of the medial collateral ligament (MCL) midsubstance in comparison to fresh specimens. In addition, the preparation used for the refrozen specimen was a regimen designed to mimic the laboratory setting where a frozen/thawed ligament may be completely exposed during dissection and testing before it is refrozen. Since one cycle of freezing and thawing was previously found to affect the area of hysteresis in the previous study (Woo et al. 1986), a more robust viscoelastic analysis was performed in this study.