Abstract
Aims: This work analyzed the effects of storage by fresh-freezing at −80°C on the histological, structural and biomechanical properties of the human posterior tibial tendon (PTT), used for ACL reconstruction.
Methods: Twenty-two PTTs were harvested from eleven donors. For each donor one tendon was frozen at −80°C and thawed in physiologic solution at 37°C, and the other was tested without freezing (control). Transmission electron microscopy (TEM), differential scanning calorimetry (DSC) and biomechanical analysis were performed.
Results: We found the following mean changes in frozen-thawed tendons compared to controls: TEM showed an increase in the mean diameter of collagen fibrils and in fibril non-occupation mean ratio, while the mean number of fibrils decreased; DSC showed a decrease in mean denaturation temperature and denaturation enthalpy. Biomechanical analysis showed a decrease in ultimate load and ultimate stress, an increase in stiffness and a decrease in ultimate strain of tendons.
Conclusions: Fresh-freezing brings about significant changes in the biomechanical and structural properties of the human PTT. A high variability exists in the biophysical properties of tendons among individuals and in the effects of storage on tendons. Particular care is required when choosing an allograft tendon and further studies are required to clarify the role of donors’ age and sex, and other factors, in determining the suitability of an allogenic tendon. The future directions could be:
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(a) To choose the tendon grafts considering the donors’ characters;
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(b) To use fresh tendons;
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(c) To test the controlateral tendon from the same donor before use.
The abstracts were prepared by incoming Professor Elena Brach del Prever. Correspondence should be addressed to IORS – President office, Dipartimento di Traumatologia, Ortopedia e Mediciana del Lavoro, Centro Traumatologico Ortopedico - Via Zuretti, 29 I-10135 Torino, Italy.
