Introduction: Collagen is the main protein of connective tissue. It has great tensile strength, and it is the main component of ligaments and tendons. It is responsible for skin elasticity, and its degradation leads to wrinkles that accompany aging. Materials and methods: Tissues were scanned in a computer-controlled Perkin-Elmer DSC-7, fitted with an Intracooler, and running software supplied by the manufacturer (1991 revision) was used for the calorimetric measurements. Results and discussion: The high enthalpy of unfolding of collagen is thought to derive mainly from the breaking of the hydrogen bonds between triple helixes and hydrogen bonds forming the hydration network around the collagen molecule. Conclusions: Disc disease induces changes in collagen structure and leads to formation of additional crosslinks between collagen fibers.