Abstract
Understanding the biomechanics of tendon entheses is fundamental for surgical repair and tissue engineering but also relevant in biomimetics and paleontology. Examinations into the 3D tissue deformation under load are an important element in this process. However, entheses are difficult objects for micro-computed tomography due to extreme differences in X–ray attenuation. In this article, the ex vivo examination of Achilles tendon entheses from mice using a combination of tensile tests and synchrotron radiation-based micro-computed tomography is reported. Strains and volume changes are compared between the more proximal free tendon and the distal tendon that wraps around the Tuber calcanei. Tomographic data sets of relaxed and deformed entheses are recorded with propagation-based phase contrast. The tissue structure is rendered in sufficient detail to enable manual tracking of patterns along the tendon, as well as digital volume correlation in a suitable pair of tomographic data sets. The strains are higher in the distal than in the proximal tendon. These results support the existence of a compliant zone near the insertion. Necessary steps to extend the automatic tracking of tissue displacements to all stages of the deformation experiment are discussed.
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