Quantification method to objectively evaluate the fibrous structural status of tendons based on polarization-sensitive OCT

Histological analysis is widely used to evaluate injured tendons; however, it has the limitation of being semi-quantitative. Hence, we developed a quantification method to objectively evaluate the fibrous structure of tendons, exhibiting the optical property of birefringence, using polarization-sensitive optical coherence tomography (PS-OCT). We used a partial-rupture rat model in which the middle 0.75 cm of the Achilles tendon was cut with a blade. Rats were sacrificed at 2, 4 or 6 weeks after the injury, and PS-OCT and histological analyzes were performed. The PS-OCT phase retardation images and score well represented the structural changes of the injured tendon according to the wound healing state. Therefore, the proposed novel quantification method using PS-OCT can be used to evaluate the fibrous structural status of tendons.