Currently, animal and clinical research on biomaterials, such as surgical sutures, are mainly performed by removing them from the experiment targets and observing them by microscopy. However, traditional microscopy is not able to observe the internal structure, and there is a risk of sacrificing animals to remove the suture and damaging the materials. Therefore, we introduced optical coherence tomography (OCT) to observe and evaluate four different kinds of surgical sutures in vivo (monofilament absorbable and nonabsorbable sutures and braided absorbable and nonabsorbable sutures). As a result, while the monofilament nonabsorbable sutures showed almost no change over time, the absorbable sutures had color fading and it was also confirmed that the internal structure became chaotic due to decomposition, which improved the OCT signal intensity. For the braided sutures, both absorbable and nonabsorbable, we found that the reflection signal improved from week 0 because blood got among the filaments of sutures and dried during recovery which increased OCT signal from week 0 to week 1. We also confirmed that the braided sutures untwisted over time. All four kinds of sutures were pulled due to the movement of rats during recovery. It is expected that OCT technology will be of great help in in vivo experiments on biomaterials such as sutures.
