In Vivo Time-Lapse Observation of PLA/CL and PVDF Surgical Sutures by Optical Coherence Tomography

Abstract

We applied Optical Coherence Tomography (OCT), which has the advantages of high speed and high resolution on imaging, to perform in vivo animal experiments on surgical sutures. A Spectral-Domain OCT system was used to scan the absorbable PLA/CL surgical sutures and Non-absorbable PVDF surgical sutures, both of which had been sutured on a hairless rat. Two kinds of surgical sutures, polylactic acid/ polycaprolactone (PLA/CL) compound surgical sutures, which is absorbable, and polyvinylidene fluoride (PVDF), which is non-absorbable, have been sutured on the back of a hairless rat. And a Spectral-Domain OCT was used to take the pictures of both surgical sutures and surrounding tissues every week till PLA/ CL sutures was absorbed and broken in order to record and analyzed the changings. As a result, the deposits on the surface of the suture that were observed over time were decomposed substances of keratinocytes and fibers. Furthermore, with the decomposition, the crystal structure of PLA/CL fiber became amorphous, and reflected signal was detected. Some void also appeared which shows that the proliferated part detached from the sutures and the epidermal layer. PLA/CL sutures finally got broken at the 16th week, with the diameter decreased from 220 μm to 180 μm. In vivo time-lapse observation of surgical sutures can be accurately performed by OCT. It is also able to scan not only the surface but also the internals structure like crystal changes of surgical sutures. What's more, with 40 μm decrease on diameter, PLA/CL sutures broke after 15 weeks.