Effect of Biological Environment on Polyester Surgical Suture's Physical Properties: An Experimental Study in Rats

Objective The following study aims to analyze the alteration of nonabsorbable polyester surgical suture physical properties after in vivo incubation. Methods A comparative study of braided nonabsorbable polyester 2/0 (U.S.P) sutures was performed. The control in vitro group and three experimental in vivo subgroups, composed of ten sutures in each, were created. All 30 experimental sutures were implanted into a total of 15 laboratory rats subcutaneous tissue (two sutures in each rat) and removed after seven, eight and nine weeks, respectively. Further, they were attached to the mechanical testing device and affected with a mechanical force, increasing the load by 0,1 N/s until complete breakage. Tensile strength (TS), failure displacement (FD), failure strain (FS) and failure stress (FST) were measured at the point of failure and compared to the same parameters of the control group. Results No statistically significant difference was found in the physical parameters of the samples between the experimental and control groups (TS [p = 0.358], FD [p = 0.258], FS [p = 0.258] FST [p = 0.358]). A statistically significant difference was found in the failure load between sutures that break on the knot site (KS) and the rest of the samples: significantly less force was needed to break the suture on the KS. Moreover, most of the breaks on the KS occurred in sutures that were incubated for the longest period of nine weeks (n = 4). An anomaly of partial failure (PF) was noticed. Sutures with PF elongated significantly more compared to the sutures that did not undergo PF in the control and in experimental groups (p = 0,044; p = 0,017; p = 0,016; p = 0,013). Conclusion The biological environment had no radical aftereffects to the suture's physical properties. In vivo exposure may cause the suture to break on the KS more frequently and may lead to PF, when a few sutures composed of fiber fail. Sutures that undergo PF tend to elongate further.