A basic study on the mechanical properties of synthetic absorbable sutures under various pH conditions in vitro

Abstract

In veterinary surgery, the choice of suture is determined by the surgeon based on a combination of factors, such as differences in disassembly time, price, and suture site. However, no unified comparison has been made across companies, and the differences are often unclear. In this study, we compared the mechanical properties (maximum tensile load, maximum extension, and maximum twist) of seven synthetic absorbable sutures at baseline (day 0) and over time under different pH conditions (PBS: pH 7.2, acidic: pH 5.6, alkaline: pH 8.8). At baseline, the comparison showed no significant difference in tensile load, but monofilament sutures exhibited a significantly higher extension than multifilament sutures. In terms of twist, the results varied, with significantly higher values for PDS II and MonoSynthe, both of which are polydioxanone based, suggesting that material differences may have influenced the results. On the other hand, multifilament sutures showed lower values over time in all conditions compared to monofilament sutures. Therefore, it was concluded that multifilaments were more strongly affected by solution immersion than monofilaments and lost their mechanical properties earlier. The results also revealed distinct patterns in twist behavior over time, especially MonoSynthe exhibited much lower twist values under alkaline pH compared to other monofilament sutures. These results suggest that twist could be a valuable addition to conventional evaluation methods for suture characteristics. Further multifaceted evaluations will contribute to the development of more comprehensive selection criteria for sutures used in veterinary clinical practice.

Keywords: in vitro; mechanical property; pH condition; synthetic absorbable suture.

Fig. 1.

Setup of the digital force gauge and electric measurement stand. A digital force gauge and an electric measurement stand used for the measurements are shown. Tension load and extension were measured by applying vertical tensile force (A). For twist measurement, a K-wire was inserted at the center of the loop while applying 80% of the maximum tensile load, and the number of rotations until broke was measured and recorded up to the final angle (B).

Fig. 2.

Change over time in the mechanical properties of synthetic absorbable sutures in different pH solutions. Seven synthetic absorbable sutures were immersed in three different pH solutions, and their mechanical properties were measured at different time points. All measurements for the sutures were performed with n=7. The changes over time in the measured values was compared. Data are presented as mean ± SD. Monofilament sutures are represented using warm colors, while multifilament sutures are represented using cool colors.

Fig. 3.

Comparison of the mechanical properties of synthetic absorbable sutures at day 21 in different pH solutions. The mechanical properties of seven synthetic absorbable sutures were measured at day 21. The results were compared between different pH solutions. All measurements for the sutures were performed with n=7. Data are presented as mean ± SD. Asterisks indicate statistical significance at P<0.05.