Tensile Strength of Absorbable Suture Materials: In Vitro Analysis of the Effects of pH and Bacteria

OBJECTIVE: To evaluate the tensile strength and suture degradation of 5 commonly used absorbable Suture materials in different pH and bacteria inoculated media. DESIGN: In vitro study of the tensile strength as well as the effect of pH and bacteria on suture degradation for 5 common absorbable suture materials. SETTING: Surgical and Orthopaedics Research Laboratories in Prince of Wales Hospital, New South Wales (Tertiary Hospital/University of New South Wales, Australia). PARTICIPANTS: Chromic catgut, Vicryl, Caprosyn, Bio-Syn, and Maxon were immersed in sterile urine (control), Escherichia coli (E coli) medium, Proteus mirabilis medium (basic medium with pH of 7.8), and acidic medium with pH 5.6. The tensile strength and suture stability were analyzed after immersion in these media after 1, 7, 14, and 28 days. Three runs of test were performed using the universal tensile strength analyzer Mini Bionix (MTS Systems, Eden Prairie, Minnesota), and statistical tests were performed on these results. RESULTS: A decrease in suture tensile strength was noted in all 5 sutures with the Maxon suture showing the least deterioration followed by the Vicryl suture. A I-way analysis of variance test revealed a statistically significant decrease in suture tensile strength over the days of testing, and a post hoc Tukey test confirmed a significant decrease up to day 7 (p < 0.01). The presence of E coli and higher urine pH lead to greater suture degradation, but these were not statistically significant. Linear regression model univariate analysis showed that time contributed to the most significant decrease in tensile strength followed by the types of suture materials tested. The types of media tested were not a significant predictor of tensile strength by itself. CONCLUSIONS: The Maxon suture showed greater suture tensile strength when compared with other sutures. The presence of pH and bacteria caused variable rates of suture degradation, but the result was not significant. (J Surg 66: 208-211. (C) 2009 Association of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.)