Medical grade honey (MGH) has been shown to have invaluable antimicrobial properties, particularly in the current state of antimicrobial resistance. A Belgian study looked at the effects of MGH on the tensile properties of three synthetic absorbable suture materials [Madsen, K.; Martens, A.; Haspeslagh, M. et al. The effect of medical-grade honey on tensile strength, strain, and Young’s modulus of synthetic absorbable suture material used in equine surgery. Equine Veterinary Journal May 2023; DOI: 10.1111/evj.13966].
Tensile strength describes the measure of suture under load until it breaks. Surgeons would understandably want to have confidence that sutures will hold without early breakdown that could lead to wound dehiscence, hernia formation or other catastrophic consequences.
In this study, three suture materials were examined in vitro relative to the effects of honey on them: polydioxanone (PD, PDX); polyglycan (PG, Sacryl); and poliglecaprone (PC, Monfast). Each strand of suture material was given a single throw in the middle of the thread. The suture materials were incubated in a) MGH; b) phosphate buffered saline (PBS, ph7.4); c) equine plasma (EP); and d) a combination of MGH and equine plasma (HP). Incubation of 10 strands of each material was performed 1, 7, 14, 21 and 28 days following centrifugation within a tube to completely immerse each suture in the material. Each material was also tested directly from the packet and in a dry environment. All samples also were tested for microbial growth at the time of mechanical testing.
Effects of MGH on Tensile Strength
While polydioxanone (PD) degrades more quickly in an acidic environment, and honey tends to create pH 3.2 – 6.1, after 28 days of incubation in MGH, PD preserved its tensile strength comparable to the out-of-package sample.
Polyglactin (PG) and poliglecaprone (PC) typically degrade more quickly in alkaline environments. After 28 days, PG incubated in MGH showed similar tensile strength to the dry out-of-packet material. Similarly, PG incubated in the combination of MGH and equine plasma had higher tensile strength compared to incubation in PBS and EP. The faster degrading suture is PC, which only retains 25% of its tensile strength after two weeks and complete loss by 28 days. In this study, PC incubated in PBS and EP had a nearly complete loss of tensile strength by 21 and 28 days. However, when incubated in MGH, PC retained some measurable tensile strength after 28 days.
Because degradation of these three types of sutures depends on hydrolysis, it is possible that honey has low water availability and subsequently slower loss of strength. In this study, however, no loads or multi-directional forces were placed on the sutures, and there was no investigation into knot strength when exposed to various media. In addition, blood and wound secretions normally seen in a wound were not present to dilute the effects of MGH.
The authors summarized: “MGH did not accelerate the degradation of the suture materials. Even in the mixed medium containing MGH and equine plasma, reflecting a more realistic image of the in vivo environment, the sutures seem to retain a higher or equal breaking strength compared to media without MGH. Therefore, it can be concluded that MGH can safely be applied as a preventive antiseptic measure in surgical wounds without the risk of premature loss of tensile strength.”