Dude, Where's My Stitch? Strength Analysis of Absorbable Sutures via COMSOL
Dong, Owen; Kaufman, Jonathan; Kumar, Supriya; Mari, Liana
A common method in aiding postoperative tissue healing is the use of a suture, which functions by holding tissues together. The ideal suture is able to lose strength at the same rate that the tissue gains strength. Absorbable sutures have been studied to provide that strength for the tissue, while at the same time reducing tissue trauma caused by the gradual absorption of the biocompatible material. Because of its excellent fiber-forming ability and biodegradability, polyglycolic acid (PGA) has been investigated for developing resorbable sutures . A computational model of the decomposition and mechanical analysis of this suture provided insight into how the mechanical strength of the suture changes as it deteriorates. In this novel study, we aimed to create a model via COMSOL that would simulate the degradation of a dissolvable suture and analyze the sutures changing mechanical properties during degradation. Diffusion of water into the suture occurs so quickly that we realized that bulk erosion, not surface erosion, was the main means of degradation. We created a model that simulated the effect of the natural decomposition of the PGA suture within the body via bulk erosion. By decreasing the volume and applying a uniaxial load to the model, we related the effective Young’s modulus to the original Young’s modulus of the material as the suture degraded. Suture decomposition rate was determined from scientific literature and previous experiments. The suture’s effective elastic modulus decayed with time as the suture dissolved and was absorbed by the body. Knowing the rate at which the elastic modulus decays will allow us to predict the point in time at which the suture no longer holds the tissues together. Findings on the change of material properties of the suture over time are a valuable first step for determining the initial elastic modulus of sutures required for certain tissue repair.