Biodegradable wound-closing devices for gastrointestinal interventions: Degradation performance of the magnesium tip

The aim of this study was to investigate the degradation performance of the magnesium tip of a biodegradable rivet intended for tissue joining and fixing via endoscopic surgery. The in vitro degradation performance was assessed by immersion tests in simulated gastric fluid. The influence of the chemical composition of the alloy, salt concentration, temperature and pH value was investigated. Among the parameters varied, the pH value exhibits the most significant influence on the degradation performance. It represents a potentially useful tool for controlling the tip degradation, allowing the greatest amount of flexibility during the surgical intervention. The biodegradable Mg alloy WZ21 is shown to be a suitable material for the short-term component (the tip) of the rivet. It allows precise tip fabrication with adequate sharpness and degrades homogeneously and sufficiently fast in simulated gastric fluid at low pH values. Due to a suitable surface-to-volume ratio and its rotationally symmetrical geometry, the Trocar tip design is considered the most promising tip shape among the various designs investigated. The results of this study confirm the feasibility of this new concept of completely degradable wound-closing devices and provide a solid basis for further product development.