The hydrolytic degradation of polydioxanone (PDSII) sutures. Part I: Morphological aspects

The morphological changes in polydioxanone sutures (PDSII), and the resulting changes in properties are explored as a function of in vitro degradation time with the use of small- and wide-angle x-ray scattering, optical microscopy, differential scanning calorimetry, dynamic mechanical thermal analysis, and measurements of tensile properties and mass change. There are significant changes to the properties of the suture on initial hydration. In the time range of 0-80 days investigated, two subsequent stages of degradation are apparent. Chain scission is thought to occur in the first stage, beginning as soon as the chains become hydrated. However, in this stage, the effects of scission on the physical properties of the suture are not apparent. The transition from the first (dormant) stage to the second (active) stage, in which changes to the physical structure and mechanical properties of the fiber become measurable, is gradual, with the first change occurring after about 15 days. The relationships between the changes in the microstructure and the properties are discussed and a general model for the degradation process proposed.