| Abstract: | Bioabsorbable materials for use in a clinical situation are required to have specific mechanical characteristics and predictable degradation. We have been studying the mechanical properties and the bioabsorbability of polyesters of aliphatic α-hydroxyacids, such as polylactide, polyglycolide (PGA) and their copolymers, to applying them for surgery, and classifying the effects of the factors governing their biodegradation behavior. Poly-L-lactide (P-L-LA) showed slow degradation and maintained initial mechanical properties for a period of more than 3 months after implantation. In contrast, PGA showed rapid degradation and after its absorption at the site of implantation, good replacement of the tissue was observed. On th basis of these results, various clinical applications for thoracic surgery were evaluated as follows: 1) For the fixation of fractured ribs, pins made from either P-L-LA or a composite of P-L-LA and hydroxyapatite were prepared. 2) For reconstruction of the chest wall, Tricot-Knit PGA mesh and P-L-LA mesh were fabricated. In vivo tests in dogs were then carried out. P-L-LA pins maintained the strength required for connecting the fractured ribs until complete reunion was achieved, while the meshes acted as scaffolding for reconstruction of the connective tissue. In both cases, these materials showed minimal tissue reaction and sufficient biocompatibility. |
