According to the standard for the biological evaluation of the medical devices, several tests were performed to evaluate the tissue toxic effects induced by
polydioxanone (Group A),
chitosan (Group B), and hydroxyapitite/
collagen (Group C), which were tested as component materials of the chest wall
prosthesis. In the
hemolysis test, 0.2 ml of the
anticoagulant rabbit blood was added to the component materials and the
normal saline (negative control) and to the distilled water (positive control). Five samples were made in each group. Absorbency was measured and the
hemolysis rate was determined. In the acute systemic toxicity test, 20 mice were randomly divided into 4 groups (Groups A, B and C, and the
normal saline group, n=5). The leaching liquid (50 ml/kg) was injected through the caudal vein, which was observed at 24, 48 and 72 hours. In the
pyrogen test, 12 rabbits were randomly divided into 4 groups (Groups A, B, C and the
normal saline group, n=3) the leaching liquid(10 ml/kg) was injected through the ear vein, and the body temperature was recorded within 3 hours. In the in vivo degradable test, the component materials (10 mm x 10 mm) were implanted in 12 rabbits at 2, 4, 8, 12, 16 and 24 weeks, respectively, after operation. Two rabbits were sacrificed for the macroscopic and the microscopic examinations.
RESULTS: The chest wall component materials had no hemolytic reaction, no acute systemic toxicity, and no
pyrogen reaction. The results demonstrated that the implanted materials had only a mild inflammatory reaction during the early days of the grafting, which subsided gradually. There was no tissue denaturation,
necrosis or pathological
hyperplasia when the
prosthesis materials were degraded.
CONCLUSION: The degradable materials of the chest wall
prosthesis have a good biocompatibility and a great biological safety though their surgical application still requires a further clinical research.