Degradação In Vitro de Implante Biorreabsorvível em Poli (L-Lactide) para Artrodese de Coluna Lombar

Objective: This study traces the degradation profile of a spinal implant produced in PLLA by industrial processes and compares it with results obtained from experiments made in laboratory models. Materials and Methods: A bioabsorbable interbody spinal implant was developed and produced by an industrial injection process. The specimens were degraded in vitro by one year, with the evolution monitored by tests of mass loss and water absortion, gel permeation chromatography, diferential scaning calorimetry, mechanical compression tests and electron scanning microscopy. Results: The degradation in one year was insignificant, without changes in mass, volume or mechanical behaviour. The different tests showed a minimal water absortion by the specimens, without bulk hydrolysis, but only loss of the small polymer chains of the surface and a major rise in cristalinity, probably by an aging process. Conclusions: The implant performed very differently from the small laboratory pieces, with insignificant degradation. It is possible to anticipate that, in clinical settings, it could originate long lasting crystalline residues.