[Reconstruction of the orbits with polylactate implants: animal experimental results after 12 months and clinical...

In earlier experiments healing of large orbital wall defects in sheep occurred undisturbed by osteoconductive bone growth along biodegradable membranes when there was no interference with additional bone grafts or titanium miniplate osteosynthesis. In this experiment similar bilateral defects were reconstructed with poly(L/DL 80/20) lactide implants using a microporous membrane 0.5 mm thick without further support on one side, an 0.25 mm microporous membrane supported by solid polylactide buttresses and stabilized by polylactide dowels on the opposite side. After 12 months we found a symmetrical reconstruction of the normal anatomy of the orbits in CT and X-ray examinations. In contrast, histologic investigations revealed massive foreign-body reactions around degrading buttress implants and dowels especially. Milder reactions occurred in some orbits along the membranes as well, in contrast to our earlier experiments with 4-month follow-up. None of the implants had degraded completely 12 months after surgery. In our 12-month long-term survey, polylactide microporous membranes confirmed their osteoconductive potential in orbital wall reconstruction. Nevertheless, massive polylactic implants should not be considered for clinical application in the orbit because of significant late foreign-body reactions.