OBJECTIVETo study the biodegradation process of the bioabsorbable mini-plate (LactoSorb) and its influence on bone healing.

METHODS15 mature New Zealand White Rabbits were selected as the experimental animals. The bilateral zygomatic arch were fractured using a fissure bur. One side was fixed with the bioabsorbable mini-plate and the other side was fixed with Titanium mini-plate as a control. 5 animals were killed after 4, 12, and 24 weeks post operation respectively for radiographic and histologic study.

RESULTSAt 4 weeks, the absorbable plate changed from transparent to opaque and its dimensions was enlarged. The bone gaps of both groups were filled with new bone. No inflammatory cells were found in both groups. At 12 weeks, the absorbable plate broke to small pieces or particles, its dimensions reduced greatly but the outline could still been recognized. The bone continuity had been reestablished in both groups. At 24 weeks, the absorbable plate was resorbed completely. Only the residual screw could be seen in the screw hole. Complete bone healing was seen in both groups. No histological differences of bone healing were found at this stage.

CONCLUSIONThe absorbable plate demonstrates excellent biocompatibility. No adverse local inflammatory reactions were found during the plate was absorbed gradually. In the non-weight baring area, the absorbable plate provides the same fixation stability as that of the metal plate.