BONE REMODELING AFTER INTERNAL-FIXATION WITH DIFFERENT STIFFNESS PLATES - ULTRASTRUCTURAL INVESTIGATION

Forty adult New Zealand rabbits were used in this experiment. Four rab bits served as control and the rest 36 being divided into 3 groups, ea ch of which was fixed respectively with methylmethacrylate, titanium a lloy and stainless steel plate on the left intact tibiae. The cortical bone beneath the plate was harvested at 2, 4, 8 and 12 weeks after op eration and observed by means of using transmission electron microscop e. The major ultrastructural changes after internal fixation with diff erent stiffness plates were alteration of osteocyte life cycle, perila cunar matrix and disorder of osteoblast and osteoblast coupling. The g reater the stiffness of the plate, the greater the ultrastructural cha nge.