RESORBABLE DEVICE FOR FRACTURE FIXATION - IN-VIVO DEGRADATION AND MECHANICAL-BEHAVIOR

The availability of a high molecular weight poly(L-lactide), with supp osed good mechanical properties, encouraged us to carry out an in vivo experimental study to evaluate the degradation rate and accompanying loss of strength during interaction with bone. Small cylindrical PLLA rods were manufactured by compression moulding. Thirty-six male New Ze aland rabbits (b.w. 3 kg), randomly divided into six groups of six ani mals each, were submitted to implantation of the rods under general an aesthesia (O 3x7 mm rods in the lateral condylic region of the right f emur and O 3x50 mm rods in the intracondylic channel of the left femur ). The animals were then sacrificed at the end of each experimental ti me (4, 8, 12, 24, 52, 64 weeks), hence the femurs were explanted. Hist ology showed no inflammatory cells with fragmentation or resorption of bone trabeculae. Mechanical studies showed a decrease in mechanical p roperties and flexional stiffness, and the absence of evident material resorption. Finally, the properties of this newly developed resorbabl e device, when confirmed, seem to justify future clinical introduction of this synthetic material.