Functional evaluation of polyarylamide fibers for use in a prosthesis for anterior cruciate ligament replacement in the sheep.

In order to evaluate the potential use of polyarylamide fibers as a prosthetic material for ligament replacement, resected sheep anterior cruciate ligaments were replaced by braided devices routed through a tibial tunnel and over the top of the lateral femoral condyle. Twelve sheep were used and sacrificed between 3 and 12 months. The tissue response to the implant was evaluated histologically. Morphologic features of the fibers and the abraded particles were measured by image analysis. Simultaneously, the tensile properties as well as the creep and fatigue properties of non-implanted prostheses were measured under laboratory conditions. It was shown that the polyarylamide fibers exhibited high strength, a high modulus, but low fatigue abrasion properties. At autopsy, 1 prosthesis was broken, 6 had frayed and 5 were intact. There was no adverse tissue response to the intact fibers. Inflammation was always linked to the presence of polymeric particles. A large bony ingrowth in the tibial tunnel through the prostheses strands was observed. There was no material resorption throughout the experiment. Polyarylamide fibers appear to be a suitable material for ligament replacement provided that abrasion against bone can be avoided.