COMPARATIVE ANIMAL STUDY OF 3 LIGAMENT PROSTHESES FOR THE REPLACEMENTOF THE ANTERIOR CRUCIATE AND MEDIAL COLLATERAL LIGAMENT

Three different ligament prostheses (Leeds-Keio(R), Gore-Tex(R) and a prototype of Aramid(R)) were implanted in sheep knee joints replacing the anterior cruciate ligament and the medial collateral ligament. Aft er 1 yr the knees were explanted and their biomechanical properties we re assessed by a drawer test and tensile tests of the implants. Additi onally the ligament replacements, the synovial membrane and the lymph nodes were inspected histologically. For each type of prosthesis parti al or total ruptures occurred. None of the operated joints regained no rmal stability and stiffness. Anterior knee stability was best for the Gore-Tex treated group and worst for those joints that received a Lee ds-Keio implant. The stiffness and rupture strength were highest for t he Gore-Tex prostheses. Histologically the strongest intra-articular i nflammatory response was observed in the Gore-Tex treated joints. Insi de the drill tunnels the severest foreign body reaction was found for the Aramid prostheses. Gore-Tex fibres often showed good bony integrat ion. Wear particles formed from all prostheses and caused small granul omas and mild synovities. The results suggest that none of the tested materials represent an ideal solution for ligament replacement. Relati vely good stability does not guarantee good biocompatibility and vice versa. This suggests that ligament prostheses should be applied only i n salvage cases.