Anterior cruciate ligament reconstruction using a composite collagenous prosthesis. A biomechanical and histologic study in rabbits.

We evaluated a prototype composite collagenous anterior cruciate ligament replacement device designed to possess the advantages of biological grafts and synthetic materials. Collagenous anterior cruciate ligament prostheses were made by embedding 225 reconstituted type I collagen fibers in a type I collagen matrix, and placing polymethylmethacrylate bone fixation plugs on the ends. The collagenous prosthesis was used to replace the anterior cruciate ligament of 31 mature rabbits. At 4 and 20 weeks postimplantation, histologic and mechanical studies were performed on the developing neoligament tissue, and compared to values for the contralateral sham-operated control. At 4 weeks, neoligament tissue infiltrated the collagen fibers of the prostheses. The tibial bone tunnel attachment site contained new bone approaching the fibrous neoligament. The glutaraldehyde-treated prosthetic fibers appeared intact, while the carbodiimide-treated prosthetic fibers began to resorb. The ultimate load and ultimate tensile strength of femur-neoligament-tibia complexes had decreased. At 20 weeks, glutaraldehyde-treated fibers appeared partially intact; in contrast, the carbodiimide-treated prostheses appeared to be completely degraded, and were replaced by organized, crimped neoligament tissue. The ultimate tensile strength and ultimate load increased substantially due to deposition and remodeling of neoligament tissue. The neoligament ultimate load was 2 to 4 times the initial load value of the prosthesis. Implantation of a resorbable, composite collagenous anterior cruciate ligament prosthesis encourages the development of functional neoligament tissue. Studies are underway to optimize the mechanical and biological properties of the prostheses.