DescriptionThe knee joint is the largest and most complex joint in the human body. Its stability is largely dependent on the anterior cruciate ligament (ACL), a dense fibrous connective tissue that attaches the femur to the tibia. Under high tensile and torsional forces the ACL will tear and does not heal without surgical intervention. This is due to the low blood supply and ligament retraction from the synovial tissue that envelops a tear. We explored the potential of a novel ACL reconstructive device composed of a hybrid poly(desaminotyrosyl-tyrosine dodecyl dodecanedioate)(12,10) [p(DTD DD)] and type I bovine collagen fiber scaffold as an alternative to current autograft and allografts techniques. The three phase process initially tested the fabrication and characterization of p(DTD DD) fibers and compared them to poly(L-lactic acid) (PLLA), a common biomaterial. Data suggested that p(DTD DD) fibers, with their higher strength, lower stiffness, favorable degradation products and comparable cell compatibility, may be a superior alternative to PLLA fibers for development of an ACL reconstructive device. The second phase tested electron beam (E-beam) sterilized hybrid scaffolds composed of parallel 75% p(DTD DD) and 25% collagen fibers. Hybrid scaffolds were implanted for up to 4 weeks in the ACL space of New Zealand White (NZW) rabbits. At 4 weeks there was far more cell infiltration, vascular tissue and granuloma. Inflammatory cells were concentrated on the outer part of the scaffold, which is the natural repair reaction to surgery and not the implant. The third phase used a similar scaffold in a braided configuration, a larger sheep model and a longer 12 week time point. Analysis showed an increase in the amount of cellular infiltration and vascular tissue after 12 weeks. There was a decrease in the amount of eosinophils and no change in the number of multi nucleated giant cells after 12 weeks. Cellular infiltration was apparent at the center of the scaffold, which suggests that spacing between fibers is large enough to allow cells to migrate freely throughout the scaffold. Data suggests there is a definite potential in using a braided hybrid fiber scaffold composed of p(DTD DD) and Collagen as an ACL reconstructive device.