Performance of a sterile meniscal allograft in an ovine model

Meniscus transplantation is indicated for persistent pain in a meniscectomized knee. Currently, grafts are prepared aseptically, which provides limited protection against donor-derived infection. The performance of a novel, sterilized meniscus was compared with an aseptically prepared one in an experimental model. Twenty-two sheep were divided into three groups: aseptic meniscal allograft, sterile meniscal allograft, and medial meniscectomy. Animals were euthanized 2 and 4 months after surgery. Meniscal assessments included cell viability, histology, and biomechanical testing. Articular cartilage was evaluated through histology and Outerbridge scoring. Aseptic and sterile allografts had cell viabilities of 59.7% and 58.7%, respectively, at 4 months, which was less than native controls. Grafts had decreased compressive strength at 4 months compared with their preimplantation moduli and were weaker than native menisci. In operated knees, the tibial plateau had more severe degenerative changes, although Outerbridge scores were similar between operated groups. Overall, the allografts were similar in their cellularity and biomechanical properties but were inferior to the native tissue at these end points. The severity of chondral damage in the allograft knees could not be distinguished from meniscectomized joints. The sterilization process does not appear to compromise tissue integrity and provides additional allograft safety.