Large fresh osteochondral allografts of the knee: a systematic clinical and basic science review of the literature

PURPOSE: The aim of this study was to conduct an updated review of the literature regarding the clinical and basic science knowledge on osteochondral allograft transplantation in the knee for the treatment of large defects.METHODS: According to specific criteria, 2 investigators systematically reviewed the literature for clinical and basic science reports regarding osteochondral allograft transplantation; data were independently extracted, pooled, and analyzed. Clinical and functional outcomes, International Knee Documentation Committee and Western Ontario and McMaster Universities Osteoarthritis Index scores, return to sport, quality of life, and survivorship of the grafts were assessed from the clinical articles. Regarding the basic science articles, the effects of allograft storage time, temperature, and different storage media were assessed.RESULTS: Eleven articles reporting on clinical data and 14 articles reporting on basic science data (animal, cell, and biomechanical studies) were selected. The articles included in the review were not homogeneous, and different outcome measures were adopted. Overall excellent results were achieved, with improvement in all objective and subjective clinical scores, a high rate of return to sport, and a survivorship rate of 89% at 5 years. When multiple plugs were implanted, posterior grafts seemed to fail. Only 1 article compared fresh versus frozen grafts, with a greater improvement in scores in the frozen group. Cellular viability and number were reduced during storage, even at low temperatures; polyphenol from green tea and arbutin and higher temperatures favorably influenced cell viability of the cartilage during storage. On the other hand, the structural properties of the extracellular matrix were not influenced by the storage at low temperatures. Integration of the graft to the host was also important, and bony integration was usually achieved; however, on the cartilage side, integration was scant or did not occur, especially in the frozen grafts.CONCLUSIONS: Fresh osteochondral allografts of the knee showed good clinical and functional outcomes even at longer-term follow-up. No other effective treatment exists, at the moment, for large osteochondral lesions. This surgical procedure is burdened by cost and difficulty in finding matching fresh donors. A new method to establish chondrocyte viability before the implantation of a new allograft would be a useful decision-making instrument.LEVEL OF EVIDENCE: Level IV, systematic review of Level IV studies