Osteochondral Transplantation and Mosaicplasty

The treatment of knee osteochondral injuries remains a controversial issue. The main problem is the limited capacity for chondral injuries to repair. Most chondral lesions are superficial and small, and they respond to conservative treatment. There are two types of chondral lesions in the knee: osteochondritis dissecans and chondral lesions in which the cartilage structure has been damaged to such an extent that it can only be treated with palliative, reparative or restorative measures (autologous or allograft osteochondral grafting and autologous chondrocyte implantation). Mosaicplasty was introduced in order to return to the knee its native cartilage in those lesions in which the only option at that moment was obtaining a fibrocartilage, with poor biomechanical behavior. Mosaicplasty would be primarily indicated for small lesions, 1–2.5 cm2 in diameter without subchondral bone loss, and being the alternative to microfracture or in cases in which bone marrow stimulation techniques have failed. It is a demanding surgical technique. Osteochondral allograft transplantation is a technique not as widespread and indicated as mosaicplasty. Its main indication is in the treatment of a large or complex lesion defined by: size greater than 2.5 cm2, some loss of subchondral bone, multifocal or bipolar character, and an unsuccessful earlier repair procedure. The most recent works are those that show that an increase in storage time of the allografts at 4 °C, up to 28 days after extraction, maintains its effectiveness with high percentage of cell viability.