Large Osteochondral Allografts of the Knee: Surgical Technique and Indications

Articular cartilage lesions of the knee are common in active and young population.1 Curl et al2 reviewed more than 30,000 patients treated with knee arthroscopy, reporting chondral lesions in 63% of cases. Arøen et al,3 in a group of approximately a thousand patients undergoing knee arthroscopy with a mean age of 35 years, found a full-thickness cartilage lesion suitable for cartilage repair in 11% of cases. Several studies reported Outerbridge grade III and IV lesions in 5 to 20% of all patients undergoing knee arthroscopy, with 4 to 5% of these patients being younger than 40 years.2–4 Different techniques can be used to repair osteochondral lesions of the knee, and these can be categorized into four group: bone marrow stimulation procedures, osteochondral scaffold, cell therapies, and osteochondral grafting. Debridement and microfractures with bone marrow stimulation are suitable options for lesions smaller than 2 cm without subchondral bone damage.5–7 These procedures result in fibrocartilage repair tissue; this tissue has poor biomechanical properties compared with hyaline cartilage, degenerates faster, and is generally thinner.8–10 Autologous mosaicplasty has the potential to restore small osteochondral lesions but is not indicated in large lesions (>2.5 cm) due to significant donor-site morbidity and the technical difficulties in restoring curved surfaces and uncontained defects.11–14 Autologous chondrocytes implantation provides surface coverage with hyaline-like repair tissue, but it is costly, entails two surgical procedures, and does not restore associated bone defects unless bone grafting is performed.15 Cell-free scaffolds and the use of growth factors are promising new technologies but require additional