New techniques for cartilage repair of the patella

Hyaline cartilage has long been recognized as having a limited capability to heal due to the fact that it is avascular, because of the presence of few specialized cells with a low mitotic activity and because of the lack of undifferentiated cells that can promote tissue repair. Once injured, cartilage gradually degenerates owing to both mechanical and biochemical factors leading to osteoarthritis (OA), thereby mandating surgical intervention to achieve repair and to avoid subsequent cartilage degeneration. Chondral or osteochondral cartilage lesions are frequently found during knee arthroscopy. Furthermore, patellofemoral maltracking and instability often acts as an undiagnosed background factor for articular cartilage lesions in the patella and trochlea. The idea of "biological solutions for biological problems" has led to the development of less invasive procedures that in general reduce morbidity while enhancing functional recovery. Autologous chondrocyte implantation (ACI) represents a viable technique for cartilage full-thickness chondral lesion repair. However, essentially it remains a two-step procedure including an arthroscopic biopsy and subsequent implantation of the cultured chondrocytes. Apart from donor site morbidity, the risks of two surgical procedures, and the limited quantity of cartilage that could be harvested, the total cost of surgeries, scaffold, and in vitro culture still represent the major limitation of this technique. A one-step surgical procedure is the order of the day. In this regard, the use of bone marrow aspirate concentrate (BMAC) cells, which contains multipotent mesenchymal stem cells (MSCs) and growth factors, can represent a possible alternative to regenerate cartilage tissue, with encouraging results.