Articular cartilage of the knee is a type of hyaline cartilage that is made of chondrocytes and extracellular matrix. Most of the cartilage, approximately 98% of its volume consists of extracellular matricex, while the remaining 2% is made up of chondrocytes. The extracellular matrix is mainly composed of water, collagen type II and glycosaminoglycans. Cartilage is poor in blood and lymphatic vessels, so it is nourished by diffusion from the synovium, which contributes to its poor regeneration. Cartilage degeneration is considered one of the key risk factors for the development of knee osteoarthritis. Knee cartilage defects are classified according to Outerbridge and ICRS (International Cartilage Repair Society). Treatment can primarily be divided into conservative and surgical methods. Conservative methods are used as the first method of treatment before some larger, more invasive techniques. Surgical methods can be divided into symptomatic, reparative and restorative. Symptomatic methods are used to reduce pain and improve joint function. These methods include techniques such as debridement and intra-articular joint lavage. Reparation methods are based on the use of mesenchymal cells that are released into the cartilage with the aim of its recovery. These include techniques such as microfracture, subchondral abrasion and MACI (matrix-induced autologous chondrocyte implantation). The goal of restoration methods is to complete the cartilage defect with the same cartilage due to its properties such as resistance to mechanical stress. Grafts, implants, stem cells, gene therapy and many others are promising in the restoration of articular cartilage of the knee, but further and due studies are needed to confirm their usefulness and consistency, but also their disadvantages. There is still no universal therapy for injuries to the articular cartilage of the knee. Furthermore, the treatment is based on the wishes, lifestyle of the patient and also on the previous experience of the orthopaedic surgeon.