Articular cartilage defects in the knee--basics, therapies and results.

Full-thickness defects of the articular cartilage in the knee joint have lower regenerative properties than chondral lesions of the ankle. In order to avoid early osteoarthritis, symptomatic articular cartilage defects in younger patients should undergo biological reconstruction as soon as possible. Various surgical procedures are available to biologically resurface the articular joint line. Numerous animal experiments and clinical studies have shown that early biological reconstruction of circumscribed cartilage defects in the knee is superior to conservative or delayed surgical treatment. This superiority refers not only to defect healing but also to the elimination of changes following secondary osteoarthritis. The various surgical procedures can be differentiated by the range of indications and the final outcome. Additional malalignment, meniscus tears and/or ligament instabilities should be treated simultaneously with the cartilage resurfacing. The mid- and long-term results of the various current techniques are promising, but further modifications and improvements are needed.