Cartilage Defects: Epidemiology and Natural History

In contrast to earlier reports, recent studies clearly document that articular cartilage defects occur rather often but remain unnoticed in many cases. Depending on the lesion size, primary articular cartilage defects eventually increase the risk of osteoarthritis (OA) significantly. OA develops locally and is associated with biomechanical aetiology: in most cases excessive load onto cartilage and aging are among the main factors contributing to OA. This type of OA is sometimes referred to as primary OA. Friction and wear particles, injury, systemic diseases or dysplasia may cause OA prematurely and individuals develop a so-called secondary OA. Evaluation of prevalence and incidence of primary versus secondary OA is difficult, as onset and development of cartilage degradation remain obscure in many cases for a long time. However, published data of latest research suggest significant frequencies of secondary OA, especially in the knee, as a consequence of primary cartilage defects and other injuries of the joint. Therefore, improved techniques of diagnosis are urgently needed in order to inform patients or even treat cartilage defects at early stages before degenerative processes destroy articular cartilage and joint function completely.