The response of articular cartilage to mechanical injury

Abstract

The type of response of articular cartilage to trauma remains controversial, despite multiple experimental studies. This is based partly on the fact that cartilage responds to different types of trauma in different ways, and partly on confusions in terminology, which may make understanding the healing process diffi cult. For example, do hyaline cartilage injuries heal with true hyaline cartilage, altered hyaline cartilage, or fi brocartilage? The process of articular cartilage healing is clinically relevant due to the huge recent enthusiasm in treating some cartilaginous lesions using arthroscopic surgical techniques such as shaving the irregular, roughened surface of the patella or femoral condyle in those with "chondromalacia". This enthusiasm of clinicians has led to the suggestion that such debridement surgery causes healing of superfi cial defects. However it is possible that other aspects of the surgical procedure, such as synovial changes in response to joint fl uid lavage, that have little or no effect on the cartilaginous surfaces, may account for improvement in clinical symptoms. Nevertheless, the process of cartilage healing remains relevant to joint biology and to our understanding of cartilage metabolism. Before considering the response of articular cartilage to mechanical trauma, one must consider two issues: fi rstly, can adult articular cartilage increase its DNA and matrix synthesis in response to appropriate stimuli? Secondly, what is the normal healing response of body tissues to trauma and what variations of this exist.