Figure 1.

Stages of OA after initial trauma. At the molecular level, a joint trauma can set off a series of events immediately beginning with disturbance in joint homeostasis and, over time, leading to end-stage disease. The focus of research is shifting, albeit slowly, from end-stage disease, where total joint replacement is the only solution, to pre-OA stage where early molecular markers can predict the likelihood of clinical disease. At each stage following trauma, a distinct set of biochemical changes occur.