Major questions regarding cause, cure and prevention of osteoarthrosis have yet to be answered. Presented here is an authoritative collection of well-illustrated anatomical and biochemical studies in both man and animal models that reflect the current state of knowledge about this commonly occurring joint disorder. The focus is on three areas: the nature of processes that mediate joint damage in OA, means of intervention in these processes and the limitations of present methods for assessing joint changes. Taken together, the papers in this volume should facilitate understanding of the natural history of OA and the benefits of intervention, whether in individual patients or in clinical trials.