Classification systems for osteonecrosis: an overview.

Currently a number of classification systems for osteonecrosis are in use. The use of different systems often leads to confusion and makes it difficult to compare the results of different methods of treatment. Because the management of osteonecrosis is determined in large part by the stage of the disease, it is important to use an effective and reliable method of staging and classification. This article provides an overview of the systems most commonly used so the reader can better understand and compare the outcome of studies that report their results using different methods of classification. The essential features of the ideal system are outlined to enable the reader to decide which of the available classification systems best meets these goals.