Are we evaluating osteonecrosis adequately?

PURPOSE: It is well recognised that to evaluate a patient with osteonecrosis of the femoral head (ONFH) adequately, it is necessary that the size of the infarct and the extent of femoral head joint involvement be indicated, in addition to the type or stage of the pathological process. The purpose of this study was to determine whether patients with ONFH are being evaluated adequately in studies published during the past 25 years and to see if any trends can be identified.

METHODS: Articles describing treatment of patients with ONFH, published between 1985 and 2011, were reviewed to determine the methods used to indicate the type and extent of pathology present on radiographs and magnetic resonance imaging (MRI) studies. The classification systems cited were identified and divided between those which indicated only the stage and those which indicated both stage and extent of involvement.

RESULTS: In 208 studies published between 1985 and 2011, specific classification systems were cited 237 times. During this period, non-quantitative systems, which only indicate stage, were cited 139 times (59 %) and quantitative systems, which indicate both stage and extent of involvement were cited 77 times (32 %). Between 2006 and 2011, non-quantitative systems were cited 30 times (48 %) and quantitative systems were cited 27 times (44 %).

CONCLUSIONS: During the past 25 years there has been a trend towards the use of more comprehensive and effective methods of evaluating patients with ONFH. However, during the past five years, approximately half of the published studies continued to use limited, non-quantitative methods of evaluation. This should be brought to the attention of the orthopaedic community. Future investigations and publications on ONFH should employ comprehensive methods of classification which include not only the stage of disease but also measurements of the size of the necrotic segment and the extent of femoral head and joint involvement.