Osteoarthritis (OA) of the hip is one of the leading causes of disability among elderly men and women. This progressive joint disease involves multiple factors, including genes, age, gender, hormones, as well as body mass index, mechanical stress. In addition, a developmental condition known as acetabular dysplasia can contribute to disease risk. Often present at birth, acetabular dysplasia is marked by a shallow hip socket, making the hip unstable and, in extreme cases, prone to dislocation. Severe acetabular dysplasia has been linked to premature hip OA. The influence of moderate acetabular dysplasia on the development of hip OA is less clear. To assess the role of moderate acetabular dysplasia in the onset of hip OA, a research team in the Netherlands conducted a long-term study on 835 women and men ages 55 years and older. Their results, published in the March 2005 issue of Arthritis & Rheumatism (http://www.interscience.wiley.com/journal/arthritis), indicate acetabular dysplasia, even when assessed at a mild degree, as a strong independent risk factor for OA of the hip, even in an elderly population.