Older adults with a developmental abnormality of the hip socket that makes the joint unstable are more than four times more likely than unaffected people to develop Osteoarthritis of the hip, Dutch researchers report.

There is evidence that acetabular dysplasia, as the hip socket abnormality is called, is related to Osteoarthritis, but there have been few forward-looking studies investigating this association, say Dr. M. Reijman and colleagues at Erasmus Medical Center in Rotterdam.

To investigate further, the researchers followed 835 men and women 55 years of age or older for an average of 6-1/2 years.

At an average of 65-1/2 years of age, 9.3 percent of the subjects developed hip osteoarthritis, defined as a decrease in joint space width of 1 millimeter or more, the team reports in the March issue of Arthritis and Rheumatism

Subjects with the unstable hip condition had a 4.3-times greater risk of hip osteoarthritis than those without the condition. This was independent of other known risk factors such as age, sex and body mass index.

However, the association tended to be enhanced by being female, being involved in heavily demanding physical work and having a low BMI.

In a statement, Dr. Reijman said that these figures may underestimate extent of the problem. “We assume that in a younger population the association between acetabular dysplasia and osteoarthritis may be even higher.”

SOURCE: Arthritis and Rheumatism, March 2005.