IOWA CITY, Iowa--A recent University of Iowa Health Care study is calling into question the reliability of a classification system that orthopaedic surgeons use to help them evaluate treatment outcomes in children with a hip condition known as Legg-Calve-Perthes Disease.

The system, developed in 1981, is called the Stulberg Classification System. The classification scheme predicts how a patient with the hip disease (often referred to as simply Perthes disease) will do over the long term.

"Physicians make decisions based on the system, but nobody had ever proven its reliability," said Stuart Weinstein, M.D., UI professor of orthopaedic surgery and the study's corresponding author. "Our findings indicate that the system has poor reliability. Consequently, the validity of any treatment decisions, outcome evaluations or epidemiological studies based on this system must be called into question."

Perthes disease is a condition that affects young children, most commonly between the ages of 4 and 10. It involves the loss of blood supply to the upper end of the femur, which eventually leads to deformation of the femoral head. If untreated, the disease may lead to degenerative arthritis. The cause of the disease is unknown, although roughly one in 12,000 children has the disease. The UI Hospitals and Clinics treats between 25 and 30 children with Perthes disease each year.

The Stulberg system establishes five patient outcome categories based on radiographs. Each category describes a different shape or relationship between the femoral head and the hip socket. Each category is associated with the potential for, and the onset of, degenerative joint disease. For example, children with category I hips are at low risk for early-onset degenerative disease, whereas children with category IV hips frequently develop arthritic changes in early adulthood. The system has also been used to evaluate the effectiveness of various treatments for Perthes disease.

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Contact: Jennifer Cronin
jennifer-cronin@uiowa.edu
319-335-9917
University of Iowa
31-Oct-1999