[Clinical epidemiology of hip and knee joint arthroses: an overview of the results of the "Ulm Osteoarthrosis Study"].

AIM OF STUDY: To summarize the strategy of patient recruitment, applied methods and published results within the Ulm Osteoarthritis Study, a multicenter cross-sectional survey of patients with advanced hip and knee osteoarthritis.

METHODS: 420 patients with hip OA and 398 patients with knee OA scheduled for unilateral total joint replacement in four hospitals in the southwestern part of Germany underwent detailed clinical investigations and a standardized interview in addition to radiographic analyses of ipsilateral and contralateral hip or knee joint and both hands. Odds ratios and 95% confidence intervals for the association of different possible risk factors with OA patterns (unilateral, bilateral and generalized OA) were calculated with logistic regression, adjusting for potential confounders.

RESULTS: In 41.7% of patients with hip OA and 33.4% of patients with knee OA, an underlying pathological condition allowed a classification as secondary OA. 82.1% of patients with hip and 87.4% of patients with knee OA had bilateral disease. Generalized OA (GOA) was found in 19.3 and 34.9%, respectively (after adjustment for different age and sex distribution in the two patient groups; however, this difference was not any more significant). A positive association could be observed between hypercholesterolemia and GOA in knee OA patients as well as between serum uric acid and GOA in hip OA patients. Obesity and overweight were associated with bilateral knee OA, but not bilateral hip OA nor GOA.

DISCUSSION: Our innovative study design allows the non-invasive investigation of patient subgroups with established disease and a testing of relevant hypotheses in an appropriate setting. The data add to the evidence regarding the independent role of different systemic risk factors for OA. In an ongoing study the natural course of the disease of the contralateral, unoperated joint is currently being investigated in all recruited patients.