To determine the prevalence of joint specific risk factors in patients with different patterns of advanced hip and knee osteoarthritis (OA).
We performed a cross-sectional multicenter study in four orthopaedic hospitals in the southwest of Germany. A detailed medical history (date and nature of trauma, conservative and surgical treatment of congenital or acquired joint disorders known as secondary causes of OA) and radiographic evaluation (sequelae of hip dysplasia, slipped capital femoral epiphysis or other malformations) was obtained in 809 patients with advanced hip (n = 420) or knee (n = 389) osteoarthritis, which required unilateral total joint replacement. According to the presence or absence of joint specific risk factors, patients were classified as having secondary or primary (idiopathic) OA.
In 41.7% (25.5%) of patients with hip OA and 33.4% (11.1%) of patients with knee OA some predisposing abnormality of the operated (or contralateral) joint could be observed. In hip OA the underlying pathological conditions were mainly hip dysplasia (25.0% in the operated joint and 14.8% in the non-operated joint) and slipped capital femoral epiphysis (7.1% and 14.8%), while knee OA was most often associated with a history of severe trauma (28.6% and 8.3%)
While there is a lack of comparable investigations in patients with advanced knee OA, the presented data is somewhat contradictory to earlier reports of the prevalence of identified underlying risk factors in patients with hip OA. The reported differences, however, might be attributed to different methodological approaches and could also resemble recent changes in the multifactorial ethiopathologic concept of OA.