Current Trends of Osteonecrosis of the Femoral Head in Taiwan and China

Osteonecrosis of the femoral head (ONFH) is a disabling condition characterized by the disruption of intravascular blood flow, direct cellular toxicity, and impaired mesenchymal cellular differentiation with subsequent bone death [1–3]. Collapse of the normal spherical head contour with progression to secondary arthritis occurs along a continuum of disease progression. There are an estimated 20,000–30,000 new cases of ONFH diagnosed annually in the USA, with the preponderance among young, active men between the ages of 20 and 50 years [4]. It is evident that ethnic differences in the index diagnosis for hip arthroplasty do exist. In a comparative study by Hoaglund, the incidence of ONFH as an indication for THR in Japanese patients, an Asian population, was four times that of American Caucasian patients [5]. Therefore, because the population size of China, for example, is four and one-half times that of the USA, it is reasonable to conclude that there may be 360,000–540,000 new cases diagnosed in China annually. Osteoarthritis is the main indication for THRs performed in the Caucasian populations [6], but ONFH is the main indication for hip arthroplasty in Asian populations. For instance, in Hong Kong, 45.6% of THRs were performed under the diagnosis of ONFH [7], while only 3% of THRs in the UK [8] and 10% of THRs in the USA [9] are performed for ONFH. In addition, patients with ONFH are usually young men of working age; therefore, the socioeconomic impact of ONFH is great in Asian countries. According to the National Health Insurance Database, ONFH accounted for 46.9% of the THRs in Taiwan. Among them, 79% were male patients with a mean age of around 50 years [10]. The high prevalence of ONFH in Taiwanese or other Asian populations may be associated with intravascular coagulation abnormalities. Studies of the national health insurance database found that the relative risks of major cerebrovascular or cardiovascular incidence as well as unprovoked venothromboembolic events in patients with ONFH were significantly higher than those of the healthy controls [11–13]. Genetic polymorphisms of coagulation factor V, methylenetetrahydrofolate reductase, and nitric oxide synthase were also significantly higher in ONFH patients with abnormal coagulation profiles [14–16]. Although the prevalence of ONFH is high in Taiwan and China, most of the patients are delayed in diagnosis and treatment. The majority are treated by joint replacements and only 10% of them are managed by joint preservation measures.