DEAR EDITOR,rnOsteonecrosis is a common human disease in orthopedics.It is difficult to treat, and half of patients may need artificial joint replacement, resulting in a considerable economic burden and a reduction in quality of life.Hormones are one of the major causes of osteonecrosis and high doses of corticosteroids are considered the most dangerous factor.Because of the complexity of treatment, we still need a better animal model that can be widely used in drug development and testing.Tree shrews are more closely related to primates than rodents.As such, we constructed a successful tree shrew model to establish and evaluate steroid-associated osteonecrosis (SAON).We found that low-dose lipopolysaccharide (LPS) combined with high-dose methylprednisolone (MPS) over 12 weeks could be used to establish a tree shrew model with femoral head necrosis.Serum biochemical and histological analyses showed that an ideal model was obtained.Thus, this work provides a useful animal model for the study of SAON and for the optimization of treatment methods.