A RISK ASSESSMENT SYSTEM FOR EARLY OSTEONECROSIS OF THE FEMORAL HEAD

Zhennan Zhang, Tong Yu, Limin Xie^*, Yubin Li, Yang Bai 

Department of Orthopedics, Guang’anmen Hospital, China Academy of Chinese Medical Sciences, Beijing 100053, China

Introduction: Collapse is a decisive factor for the prognosis of osteonecrosis of the femoral head (ONFH), and therefore, scientific and accurate assessment of the risk of femoral head collapse in an early stage has become the key to the prevention and treatment of the disease. In this paper, we performed a preliminary evaluation of the clinical value of the risk assessment system for early ONFH. 

Materials and methods: From October 2015 to December 2018, 247 cases of ONFH (360 hips) at Steinberg stage I-III were collected in the Outpatient Clinic of Orthopedics, Guang'anmen Hospital, China Academy of Chinese Medical Sciences. The patients were grouped into no risk, low-risk, medium-risk, and high-risk groups according to the results of the early ONFH risk assessment system, and they were given corresponding clinical treatment measures. The Harris score was used to evaluate hip function. The Steinberg staging system was used as the imaging grading criteria, and Steinberg stage IV and above were defined as ONFH collapse. 

Results: A total of 229 cases of ONFH (331 hips) were followed up, and the average follow-up time was 28 months (12-42 months). The Harris score before treatment was 77.84±12.96, and the score after treatment was higher, 85.69±12.29. The difference was statistically significant (P<0.001). By the end of the follow-up, 112 hips had collapsed, for a collapse rate of 33.84%; in the low-risk group, 3 hips out of 134 collapsed, for a collapse rate of 2.24%; in the medium-risk group, 3 hips out of 22 collapsed, for a collapse rate of 13.64%; and in the high-risk group, 106 hips out of 175 collapsed, for a collapse rate of 60.57%; these rates were lower than corresponding rates reported in relevant literature. 

Conclusions: Using this early ONFH risk assessment system in the treatment of early ONFH achieved a lower collapse rate than those in the natural course of disease progression and in literature reports.