Prediction of the progression of femoral head collapse in ARCO stage 2-3A osteonecrosis based on the initial bone resorption lesion.

Abstract

To predict the progression of femoral head collapse in Association Research Circulation Osseous (ARCO) Stage 2-3A osteonecrosis based on the initial bone resorption lesion. A retrospective analysis of the location, attenuation, and maximum area in coronal position (MAC) of the initial bone resorption lesion in ARCO Stage 2 and 3A was conducted in 85 cases of osteonecrosis of the femoral head (ONFH). The cases were divided into rapid and slow progression groups according to whether femoral head collapse at follow-up was greater than 2 mm. The characteristics of the bone resorption lesion between the two groups were compared by analysis of variance. Receiver operating characteristic curve was used to analyze the MAC, regions of A2, and C1 of bone resorption lesion in predicting collapse progression. The MAC of initial bone resorption lesion in rapid progression group (117.8 ± 72.1 mm2) was significantly larger than slow (53.1 ± 39.5 mm2) (p < 0.001). Regions of A2 and C1 involved were significantly higher in rapid than slow progression group. The area under the receiver operating characteristic curve of MAC, regions of A2 and C1 of bone resorption lesion to predict collapse progression were 0.81, 0.72 and 0.62 respectively. A threshold MAC of 49 mm2 had sensitivity of 86.1% and specificity of 61.9% to predict collapse progression. The MAC of initial bone resorption lesion in ARCO Stage 2-3A ONFH can predict the progression of femoral head collapse. If it is greater than 49 mm2 and located in regions of A2 and C1, the possibility of rapid progression is high, active monitoring and intervention should be recommended. This study is the first to find that the maximum area in coronal position of initial bone resorption lesion in ARCO Stage 2 or 3A can predict progression of the femoral head collapse with a threshold of 49 mm2. If the maximum area is larger than 49 mm2 and located in the anterolateral or lateral column of the femoral head, the possibility of rapid collapse progression is high, therefore, monitoring should be strengthened and active intervention should be considered.