Prediction of Osteonecrosis Collapse of the Femoral Head Based on the Proportion of the Proximal Sclerotic Rim

Purpose: The purpose of this study was to predict ONFH-induced collapse based on the percentage of the proximal sclerotic rim.

Methods: In total, 101 patients satisfying the inclusion criteria who received treatment at Guang'anmen Hospital were enrolled. Bilateral hip-joint computed tomography (CT) of the necrotic tissue was performed, and the largest layer within the coronal CT images was selected together with its anterior and posterior layers to calculate the proportion of the proximal sclerotic rim. The patients were divided into collapse and non-collapse groups, and the difference in the proportions of their proximal sclerotic rims was analysed. Specifically, a receiver operating characteristic (ROC) curve was created. The proportion of the proximal sclerotic rim represented by the maximal Youden's index was used as the reference value for collapse prediction, and its predictive value was assessed.

Results: The proportion in the collapse group was 13.11 ± 10.65 %, whereas the proportion in the non-collapse group was 51.91 ± 21.29 % (P < 0.01). Additionally, the proportion corresponding to the maximal Youden's index (0.902) was 29.24 %. For clinical convenience, 30 % was selected as the reference value for collapse prediction, with 97.30 % sensitivity, 87.5 % specificity, 94.01 % accuracy, a positive likelihood ratio (LR) of 7.78, and a negative LR of 0.03. Therefore, the proportion of the proximal sclerotic rim is of great significance in predicting ONFH-induced collapse, and 30 % could be used as the critical value in clinical practice.

Conclusion: When the proportion is >30 %, the collapse risk is low, whereas at <30 %, the risk is high, and effective mechanical support should be provided.