Morphological and biomechanical model for predicting the course of avascular necrosis of the femoral head

Objective. To create an integrated model for predicting the course of avascular necrosis. Materials and methods. Data from 126 patients aged 18–65 years with avascular necrosis of the femoral head in stages I–III according to Ficat and Arlet were analyzed. The study used radiography, magnetic resonance imaging, and computed tomography, assessment of necrosis localization (Japanese Orthopaedic Association classification), lesion size (Steinberg), biomechanical parameters, and clinical scales. The results of the pathomorphological study were supplemented by an assessment of microcirculation and trabecular structure. The prognostic model was validated by the area under the ROC curve, Kappa coefficients, Intraclass Correlation Coefficient, and correlation analysis. Results. Classifications of avascular necrosis only partially reflected the risk of progression. The new integrated system showed higher prognostic accuracy (area under the ROC curve = 0.89), especially for type C–D lesions according to the Japanese Orthopaedic Association classification and necrosis of more than 30%. The most important determinants of collapse were lateral localization of the lesion, early loss of sphericity, and displacement of the load vector. Conclusions. The integrated classification allows for more accurate stratification of the risk of subchondral collapse than the Ficat and Arlet, Association Research Circulation Osseous, and Steinberg classifications, and personalization of the choice of treatment tactics–from conservative methods to surgical interventions.