Three-Dimensional Distribution of Bone-Resorption Lesions in Osteonecrosis of the Femoral Head Based on the Three-Pillar Classification

Abstract

Objective: To investigate three-dimensional distribution of bone-resorptive lesions based on the three-pillar classification and its effect on the disease progression of osteonecrosis of the femoral head (ONFH).

Methods: A total of 194 femoral head CT images from 117 patients diagnosed with ARCO stage II and III ONFH were retrospectively reviewed from April 2014 to February 2019. Three-dimensional structures of the femoral head and the bone-resorptive lesions were reconstructed. Using the three-pillar classification and coronal plane of the femoral head, we divided each femoral head into six regions to observe the location characteristics of bone-resorption lesions, and explore the destruction of different areas of the femoral head by the bone-resorptive lesions. Then the hips were divided into two groups based on whether they contained bone-resorption lesions and compared the difference of stage II and stage III between the two groups.

Results: The regional distribution revealed 39 (27.27%), 55 (38.46%), six (4.20%), 23 (16.08%), 17 (11.89%) and three (2.10%) bone-resorptive lesions in regions I, II, III, IV, V and VI respectively. The lateral pillar, AL (I + IV), contained 44.76% of the lesions, central pillar, C (II + V), 48.95%, and medial pillar, M (III + VI), 6.29%. Moreover, there were 81.82% bone-resorption lesions in anterolateral pillar, AL (I + II + IV), and 18.18% in posteromedial pillar, PM (III + V + VI). In all ONFH hips, the lateral pillar of 81(88.04%) femoral heads were affected, the central pillar of 84 (91.30%) femoral heads were affected, and the medical pillar of 29 (31.52%) femoral heads were affected. The ratio of ARCO stage III in the group with bone-resorption lesions was significantly higher than that of the group without bone-resorption lesions (76.09% vs 30.39%, P < 0.001).

Conclusions: This study demonstrated that the bone-resorption lesions are mainly distributed in the lateral and central pillar of the femoral head, and the two pillars of the femoral head are usually involved by bone-resorption lesions. Furthermore, the ratio of ARCO stage III in the group with bone-resorption lesions was significantly higher than that of the group without bone-resorption lesions, suggesting that the bone-resorption lesions might accelerate the progression of ONFH.

Keywords: Bone-resorptive lesions; Collapse; Osteonecrosis of the femoral head; Three-dimensional distribution; Three-pillar classification.