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% boneresorption 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.

What Is New in Stage 3 of the 2019 Revised Association Research Circulation Osseous Staging System of Osteonecrosis of the Femoral Head: A Relationship to Bone Resorption

“…4). The bone resorption area was defined as low-density lucent areas in which the trabecular structure was no longer present, connected to the interface between the necrotic region and extranecrotic region, and no surrounding sclerotic margin 18,21–23 . The “bone resorption area” was a “radiolucent change” initiated by excessive osteoclastic activity in the reparative interface zone, and histologically, this zone was called “fibrovascular reparative zone” because this “region” consisted of vascularized fibrous and granulation tissue 3 .…”

“…The location of bone resorption area was evaluated on coronal and axial images, dividing the femoral head into C1 (lateral), C2 (central), and C3 (medial) sections by the 3-pillar classification system on coronal image and into A1-A4 regions by 2 lines. One line was through the long axis of the femoral neck, and the other was a perpendicular line through the center of the femoral head on axial image 21,25 . All hip CT scans were evaluated by 2 radiologists (12 years and 1 year of experience) in a blinded fashion.…”

“…The bone resorption area was defined as low-density lucent areas in which the trabecular structure was no longer present, connected to the interface between the necrotic region and extranecrotic region, and no surrounding sclerotic margin. 18,[21][22][23] The "bone resorption area" was a "radiolucent change" initiated by excessive osteoclastic activity in the reparative interface zone, and histologically, this zone was called "fibrovascular reparative zone" because this "region" consisted of vascularized fibrous and granulation tissue. 3 Two terms had similar histological features such as fibrous granulation presenting low density (average CT values of 70.7 HU), 24 but the former emphasized the radiologic finding and the latter indicated the histologic site.…”

Less sclerotic microarchitecture pattern with increased bone resorption in glucocorticoid-associated osteonecrosis of femoral head as compared to alcohol-associated osteonecrosis of femoral head

“…Specifically, along the supero-inferior orientation, the femoral head was divided into three main regions with reference to the boundary of the necrotic lesion: superior region (necrotic region), central region (i.e. reactive interface or necrotic-normal junction region), and inferior region (normal region); along the medio-lateral orientation, the femoral head was divided into another three main regions with reference to the China-Japan Friendship Hospital (CJFH) three−pillar system: medial region, central region and lateral region ( 23 – 25 ). The ROIs of reactive interface were routinely located 0.5 mm from the boundary of the necrotic lesion.…”

“…We therefore propose that the bone microarchitectural and histopathological features of the femoral head should differ between GONFH and AONFH. In order to address this, we evaluated microarchitecture, bone remodeling activity and histopathological alterations of trabecular bone in different regions of the femoral head based on the three-pillar system ( 23 – 25 ) from patients with GONFH and AONFH, using micro-CT, decalcified and undecalcified bone histology.…”