Artikel
Stress distribution around the lateral boundary of the necrotic lesion in the non-collapsed femoral head with osteonecrosis
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Veröffentlicht: | 23. Oktober 2017 |
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Gliederung
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Objectives: Although the mechanism of femoral head collapse in osteonecrosis is still controversial, we have demonstrated that collapse consistently involved a fracture at the lateral boundary of the necrotic lesion in morphological analyses of the resected femoral head. The purpose of this study was to examine stress distribution around the lateral boundary of the necrotic lesion in the non-collapsed femoral head with osteonecrosis based on a biological data-based finite element analyses (FEA).
Methods: Image data of 12 hip joints hip joints without collapse of the femoral head in 12 patients were used. According to the classification of association research circulation osseous (ARCO), these 12 femoral heads were classified into three groups: osteonecrosis with sclerotic changes in the reparative area (Stage 2, n = 5), osteonecrosis without sclerotic changes in the reparative area (Stage 1, n = 5) and non-osteonecrosis (Control, n = 2). Finite element models were generated from each CT data using Mechanical Finder version 7.0 (Research Center for Computational Mechanics Inc., Tokyo, Japan). Distribution of the equivalent stress on FEA was assessed around the lateral boundary of the necrotic lesion just below the bone surface in the same slices of both MRI and CT, including the mid-coronal and anterior coronal plane where the necrotic area was the widest. In control group, distribution of the equivalent stress was assessed around the area corresponding to the lateral boundary of the necrotic lesion in Stage 2 group.
Results and Conclusion: Distribution of the equivalent stress was equally observed just below the bone surface of the femoral head in both Stage 1 group (Figure) and Control group. On the other hand, in Stage 2 group, distribution of the equivalent stress was eccentrically located around the lateral boundary of the necrotic lesion (Figure).
In conclusion, the current in vivo FEA study indicated that distribution of the equivalent stress was eccentrically located around the lateral boundary of the necrotic lesion in Stage 2 group, while it was not apparently observed in Stage 1 group.