Department of Biomedical Engineering, University of Rochester, 207 Robert B. Goergen Hall, Rochester, NY 14642, USA.
The Center for Musculoskeletal Research, University of Rochester Medical Center, 601 Elmwood Avenue, Box 665, Rochester, NY 14642, USA.
J Biomech. 2021 Feb 12;116:110243. doi: 10.1016/j.jbiomech.2021.110243. Epub 2021 Jan 13.
Bone fragility and fracture risk are assessed by measuring the areal bone mineral density (aBMD) using dual-energy X-ray absorptiometry (DXA). While aBMD correlates with bone strength, it is a poor predictor of fragility fracture risk. Alternatively, fracture toughness assesses the bone's resistance to crack propagation and fracture, making it a suitable bone quality metric. Here, we explored how femoral midshaft measurements from DXA, micro-computed tomography (µCT), and Raman spectroscopy could predict fracture toughness. We hypothesized that ovariectomy (OVX) decreases aBMD and fracture toughness compared to controls and we can optimize a multivariate assessment of bone quality by combining results from X-ray and Raman spectroscopy. Female mice underwent an OVX (n = 5) or sham (n = 5) surgery at 3 months of age. Femurs were excised 3 months after ovariectomy and assessed with Raman spectroscopy, µCT, and DXA. Subsequently, a notch was created on the anterior side of the mid-diaphysis of the femurs. Three-point bending induced a controlled fracture that initiated at the notch. The OVX mice had a significantly lower aBMD, cortical thickness, and fracture toughness when compared to controls (p < 0.05). A leave one out cross-validated (LOOCV) partial least squares regression (PLSR) model based only on the combination of aBMD and cortical thickness showed no significant predictive correlations with fracture toughness, whereas a PLSR model based on principal components derived from the full Raman spectra yielded significant prediction (r = 0.71, p < 0.05). Further, the PLSR model was improved by incorporating aBMD, cortical thickness, and principal components from Raman spectra (r = 0.92, p < 0.001). This exploratory study demonstrates combining X-ray with Raman spectroscopy leads to a more accurate assessment of bone fracture toughness and could be a useful diagnostic tool for the assessment of fragility fracture risk.
骨脆性和骨折风险通过使用双能 X 射线吸收法（DXA）测量骨面积密度（aBMD）来评估。虽然 aBMD 与骨强度相关，但它是脆性骨折风险的预测指标较差。相反，断裂韧性评估了骨骼抵抗裂纹扩展和断裂的能力，使其成为一种合适的骨质量指标。在这里，我们探讨了 DXA、微计算机断层扫描（µCT）和拉曼光谱测量的股骨中段测量值如何预测断裂韧性。我们假设去卵巢（OVX）会降低 aBMD 和骨折韧性与对照组相比，我们可以通过结合 X 射线和拉曼光谱的结果来优化骨质量的多变量评估。3 个月大的雌性小鼠接受 OVX（n=5）或假手术（n=5）。OVX 后 3 个月切除股骨，并用拉曼光谱、µCT 和 DXA 进行评估。随后，在前侧股骨中段创建一个缺口。三点弯曲在缺口处引发受控骨折。与对照组相比，OVX 小鼠的 aBMD、皮质厚度和断裂韧性显着降低（p<0.05）。仅基于 aBMD 和皮质厚度组合的留一法交叉验证（LOOCV）偏最小二乘回归（PLSR）模型与断裂韧性无显着预测相关性，而基于全拉曼光谱衍生的主成分的 PLSR 模型则具有显着的预测性（r=0.71，p<0.05）。此外，通过合并 aBMD、皮质厚度和拉曼光谱的主成分，PLSR 模型得到了改善（r=0.92，p<0.001）。这项探索性研究表明，将 X 射线与拉曼光谱相结合可更准确地评估骨断裂韧性，并且可能是评估脆性骨折风险的有用诊断工具。
