The Proximal Femoral Musculature: A new Risk Factor for Hip Fracture

描述(申请人提供)：骨质疏松性骨折具有复杂的病因，涉及骨骼脆性、跌倒的风险以及一旦开始跌倒时对跌倒的反应受损。目前，双X射线骨密度仪(DXA)和定量计算机体层摄影术(QCT)等定量骨评估可作为骨骼强度的替代物，但作为骨折风险的替代物的价值有限，因为它们不能提供有关非骨骼危险因素(如跌倒)的信息。研究表明，跌倒的风险与肌肉力量的减少有关，特别是股骨近端的肌肉力量。髋部的QCT图像提供了有关股骨近端肌肉的大小和组成的信息，对不同骨骼部位的研究表明，肌肉力量和肌肉大小之间的相关性以及通过X射线CT测量的衰减。在我们的实验室里，我们最近已经证明，肌肉大小和衰减数据与CT骨骼测量相结合，显著提高了CT测量的分辨率。在这里，我们建议开发计算机算法来评估QCT髋关节图像中的肌肉大小和衰减，前瞻性地验证这些测量方法与髋部QCT骨骼变量结合使用时可以改善骨折预测，并确定它们预测骨折的机制。研究队列将从5000名老年人中挑选出来，他们已经在预期年龄基因/环境-雷克雅未克(AGES-R)研究中进行了基线QCT检查，目前正在跟踪调查髋部和其他骨骼部位的意外骨折。该研究计划的最终目标是开发一种重要的非骨骼风险因素的定量评估，该评估可以与QCT骨骼测量相结合，从而显著提高诊断效率，而不需要额外的程序成本。公共卫生研究进展：基于临床可用的髋关节QCT骨骼成像的肌肉量化方法的发展是改善髋部骨折风险评估的重要途径。它可能会通过提供一种反映跌倒风险的额外的非骨骼测量来修改对髋部骨折风险患者的治疗。这种定量测量是可以修改的，并可能成为特定运动或药物疗法的治疗终点。

DESCRIPTION (provided by applicant): Osteoporotic fracture has a complex etiology involving skeletal fragility, risk of falling, and impaired reaction to a fall once it is initiated. Currently, quantitative bone assessments such as dual x-ray absorptiometry (DXA) and quantitative computed tomography (QCT) act as surrogates for skeletal strength but are of limited value as surrogates of fracture risk because they do not provide information on non-skeletal risk factors such as falls. Studies have shown that fall risk is associated with reduced muscle strength, particularly of the proximal femoral musculature. The QCT image of the hip provides information on the size and composition of the proximal femoral muscles, and studies at various skeletal sites have shown correlations between muscle strength and muscle size and attenuation measured by x-ray CT. In our laboratory, we have recently shown that combination of muscle size and attenuation data with the CT skeletal measures markedly improves the discriminatory power of the CT measurement. Here, we propose to develop computer algorithms to assess muscle size and attenuation from QCT hip images, prospectively validate that these measures improve fracture prediction when used in combination with hip QCT bone variables, and determine the mechanism by which they predict fracture. The study cohort will be selected from 5000 elderly individuals who have had baseline QCT examinations in the prospective Age Gene/Environment -Reykjavik (AGES-R) study and who are now being followed for incident fractures of the hip and other skeletal sites. The ultimate goal of this research program is to develop a quantitative assessment of an important non-skeletal risk factor that can be combined with QCT bone measurements, thus significantly improving diagnostic efficacy without the cost of an additional procedure. PUBLIC HEALTH RELEVENCE: Development of a muscle quantification procedure based on clinically available hip QCT skeletal imaging is an important pathway to improving estimation of hip fracture risk. It would potentially modify management of patients at risk for hip fractures by providing an additional non-skeletal measure reflective of fall risk. This quantitative measurement is modifiable and could become a treatment endpoint for specific exercise or drug therapies.