Robertson Douglas D, Beck Thomas J, Chan Brandon W, Scott William W, Sharma Gulshan B, Maloney William J
Department of BioEngineering, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
J Orthop Res. 2007 Oct;25(10):1343-50. doi: 10.1002/jor.20419.
Pathologic fracture is a significant problem for individuals with metastatic bone disease. Current guidelines for prophylactic internal fixation are neither reliable nor easily applied. The purpose of this study was to validate dual-energy X-ray absorptiometry (DXA) as an accurate method for estimating torsional bone strength of diaphyseal bone with endosteal lytic lesions. Endosteal lesions of varying sizes were simulated in the diaphyses of 12 adult cadaveric femurs. Unaltered contralateral femurs served as matched controls. Machined lesions ranged from 3 to 6.5 cm in length, 1 to 3 cm in width, 15 to 48 cm(2) in elliptical area, with 10% to 100% removal of the cortical thickness. Morphology and density data obtained from DXA images were used to estimate torsional strength. All femora were mechanically tested to failure in torsion. Physically measured torsional strength was not significantly correlated to lesion elliptical area (r = 0.542, p > 0.05) or percentage cortical thickness removed (r = 0.257, p > 0.05). Measured torsional strength was significantly correlated to DXA-based torsional strength estimates (r = 0.855, p < 0.01). Lesion size alone did not correlate with the strength of bones with simulated endosteal lytic lesions. In contrast, calculations based on DXA (morphology, density) did correlate with torsional strength. This is the first step in the development of a DXA-based tool for objectively estimating bone strength in the presence of endosteal lytic lesions.
病理性骨折是转移性骨病患者面临的一个重大问题。目前的预防性内固定指南既不可靠也不易应用。本研究的目的是验证双能X线吸收法（DXA）作为一种准确的方法，用于评估具有骨内膜溶解性病变的骨干骨的扭转骨强度。在12具成年尸体股骨的骨干中模拟了不同大小的骨内膜病变。未改变的对侧股骨作为匹配对照。加工后的病变长度为3至6.5厘米，宽度为1至3厘米，椭圆面积为15至48平方厘米，皮质厚度去除10%至100%。从DXA图像获得的形态学和密度数据用于估计扭转强度。所有股骨均进行扭转力学测试直至失效。物理测量的扭转强度与病变椭圆面积（r = 0.542，p > 0.05）或皮质厚度去除百分比（r = 0.257，p > 0.05）无显著相关性。测量的扭转强度与基于DXA的扭转强度估计值显著相关（r = 0.855，p < 0.01）。仅病变大小与具有模拟骨内膜溶解性病变的骨骼强度无关。相比之下，基于DXA（形态学、密度）的计算与扭转强度相关。这是开发基于DXA的工具以客观评估存在骨内膜溶解性病变时骨强度的第一步。
