Aro H T, Wippermann B W, Hodgson S F, Wahner H W, Lewallen D G, Chao E Y
Mayo Clinic, Rochester, Minnesota 55905.
J Bone Joint Surg Am. 1989 Aug;71(7):1020-30.
An experiment was designed to determine whether the material properties of fracture callus can be predicted by the measurement of mineral density. Rat tibiae that had a closed fracture were used to obtain uniform specimens of fracture callus at sequential stages of healing. An in vitro indentation test was done and tissue was biopsied, using a trephine, to determine the hardness and calcium content of a standardized area of callus tissue. The hardness of the callus was correlated with the mineral density of the local tissue, which initially had been measured non-invasively with single-photon-based micro-bone densitometry. The progress of differentiation and remodeling of callus was determined by comparative planimetric and microradiographic analyses of tissue. Determinations of density showed a linear correlation with concentrations of a hydroxyapatite equivalent solution (r = 0.997, p less than 0.001), with the ash weight of control specimens of cortical-trabecular bone (r = 0.998, p less than 0.001), and with the calcium content (micrograms per cubic millimeter) of the fracture callus (r = 0.854, p less than 0.001). The hardness of the callus had a non-linear relationship (r = 0.959, p less than 0.005) with the mineral density per volume of tissue, as measured by micro-bone densitometry.
The appearance of fracture callus on conventional radiographs is an important clinical finding in the assessment of fracture-healing. It is, however, an unreliable predictor of the strength of the union of the fracture. Three-dimensional imaging and quantification of bone mineral provide additional data about the quality and geometry of fracture callus. Our study showed that mineral content per unit of volume is a good index of hardness of the fracture callus. Thus, quantitative imaging may be useful clinically for monitoring fracture-healing.
设计了一项实验，以确定是否可以通过测量矿物质密度来预测骨折骨痂的材料特性。使用有闭合性骨折的大鼠胫骨，在愈合的连续阶段获取均匀的骨折骨痂标本。进行了体外压痕试验，并使用环钻进行组织活检，以确定骨痂组织标准化区域的硬度和钙含量。骨痂的硬度与局部组织的矿物质密度相关，局部组织的矿物质密度最初是通过基于单光子的微型骨密度测定法进行非侵入性测量的。通过对组织进行比较平面测量和显微放射照相分析来确定骨痂的分化和重塑进程。密度测定显示与羟基磷灰石等效溶液的浓度呈线性相关（r = 0.997，p < 0.001），与皮质 - 小梁骨对照标本的灰重呈线性相关（r = 0.998，p < 0.001），与骨折骨痂的钙含量（每立方毫米微克数）呈线性相关（r = 0.854，p < 0.001）。通过微型骨密度测定法测量，骨痂的硬度与每单位体积组织的矿物质密度呈非线性关系（r = 0.959，p < 0.005）。
传统X线片上骨折骨痂的表现是评估骨折愈合的一项重要临床发现。然而，它是骨折愈合强度的不可靠预测指标。骨矿物质的三维成像和定量分析提供了有关骨折骨痂质量和几何形状的额外数据。我们的研究表明，单位体积的矿物质含量是骨折骨痂硬度的良好指标。因此，定量成像在临床上可能有助于监测骨折愈合。
