Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestrasse 59, 22529 Hamburg, Germany; Department of Orthopedics, University Medical Center Hamburg-Eppendorf, Martinistraße 52, 20246 Hamburg, Germany.
Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestrasse 59, 22529 Hamburg, Germany.
Bone. 2018 Jul;112:187-193. doi: 10.1016/j.bone.2018.04.018. Epub 2018 Apr 19.
The osteocytic lacunar network is considered to be an integral player in the regulation of bone homeostasis, and reduction in osteocytes is associated with reduced bone strength. Here, we analyzed site-specific patterns in osteocyte characteristics and matrix composition in the cortical compartment of the femoral neck to reveal the structural basis of its fragility.
Cross-sections of the human femoral neck - one of the most common fracture sites - were acquired from 12 female cadavers (age 34-86 years) and analyzed with backscattered scanning electron microscopy and high-resolution micro-computed tomography (μ-CT). The 2D/3D density and size of the osteocyte lacunae as well as bone mineral density distribution (BMDD) were measured in two regions subject to different biomechanical loads in vivo: the inferomedial (medial) region (habitually highly loaded in compression) and the superolateral (lateral) region (lower habitual loading intensity). Using quantitative polarized light microscopy, collagen fiber orientation was quantified in these two regions, accordingly.
In 2D measurements, the inferomedial region displayed lower mineralization heterogeneity, 19% higher osteocyte lacunar density (p = 0.005), but equal lacunar size compared to the superolateral region. 3D measurements confirmed a significantly higher osteocyte lacunar density in the inferomedial region (p = 0.015). Osteocyte lacunar density decreased in aged individuals, and inter-site differences were reduced. Site-specific osteocyte characteristics were not accompanied by changes in collagen fiber orientation.
Since osteocyte characteristics may provide valuable insights into bone mechanical competence, the variations in osteocyte properties might reflect the increased fracture susceptibility of the superolateral neck.
骨细胞陷窝网络被认为是调节骨稳态的一个组成部分，骨细胞的减少与骨强度降低有关。在这里，我们分析了股骨颈皮质区骨细胞特征和基质组成的特定部位模式，以揭示其脆弱性的结构基础。
从 12 名女性尸体（年龄 34-86 岁）中获得了人类股骨颈的横截面 - 最常见的骨折部位之一 - 并用背散射扫描电子显微镜和高分辨率微计算机断层扫描（μ-CT）进行了分析。在体内受到不同生物力学负荷的两个区域（即内侧（内侧）区域（习惯性高压缩负荷）和外侧（外侧）区域（习惯性较低的加载强度））测量了骨细胞陷窝的 2D/3D 密度和大小以及骨矿物质密度分布（BMDD）。使用定量偏振光显微镜，在这两个区域相应地量化了胶原纤维取向。
在 2D 测量中，内侧区域的矿化异质性较低，骨细胞陷窝密度高 19%（p=0.005），但与外侧区域相比，陷窝大小相等。3D 测量证实内侧区域的骨细胞陷窝密度明显更高（p=0.015）。骨细胞陷窝密度随年龄增长而降低，且个体间差异减小。特定部位的骨细胞特征没有伴随着胶原纤维取向的变化。
由于骨细胞特征可能为骨力学性能提供有价值的见解，因此骨细胞特性的变化可能反映了外侧颈部骨折易感性的增加。
