OBJECTIVE To report in vivo measurements of lumbar facet joint subchondral bone mineral density used in the description of facet joint loading patterns and to interrogate if low back pain is associated with changes in subchondral bone mineral density. MATERIALS AND METHODS In vivo measurements of lumbar facet joint subchondral bone mineral density (L1/2 to L5/S1) in Hounsfield units were performed on 89 volunteers (56 controls and 33 with low back pain) by computed tomography osteoabsorptiometry at subchondral regions between 1.5 mm and 2.5 mm below the joint surface. The facet surface was divided into five topographic zones: cranial, lateral, caudal, medial, and central. RESULTS We analyzed 1780 facet joint surfaces. Facets were denser (p < 0.0001) both in superior facets and in low back pain subjects (p < 0.0001). For the entire cohort, the facet center zone subchondral bone mineral density was higher (p < 0.0001) than that of the peripheral zones. The analyses indicate that subchondral bone mineral density is highest in patients with low back pain, the superior facets, and the center zone of the facets. CONCLUSIONS Subchondral bone mineral density is thought to reflect cumulative, long-term distribution of stress acting on a joint. This work shows that higher subchondral bone mineral density values in the center zone indicate predominant stress transmission through the center of the facet joints. Finally, the greater subchondral bone mineral density in patients with low back pain may reflect both increased load bearing by the facets secondary to disc degeneration and misdistribution of loading within the joint.

中文翻译：

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下腰痛和无症状受试者的腰椎小关节软骨下骨密度。

目的报告体内对小关节负荷模式描述中腰小关节软骨下骨矿物质密度的测量结果，并询问腰痛与软骨下骨矿物质密度的变化是否相关。材料与方法在89例志愿者（56名对照者和33名腰背痛患者）中，通过计算机层析X线骨密度测定法在1.5之间的软骨下区域，对Hounsfield单位的腰椎小关节软骨下骨矿物质密度（L1 / 2至L5 / S1）进行了体内测量。距接合面以下2.5毫米和2.5毫米。刻面分为五个地形区域：颅骨，外侧，尾部，内侧和中央。结果我们分析了1780个小关节表面。上面部和下腰痛受试者中的面部均较密（p <0.0001）。对于整个队列 小平面中心区软骨下骨矿物质密度高于周围区域（p <0.0001）。分析表明，腰痛，上小平面和小平面中心区域的患者软骨下骨矿物质密度最高。结论软骨下骨矿物质密度被认为反映了作用在关节上的应力的累积，长期分布。这项工作表明，在中央区域，软骨下骨矿物质密度较高，表明应力主要通过小关节的中心传递。最后，腰痛较低的患者软骨下骨矿物质密度更高，可能反映了继发于椎间盘退变的小平面所承受的负荷增加以及关节内负荷分布不均。