基于影像学及计算机图像处理方法研究活体腰椎小关节结构三维分布

In vivo study on three-dimensional structure of lumbar facet joints based on computer-assisted medical image processing method

目的基于小关节三维重建图像分析软骨下皮质骨厚度、小关节面面积及关节间隙宽度的三维分布情况,研究其结构特点及变化规律,并比较腰痛患者及健康人中这些参数的差别。方法对90名研究对象分别行仰卧位CT扫描,获取L1～S1 5个节段小关节的二维图像,重建后分别获得软骨下皮质骨、小关节面及关节间隙的三维面点云图。研究上述参数在整个关节面上、以及关节面的不同区域的分布特点,比较它们在不同腰椎节段、性别、年龄及症状组中的差异。结果 (1)软骨下皮质骨厚度方面,在上关节突,头端区最厚;在下关节突,尾端区最厚。中央区的厚度明显小于其他各区。各区之间的差别在低位节段腰椎中(L4/5,L5/S1)较明显。(2)小关节平均面积为(173.2±3.6)mm2,且随腰椎节段及年龄的增加而增大,L4/5节段以下及40岁以上更加明显。腰痛患者上关节突关节面的面积明显较下关节突关节面的面积大(L5/S1节段除外)。腰痛患者的小关节面积明显大于健康人。(3)小关节间隙平均宽度为(1.46±0.08)mm,随年龄增加而变窄,40岁以上者更明显,女性均较男性宽,腰痛患者则显著变窄。分区比较时,关节面头侧关节间隙较尾侧间隙宽,中央区的间隙普遍较周围区宽,这些差别在腰痛患者及下3个节段中更明显。结论计算机图像处理及重建分析技术可以较准确的测量三维空间内形状复杂的小关节的相关参数。小关节各结构在三维空间的分布具有一定特点,这些特点与关节面形态、关节间应力及关节退变等因素有关,反映了长期的负荷状态下人体结构的适应性改变。

Objective To study three-dimensional feature of the thickness of subchondral cortical bone,the surface area and space width of the facet joints as well as its morphological characteristics and variation,and to compare the differences of these parameters in patients with low back pains and healthy people,based on three-dimensional reconstruction images of the facet joints.Methods CT scanning from L1/2 to L5/S1 at supine position was performed on 90 subjects to obtain two-dimensional images of the facet joints and three-dimensional point-cloud data of the subchondral cortical bone,the surface area and space width of the facet joints after reconstruction.Distributions of these parameters between the superior and inferior facet joints and at different regions of the articular process were investigated,and differences of these parameters in lumbar segments,gender,age and symptoms were also compared.Results（1）At superior facet,the largest thickness was located at the cranial region,while at inferior facet,it was located at the caudal region.The thickness of subchondral cortical bone was significantly smaller at central region than at the other regions.A more obvious difference could be observed at the lower lumbar levels（L4/5,L5/S1）.（2）The average surface area of the facet joints was（173.2±3.6） mm2,and it was increased with the lumbar level and age increasing,especially at the L4/5 level and at the age of more than 40.The surface area of superior facet joints was significantly larger than that of inferior facet joints for patients with low back pains（except at L5/S1 level）,who had an obviously larger surface area of the facet joints than healthy people.（3）The average thickness of space width of the facet joints was（1.46±0.08） mm,and it was decreased with age decreasing,especially at the age of more than 40.The female had significantly larger space width than the male,while patients with low back pains had significantly smaller space width.At each facet joint,the space at cranial region was significantly larger than that at caudal region,and it was also significantly larger at central region than at surrounding region.These differences were more obvious at the lower three lumbar levels.Conclusions Computer-assistant image processing and reconstruction analysis techniques can accurately measure the relative parameters of lumbar facet joints with complicated structure in three-dimensional space.The feature of the facet joints was correlated with shape of the facet joint surface,stress on the joint and degeneration of the joint,so it was a reflection of adaptive changes in human body structure due to the long-term loading on the facet joint.