Department of Anatomy, Sri Aurobindo Institute of Medical Sciences (SAIMS), Bhawrasala, Indore, Madhya Pradesh 452 010, India.
Spine J. 2010 Jul;10(7):616-21. doi: 10.1016/j.spinee.2010.05.003.
Occurrence of transitional vertebrae at the lumbosacral junction, especially accessory lumbosacral articulations (partial sacralization of the L5 vertebrae), is not uncommon. These transitional states are frequently associated with low back pain situations requiring surgical intervention.
The study aimed to investigate the presence of distinct morphological features and structural peculiarities associated with these sacra. The features related to sacra bearing L5-S1 transitions might be significantly different from those of the normal sacra. This study tries to understand whether accessory L5-S1 articulations demonstrate altered mechanisms of load transfer as a result of structural changes at the L5-S1 junction.
Morphometric measurements of several linear dimensions and articular areas were obtained from 332 sacra. Thirty sacra demonstrated unilateral accessory facets on their ala. Twelve sacra showed bilateral accessory lumbosacral articulations. Indices were calculated based on the linear dimensions and on the surface areas of the bones to detect proportional contributions of the dimensions and surface areas to the overall structure of all the sacra.
All the parameters obtained from the transitional sacra were compared with the same parameters worked out on 290 normal sacra. All parameters in the sacra bearing accessory articulations were statistically compared with parameters in the normal sacra.
Seven linear dimensions and five surface areas were measured in 290 normal sacra. Thirty sacra bearing unilateral accessory articular facets and 12 sacra with bilateral accessory facets on their alae were measured for the same linear parameters and surface areas. Nine indices were calculated from these measurements in both the normal and transitional sacra and statistically verified.
Analysis of the results indicated that sacra bearing accessory articulations, in comparison to the normal, carried their auricular surfaces at a higher level; possessed load bearing features mainly confined to the two upper sacral segments; showed lesser distances between the facet joints; showed smaller distance of the coronal plane of the facet joints from the posterior aspect of the S1 vertebral body; exhibited smaller and more coronally oriented facet joint surfaces; and exhibited smaller body width and height. The auricular surface area and superior surface of the body of S1 in these "transitional" sacra were similar in comparison to normal sacra. Linear dimensions in sacra with bilateral accessory articulations were smaller than the ones having unilateral accessory L5-S1 articulations.
Lumbosacral accessory articulations constituted the bulk of transitional variations at the junction. Accessory articulations were unilateral (9%) and bilateral (3%) with a total of 12% of all studied samples (n=332) demonstrating this type L5-S1 transition. Sacra with lumbosacral pseudoarticulations were associated with different anatomical features in contrast to normal sacra. Analysis of these structural differences with the normal variants may possibly help in understanding the biomechanical properties at these transitional sites. Evaluation of the relative proportions of dimensions within these bones may help plan surgical interventions or probably predict the pattern of abnormal weight bearing in these sacra.
腰骶关节处的过渡椎骨，特别是附加腰骶关节（L5 椎体部分骶化）的出现并不罕见。这些过渡状态常与需要手术干预的下腰痛情况有关。
本研究旨在研究与这些骶骨相关的独特形态特征和结构特征。与正常骶骨相比，与 L5-S1 过渡相关的骶骨可能具有明显不同的特征。本研究试图了解 L5-S1 交界处的结构变化是否导致附加 L5-S1 关节的负荷传递机制发生改变。
从 332 个骶骨中获得了几个线性尺寸和关节面积的形态测量值。30 个骶骨在其翼上显示单侧附加关节面。12 个骶骨在其翼上显示双侧附加腰骶关节。基于线性尺寸和骨骼表面面积计算指数，以检测尺寸和表面面积对所有骶骨整体结构的比例贡献。
将从过渡骶骨获得的所有参数与从 290 个正常骶骨得出的相同参数进行比较。所有带有附加关节的骶骨的参数均与正常骶骨的参数进行了统计学比较。
在 290 个正常骶骨中测量了 7 个线性尺寸和 5 个表面面积。测量了 30 个具有单侧附加关节面的骶骨和 12 个具有双侧附加关节面的骶骨，以测量相同的线性参数和表面面积。在正常和过渡骶骨中计算了 9 个来自这些测量的指数，并进行了统计学验证。
分析结果表明，与正常骶骨相比，带有附加关节的骶骨具有以下特征：其耳状面位于更高的位置；具有主要局限于两个上骶骨段的承重特征；关节面之间的距离较小；关节面冠状面与 S1 椎体后表面之间的距离较小；具有较小且更冠状的关节面；以及具有较小的体宽和体高。与正常骶骨相比，这些“过渡”骶骨的耳状面区域和 S1 体的上表面相似。双侧附加关节骶骨的线性尺寸小于单侧附加 L5-S1 关节的骶骨。
腰骶附加关节构成了交界处过渡变化的大部分。附加关节为单侧（9%）和双侧（3%），共有 12%的研究样本（n=332）表现出这种 L5-S1 过渡。腰骶假关节骶骨与正常骶骨相比具有不同的解剖特征。分析这些结构差异与正常变异可能有助于理解这些过渡部位的生物力学特性。分析这些骨骼内尺寸的相对比例可能有助于计划手术干预或预测这些骶骨异常承重模式。
