Department of Anatomy, Sri Aurobindo Institute of Medical Sciences (SAIMS), Bhawrasala, Indore, Madhya Pradesh 452 010, India.
Spine J. 2010 Jul;10(7):610-5. doi: 10.1016/j.spinee.2010.04.012. Epub 2010 May 23.
Spines with sacralized fifth lumbar vertebrae are quite commonly encountered. Sacralizations represent a transitional state at lumbosacral junctions and are more susceptible to degenerative changes resulting from the altered load-bearing patterns at these regions.
The present study is an attempt to analyze the morphology of sacra with complete and partially fused (sacralized) L5 vertebrae and compare it with those observed in normal sacra.
STUDY DESIGN/SETTING: Measurements of dimensions and articular surface areas were recorded in samples bearing sacralized L5 vertebrae and in normal sacra. Relative contributions of dimensions and surface areas on the bone were worked out by calculating indices. Comparison with the normal sacra was expected to yield significant differences.
Means of all linear parameters and indices were compared between sacralized and normal samples and between the fused and unfused sides of unilaterally sacralized specimens. Unpaired Student t test was applied to assess the differences in the values.
Seven linear dimensions and five surface areas were measured in 330 sacra. Nine indices were formulated from them. Sixteen (4.8%) sacra presented with bilateral completely fused L5 vertebrae with the first sacral segments. Four (1.2%) showed unilateral complete unification of sacra with the transverse process of the L5 vertebra above. Parameters were compared between the normal and sacralized samples and also between the two varieties of sacralized specimen.
Sacra with fused L5 possessed significantly smaller heights than the normal ones if the fused L5 vertebra was excluded from the measurements. On inclusion of the L5, these sacra presented a grossly reduced distance between the zygapophyseal facets, a greater distance of the coronal plane of the facet joints from the posterior aspect of the L5, a narrower interauricular distance, slightly increased body width at the top of the sacrum (now L5), a comparable auricular surface area (with inclusion of the fusion of L5 transverse process at the lateral mass) to the normal ones, attenuated facet area, and occasionally, small intervertebral space between L5 and S1. The unilaterally fused variety exhibited overall smaller dimensions. None of these sacra showed accessory articulations at their ala. The auricular surfaces in these sacra spanned from mid-L5 to mid-S2 segments. The fusion of L5 increased the sacral height, width, and auricular surface. The auricular surfaces appeared to be situated "low-down" in context of the six (including L5) sacral segments.
Sacralization of L5 vertebra entails morphological alterations in the sacrum. The remnants of the original sacra in these specimens presented grossly diminished parameters. Sacralization of L5 possibly represents a structural and biomechanical adjustment to compensate for reduced joint interfaces associated with smaller sacra. It may correspond to one end of the transitional "spectrum," the other end being defined by lumbarization of the S1 sacral segment.
具有骶化第五腰椎的脊柱是相当常见的。骶化是腰骶关节的过渡状态，更容易受到这些区域的负重模式改变引起的退行性变化的影响。
本研究试图分析具有完整和部分融合（骶化）L5 椎体的骶骨的形态，并将其与正常骶骨进行比较。
研究设计/设置：在具有骶化 L5 椎体的样本和正常骶骨中记录了尺寸和关节表面面积的测量值。通过计算指数，得出了尺寸和表面积对骨骼的相对贡献。预计与正常骶骨的比较会产生显著差异。
比较骶化和正常样本之间以及单侧骶化标本中融合和未融合侧之间的所有线性参数和指数的平均值。应用未配对学生 t 检验评估值之间的差异。
在 330 个骶骨中测量了 7 个线性尺寸和 5 个表面面积。从它们中制定了 9 个指数。16 个（4.8%）骶骨具有双侧完全融合的 L5 椎体和第一个骶骨段。4 个（1.2%）表现为单侧完全融合的骶骨，L5 椎体的横突在上。比较了正常和骶化样本之间以及两种骶化标本之间的参数。
如果将融合的 L5 椎体从测量中排除，具有融合的 L5 椎体的骶骨的高度明显小于正常骶骨。如果包括 L5，这些骶骨的关节突关节面之间的距离明显减小，关节面冠状面距 L5 的后表面更远，耳状面距离更窄，骶骨顶部（现为 L5）的体宽略有增加，与正常的相比，耳状面面积（包括 L5 横突在侧块的融合）相当，关节面面积减小，偶尔 L5 和 S1 之间的椎间空间较小。单侧融合的种类表现出整体较小的尺寸。这些骶骨中没有任何一个表现出附件关节。在这些骶骨中，耳状面从 L5 中段延伸到 S2 中段。L5 的融合增加了骶骨的高度、宽度和耳状面。耳状面似乎位于六个（包括 L5）骶骨段的“低位”。
L5 椎体的骶化导致骶骨的形态发生改变。这些标本中原始骶骨的残迹呈现出明显减小的参数。L5 的骶化可能代表一种结构和生物力学的调整，以补偿与较小的骶骨相关的关节界面减少。它可能对应于过渡“谱”的一个末端，另一个末端由 S1 骶骨节段的腰椎化定义。
