Facet Dimensions, Orientation, and Symmetry at L5–S1 Junction in Lumbosacral Transitional States

Abstract

L5-S1 transitions possess altered facet morphology. These alterations are possibly related to low back pain situations.

Partial lumbosacral transitional vertebrae: 2 cases of unilateral sacralization

“…In each case, the skeletal anomaly limited ipsilateral flexion and coincided with ipsilateral muscular symptomatology. These findings seem to echo the arguments of Mahato, [22][23][24][25][26][27] who suggested that the biomechanical alterations brought on by the skeletal anomaly could contribute to the symptomatology. Conservative treatment directed at the involved muscle group in these cases resulted in decreases in symptom frequency and intensity, although it did not result in complete resolution in either case.…”

“…Some have argued that altered biomechanics of weight transmission across the L5-S1 articulation result because LSTV are associated with altered morphology at the joint. [22][23][24][25][26][27] These altered biomechanics are hypothesized to cause biomechanical compensations, which may partially explain the ipsilateral muscle hypertonicity noted in the current cases and by Brenner. 21 Other investigators 8 have suggested that LSTV increase the severity of the clinical picture, regardless of the causal relationship between LSTV and low back pain.…”

“…In case 1, improvements in pain levels and mobility were noted following a course of manual treatment. If, as Mahato [22][23][24][25][26][27] suggests, the decreased mobility at the L5/S1 junction resulted in biomechanical changes and altered weight distribution at this level, it is possible that these biomechanical changes increased the stress on the muscles in the region of the sacroiliac and lumbosacral junctions on the affected side, which resulted in the observed presentation. If that is the case, there is a possible role for conservative care in patients with this type of anomaly, not to relieve pressure on an impinged nerve but instead to address muscular alterations in the lumbopelvic musculature.…”

Facet Orientation and Tropism: Association With Accelerated Degeneration of Stabilizing Structures in Lower Lumbar Spine

“…Facet or zygapophyseal joints are true diarthrodial articulations situated on dorsolateral aspect of the spine 1 . Apart from resisting vertebral translation, those paired bony pillars add to spinal stability by supporting between 3% and 33% of compressive load, depending on current body position, and by facilitating or restricting movement in various spinal regions [2][3][4][5][6] .…”

“…ventral flexion and extension 4,9,10 . However, between L3 and S1 spinal level, facet orientation slightly changes to coronal thus facilitating more rotational movement, but also producing less mobility in the sagittal plane 1,[11][12][13][14] . Facet asymmetry or tropism is defined as a difference between the left and right facet angle, and although believed to be a normal feature of thoracic spine, in lumbar region more pronounced facet asymmetry is considered to be a possible cause of abnormal loading patterns that eventually may lead to pathologic conditions 1,12,[15][16][17] .…”