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Disc spaces, vertebral dimensions, and angle values at the lumbar region: a radioanatomical perspective in spines with L5-S1 transitions: clinical article.

OBJECT
Low-back pain (LBP) has been associated with lumbar spines of normal morphology as well as those with L5-S1 "transitional" vertebrae. It is hard to find literature that quantifies the overall morphological changes in lumbar spines as related to transitional states. The object of this study was to investigate lumbar spine changes resulting from the presence of these transitional states.


METHODS
The author quantified dimensions and angles and statistically compared the morphology of lumbar spines with or without L5-S1 transitions in the context of LBP. Anteroposterior and lateral radiographs were obtained from 50 patients suffering from LBP without transitional anomalies at the L5-S1 junction. These radiographs were compared with anteroposterior and lateral radiographs from patients suffering from LBP with L5-S1 transitional states involving accessory L5-S1 articulations, and with anteroposterior and lateral radiographs from patients with L5-S1 unilateral or bilateral fusions. Twelve linear dimensions from the anteroposterior views and 8 angles from the lateral radiographs were measured.


RESULTS
The mean values of linear dimensions differed in 1) disc heights, 2) vertebral heights and widths, 3) pedicles and interpedicular distances, 4) angle values, and 5) overall configuration of the lumbar curvatures.


CONCLUSIONS
The L5-S1 accessory articulations led to increased lordotic curves, L-5 vertebral heights, and pedicle and angular dimensions. The L5-S1 fusions were related to smaller disc heights at all spaces, short and wide L-5 pedicles, taller and less wide transverse processes, and overall straighter spines with the least measures for all lumbar angles. Dimensional differences provided in this study may help in placing instrumentation at the lumbar vertebrae and working on intervertebral disc replacements in spines with specific L5-S1 transitional anomalies.