Résumé
Objective To measure the sagittal anatomical parameters of the spine and pelvis based on EOS imaging system, and to evaluate the stress of the lower lumbar spine by finite element analysis (FEA). Methods A total of 44 subjects examined by EOS imaging system were included, including 11 sacral lumbar vertebra patients and 33 normal subjects. The sagittal plane parameters of lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT) and sacral slope (SS) were measured and compared in both groups. Pearson test was used to analyze the correlation between PI and LL in the two groups. At the same time, the finite element model of the lower lumbar vertebra was established. The stress condition of the lumbar spine model during forward bending, backward extension and left and right bending was evaluated by FEA method. Results The differences of PI, PT, SS and LL between the two groups were statistically significant (P<0.05). The correlation study found that there was a positive correlation between the two groups of subjects' PI and LL, including the lumbarization group (r = 0.69, P<0.05) and the normal group (r = 0.52, P<0.05). Under the conditions of forward bending, backward stretching, left bending and right bending, the bending moment of the model was 2 Nmm, and the stress concentration gradually decreased from bottom to top. The maximum stress concentration point was located at the lower articular process. Conclusion The physiological curvature and stress distribution of the lumbar spine in lumbarization population were different than normal, especially the stress concentration of the transitional intervertebral disc and articular process joint was obvious, and early degeneration of the spine was easy to occur.
Résumé
Labeling a transitional vertebra (lumbarization or sacralization) as "LSTV" helps in simplifying the reporting process but leads to mis-numbering and must be avoided, as reliable identification of vertebral levels is essential for surgical interventions and image guided interventions. Many parameters have been described to identify the vertebral level; however, there are contradictory results in literature regarding their usefulness. Objective: To determine the role of iliolumbar ligament (ILL) on MRI as an identifier of the L5 vertebra in cases of LSTV anomalies. Methods: 200 patients with confirmed L5 level (identified on MRI screening of whole spine) were included in the study. These were further divided into group I (159 patients), II (31 patients) and III (10 patients) consisting of normal spine, spine with sacralization and with lumbarization respectively. The level(s) of origin of the ILL was documented in all of them and analysis was done. Results: ILL was found bilaterally in all patients. All patients with normal lumbosacral junction had ILL arising from L5 bilaterally. Among sacralization group, 23 patients had ILL arising from L4, 2 patients had ILL arising from L5 and 6 patients had ILL arising from L4 on sacralized side and from L5 contralaterally. Among Lumbarization group 2 patients had ILL arising from S1, 5 patients had ILL arising from L5 and 3 patients had ILL arising from S1 on side of lumbarization and from L5 contralaterally. Conclusion: Our study demonstrated that ILL is not a reliable identifier of the L5 vertebra in the setting of LSTV anomalies. It rather identifies the lowest lumbar-type vertebral segment only.
Résumé
Introduction: Lumbosacral transitional vertebra (LSTV) is one of recognized morphological variant associatedwith back pain. As sacrum has very crucial role in weight transmission via sacroiliac joint, any change inmorphology of auricular surface of sacrum should have impact in morphology of lumbosacral region.Aim: To study relation between the variable extent of auricular surface in Sacrum and prevalence of LumbosacralTransitional Vertebra (LSTV) along with changes in morphological index.Materials and Methods: Present study was done by taking total 40 adult dry human sacra of both sexes whichwere collected from the Department of Anatomy at Himalayan Institute of Medical Sciences, SRHU, Dehradun. Allsacra were initially divided into two sacral groups of normal sacra and atypical sacra based on absence andpresence of any type of lumbosacral transitional vertebra (LSTV) respectively. Further each group subcategorizedinto three, namely A (normal sacra), B (high sacra) and C (low sacra) based on extend of auricular surface. Metrictraits like maximum auricular length, maximum sacral length, maximum sacral width and sacral index weremeasured and compared.Result: In this study sacra with higher type of auricular surface were found to be associated with more incidenceof sacralization whereas sacra with lower type of auricular surface were associated with lumbarization. Therewas significant difference noticed in mean sacral index of these two sacral groups. Sacral index in sacral groupwith LSTV (Mean 95.06) was found to be less on comparing with sacral group without LSTV (Mean 108.20).Increased mean maximum sacral length (mean 109.62) seen in sacral group with LSTV without significantchange in maximum sacral width (mean 103.75) which can be due to shift of weight transmission axis from lowersacral vertebrae to higher vertebrae.Conclusion: Variable extents of auricular surface of sacrum are associated with variant of lumbosacral transitionvertebra due to change in biomechanics of weight transmission. Thus this study may be helpful to clinicians topredict and treat root cause of LSTV associated back pain.
Résumé
Background: The sacrum is a large, triangular fused five sacral vertebrae and forms the postero-superior wall of the bony pelvis. Numerous anatomical variations of the sacrum have been reported including complete bilateral lumbarization of the first sacral vertebra in different race generates sacrum with three pairs of sacral foramina. There has never been reported among Gujarati population in Western India. These variations may be found in the living during radiological investigations for pain and neurological symptoms of patients or may be found during post mortem examination or during dissection of human body and osteology class for first M.B.B.S students. Objective: The study was designed to know the prevalence of sacrum with three pairs of sacral foramina among Gujarati population in Western India as there is paucity of available literature. Considering the variation, we conduct this study as a prelude to any type of experimental work in biomechanics, for diagnostic and therapeutic purposes in low back pain, spinal surgery and for interventional procedures like spinal anaesthesia and lumbar puncture. Materials and Methods: Observational study was carried out on 189 dry human sacra of known sex(115 male and 74 female) were studied from Department of Anatomy, B.J. Medical college Ahmedabad, Government Dental college Ahmedabad, Medical college Vadodara and Government Medical College, Surat in Gujarat. Morphological study was done on the sacrum. The sacra consisting of four vertebral segments were selected. The specimens were then carefully examined and recorded. Results: 189 dry human sacra were studied. Sacra with three pairs of sacral foramina were recorded. We founded 3 (1-Male, 2-Female) specimens of sacrum with three pairs of sacral foramina representing Bilateral complete lumbarization of first sacral vertebra. The degree of lumbarization varied: Bilateral complete lumbarization in 3 specimens and did not found Unilateral complete lumbarization specimen. Conclusion: The present study shows that the incidence of sacrum with three pairs of sacral foramina among Gujarati population in Western India is 1.58 %.The knowledge of this anatomical variation is of paramount importance to spinal surgeons, radiologists, forensic experts, morphologists and clinical anatomists.