Configuration of the posterior lumbar muscles regarding the study of the lumbosacral malformations

Purpose: A correlation between the shape of the three posterior lumbar muscles (Multifidus, Longissimus pars lumborum and Iliocostalis pars lumborum) and the vertebrae levels has been studied with regards to lumbosacral malformations and the extraforaminal approach (ELIF). Material and method: During a spine unit consultation, a series of 90 lumbar spines have been studied with X-ray and CT axial horizontal cross sections thanks to a special software. At every level, the ratio between the surface of the Multifidus and the global surface of the 3 posterior lumbar muscles was calculated. Among the 90 studied lumbar spines, 59 presented a normal bony frame while 31 were supposed to have a lumbosacral malformation. Results: For L5S1, L4L5, L3L4, L2L3 the normal ratio are respectively 95%, 51%, 34% and 18%. Any changes in these patterns may call forth a sacralization with two different forms, depending on the number (four or five) of the so-called “lumbar vertebrae”. Conclusion: The muscle patterns lead the clinician to study the lumbosacral malformation, and the surgeon to undergo the extraforaminal intermuscular discal surgery. Purpose: A correlation between the shape of the three posterior lumbar muscles (Multifidus, Longissimus pars lumborum and Iliocostalis pars lumborum) and the vertebrae levels has been studied with regards to lumbosacral malformations and the extraforaminal approach (ELIF). Material and method: During a spine unit consultation, a series of 90 lumbar spines have been studied with X-ray and CT axial horizontal cross sections thanks to a special software. At every level, the ratio between the surface of the Multifidus and the global surface of the 3 posterior lumbar muscles was calculated. Among the 90 studied lumbar spines, 59 presented a normal bony frame while 31 were supposed to have a lumbosacral malformation. Results: For L5S1, L4L5, L3L4, L2L3 the normal ratio are respectively 95%, 51%, 34% and 18%. Any changes in these patterns may call forth a sacralization with two different forms, depending on the number (four or five) of the so-called “lumbar vertebrae”. Conclusion: The muscle patterns lead the clinician to study the lumbosacral malformation, and the surgeon to undergo the extraforaminal intermuscular discal surgery.