title: Conflicting calculations of pelvic incidence and pelvic tilt secondary to transitional lumbosacral anatomy (lumbarization of S-1): case report.
abstract: Advancements in the understanding of adult spinal deformity have led to a greater awareness of the role of the pelvis in maintaining sagittal balance and alignment. Pelvic incidence has emerged as a key radiographic measure and should closely match lumbar lordosis. As proper measurement of the pelvic incidence requires accurate identification of the S-1 endplate, lumbosacral transitional anatomy may lead to errors. The purpose of this study is to demonstrate how lumbosacral transitional anatomy may lead to errors in the measurement of pelvic parameters. The current case highlights one of the potential complications that can be avoided with awareness. The authors report the case of a 61-year-old man who had undergone prior lumbar surgeries and then presented with symptomatic lumbar stenosis and sagittal malalignment. Radiographs showed a lumbarized S-1. Prior numbering of the segments in previous surgical and radiology reports led to a pelvic incidence calculation of 61°. Corrected numbering of the segments using the lumbarized S-1 endplate led to a pelvic incidence calculation of 48°. Without recognition of the lumbosacral anatomy, overcorrection of the lumbar lordosis might have led to negative sagittal balance and the propensity to develop proximal junction failure. This case illustrates that improper identification of lumbosacral transitional anatomy may lead to errors that could affect clinical outcome. Awareness of this potential error may help improve patient outcomes.
authors: Norton Leatherman Spine Center, Louisville, Kentucky.
authors: Charles H
authors: CH
authors: Crawford
authors: Norton Leatherman Spine Center, Louisville, Kentucky.
authors: Steven D
authors: SD
authors: Glassman
authors: Norton Leatherman Spine Center, Louisville, Kentucky.
authors: Jeffrey L
authors: JL
authors: Gum
authors: Norton Leatherman Spine Center, Louisville, Kentucky.
authors: Leah Y
authors: LY
authors: Carreon
mesh_terms: D001416:Back Pain / Q000000981:diagnostic imaging / Q000209:etiology / Q000473:pathology / Q000601:surgery; D006801:Humans; D007796:Laminectomy / Q000009:adverse effects; D008141:Lordosis / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D010388:Pelvis / Q000000981:diagnostic imaging / Q000473:pathology*; D015203:Reproducibility of Results; D012447:Sacrum / Q000000981:diagnostic imaging / Q000473:pathology*; D012720:Severity of Illness Index; D013123:Spinal Fusion / Q000009:adverse effects; D013130:Spinal Stenosis / Q000000981:diagnostic imaging / Q000209:etiology / Q000473:pathology / Q000601:surgery
keywords: anatomy; lumbar; lumbosacral radiographic measurements; pelvic parameters; sagittal alignment