title: Iliac hyperdense line: a new radiographic sign of gluteal muscle contracture.
abstract: BACKGROUND
  A hyperdense line on the ilium that runs roughly parallel to the sacroiliac joint (we called it "iliac hyperdense line sign") was frequently observed on pelvic radiographs of patients with gluteal muscle contracture (GMC). A literature search revealed no description of this sign.
  
  
  OBJECTIVE
  To determine the relationship between the iliac hyperdense line sign and GMC and to explore how this sign is formed.
  
  
  METHODS
  Pelvic plain films of 103 cases of GMC and those of 200 control individuals were reviewed for the presence or absence of the iliac hyperdense line sign. Pelvic CT scans in 8 of 103 cases and 13 of 200 controls were analyzed with relation to the plain films.
  
  
  RESULTS
  The iliac hyperdense line sign was visualized in 85 of 103 (82.5%) cases of GMC and none of the 200 controls. In the GMC group, pelvic CT scans showed a deformity of the posterior ilium. The lateral cortex of the posterior ilium took on a partly or completely anteroposterior course, while in the control group the course appeared as an oblique orientation from posteromedial to anterolateral.
  
  
  CONCLUSIONS
  The iliac hyperdense line on pelvic plain film can be used as a radiographic sign to suggest a diagnosis of GMC. This sign might be a result of the long and persistent pulling effect of the contracted gluteus maximus muscle, which deforms the lateral cortex of the posterior ilium from an oblique course to an anteroposterior course tangential to the X-ray beam.
authors.affiliation: Department of Radiology, Children's Hospital, Chongqing Medical University, Chongqing 400014, China. cjh710506@tom.com
authors.forename: Jin-Hua
authors.initials: JH
authors.lastname: Cai
authors.forename: Lan-Feng
authors.initials: LF
authors.lastname: Gan
authors.forename: He-Lin
authors.initials: HL
authors.lastname: Zheng
authors.forename: Hao
authors.initials: H
authors.lastname: Li
mesh_terms: D000293:Adolescent; D000328:Adult; D000900:Anti-Bacterial Agents / Q000008:administration & dosage; D002081:Buttocks / Q000000981:diagnostic imaging*; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D003286:Contracture / Q000000981:diagnostic imaging* / Q000209:etiology; D005260:Female; D005355:Fibrosis; D006801:Humans; D007085:Ilium / Q000000981:diagnostic imaging*; D007273:Injections, Intramuscular / Q000009:adverse effects; D008297:Male; D018482:Muscle, Skeletal / Q000473:pathology; D009133:Muscular Atrophy / Q000000981:diagnostic imaging; D010388:Pelvis / Q000000981:diagnostic imaging; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed
chemical_list: D000900:Anti-Bacterial Agents