Iliac hyperdense line: a new radiographic sign of gluteal muscle contracture.
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.
Cai
Jin-Hua
JH
Department of Radiology, Children's Hospital, Chongqing Medical University, Chongqing 400014, China. cjh710506@tom.com
Gan
Lan-Feng
LF
Zheng
He-Lin
HL
Li
Hao
H
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
D000900:Anti-Bacterial Agents