Influence of the sagittal anatomy of the pelvis on the intercrestal line position.
OBJECTIVE
The line joining the two iliac crests is classically regarded as the anatomical landmark determining the inter-vertebral space L4-L5 for the spinal punctures. Its variability has been reported but never related to predictive clinical anatomic factors identifying patients groups in which there is increased risk of miscalculation of the spinal level.


METHODS
Two sagittal pelvic anatomical angles, called 'pelvic incidence' and 'pelvic lordosis' were measured on lateral X-rays of the pelvis of 132 normal individuals and 49 spondylolysis patients. The values were compared with the sagittal projection of the intercrestal line on the disco-vertebral lumbar structures.


RESULTS
A strict relation was observed between this projection of the intercrestal line and the sagittal pelvic anatomical angles. The greater the pelvic incidence, the higher the intercrestal line was projected, all the more in patients with spondylolysis with a listhesis or a disc narrowing.


CONCLUSIONS
The relation between the pelvic sagittal angles and the intercrestal line projection explains the variability described for this anatomical landmark. It implies precautions minimizing neurological risk in the case of a puncture carried out more cranially than expected, particularly for high values of pelvic incidence occurring in spinal pathologies such as spondylolysis, in the elderly or in the obese patients. In these cases, we recommend the use of spinal imaging during the procedure to assist selection of the desired insertion level.
Horduna
M
M
University Hospital of Amiens, Department of Anaesthesia, Amiens, France.
Legaye
J
J
D000293:Adolescent; D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008141:Lordosis / Q000000981:diagnostic imaging; D008297:Male; D008488:Medical Illustration; D008875:Middle Aged; D010384:Pelvic Bones / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D011859:Radiography; D012016:Reference Values; D012307:Risk Factors; D012720:Severity of Illness Index; D013168:Spondylolisthesis / Q000000981:diagnostic imaging; D013169:Spondylolysis / Q000000981:diagnostic imaging*