We hypothesised that the anterior and posterior
walls of the body of the first sacral vertebra could be visualised with
two different angles of inlet view, owing to the conical shape of
the sacrum. Six dry male cadavers with complete pelvic rings and
eight dry sacrums with K-wires were used to study the effect of
canting (angling the C-arm) the fluoroscope towards the head in
5° increments from 10° to 55°. Fluoroscopic images were taken in
each position. Anterior and posterior angles of inclination were
measured between the upper sacrum and the vertical line on the lateral
view. Three authors separately selected the clearest image for overlapping
anterior cortices and the upper sacral canal in the cadaveric models.
The dry bone and K-wire models were scored by the authors, being
sure to check whether the
K-wire was in or out. In the dry bone models the mean score of the relevant inlet position
of the anterior or posterior inclination was 8.875 (standard deviation
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