[Classification of upper sacral segment based on continuous axial pelvic computed tomography scan].
OBJECTIVE
To introduce a classification system of upper sacral segment and its significance based on the continuous pelvic axial computed tomography scan.


METHODS
The whole pelvis 2.0 mm thick axial scan images of 127 cases were observed, the sacroiliac screw channel of S1 were measured, according to the size of the transverse screw channel the upper sacral segment were classified. Such as transverse screw channel existed and in at least 4 layer scan images its width was > 7.3 mm, it was defined as sacral segment of the normal type. Such as transverse screw channel existed and its maximum width was 7.3 mm or less on scanning level, it was defined as a transitional. Such as transverse channel did not exist, or its width on all scanning level was 0 mm or less, it was defined as dysplastic. Various cases,percentage, and the average of the transverse screw channel were calculated.


RESULTS
There were 58 normal (45.7%),42 transitional (33.1%), and 27 dysplastic (21.2%) upper sacral segments with an averaged width of the tansverse screw channel of 13.9 mm, 5.2 mm, and 0.9 mm, respectively. Each specimen could be defined as one of the three types of upper sacral segment without exceptions.


CONCLUSIONS
It is possible to insert a transverse iliosacral screw into a normal upper sacral segment when indicated because of the capacious transverse screw channel. The transverse iliosacral screw placement into the transitional and dysplastic upper sacral segments was contraindicated because of the limited or none transverse screw channel. The transitional upper sacral segment was superior to the dysplastic segment due to its starting point location restriction on the true lateral sacral view.
Hong-min
HM
Cai
Shu-tu
ST
Gao
Chuan-de
CD
Cheng
Xue-jian
XJ
Wu
Wu-chao
WC
Wang
Jin-cheng
JC
Tang
Wei-feng
WF
Duan
Chuan
C
Zhang
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015519:Bone Density; D001863:Bone Screws; D005260:Female; D005593:Fracture Fixation, Internal; D006801:Humans; D008297:Male; D008875:Middle Aged; D010384:Pelvic Bones / Q000000981:diagnostic imaging* / Q000601:surgery; D012447:Sacrum / Q000000981:diagnostic imaging* / Q000601:surgery; D014057:Tomography, X-Ray Computed; D055815:Young Adult