[Radiographic anatomical analysis of the pelvic Teepee view].

OBJECTIVES: To research radiographic anatomy of the main structure of the pelvic Teepee view, including its azimuth direction and view anatomy structure. METHODS: From June 2013 to June 2014 adult pelvic CT examination results were filtered, excluding skeletal deformities and pelvic osseous destruction caused by tumors, trauma, etc. The data of 2.0 mm contiguous CT scan of 9 adults' intact pelves was,selected and input into Mimics 10.01 involving 7 males and 2 females with an average age of (41.2±10.3) years old. Utilizing the software, the 3D CT reconstructions of the pelves were completed. Setting the transparency being high,the pelvic 3D reconstructions were manipulated from the pelvic anteroposterior view to the combined obturator oblique outlet view and fine-tuned till the regular Teepee-or teardrop-shaped appearance emerges. Cutting tools of the software were at the moment applied to separate the "Teepee" from the main pelvis for each reconstruction. Then the "Teepee" and the rest (main) part of the pelvis were displayed in different color to facilitate the analysis on the Teepee, iliac-oblique, and anteroposterior views. RESULTS: The "Teepee" started from the posterolateral aspect of the anterior inferior iliac spine and finished at the cortex between the posterior superior iliac spine and the posterior inferior iliac spine in a direction of being from caudal-anterior-lateral to cranial-posterior-medial. The radiographic anatomical composition of the "Teepee" contained one tip, one base,and two aspects. With the inner and outer iliac tables being the inner and outer aspects of the "Teepee", the tip is consequently formed by their intersection. The base is imaged from the cortex of the greater sciatic notch. The medial-inferior-posterior portion of the "Teepee" contains a small part of sacroiliac joint and its corresponding side of bone of the sacrum. CONCLUSIONS: The "Teepee" is a zone of ample osseous structures of the pelvis, aside from a small medial-inferior-posterior portion, the main zone of which can be accepted as a safe osseous zone for the anchor of implants stabilizing certain pelvic and acetabular fracture patterns. The Teepee view can be utilized as guidance for the safe percutaneous insertion of such implants.

[Classification of upper sacral segment based on continuous axial pelvic computed tomography scan].

OBJECTIVES: 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. CONCLUSION: 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.