Exploration and Analysis of Baliao Points Location by Proportional Bone Measurement on the Basis of CT Three-Dimensional Reconstruction

OBJECTIVE To explore Baliao points location method by proportional bone measurement and provide reference for clinic and teaching. METHODS 100 prone pelvic CT images performed from January 2016 to June in Nanjing Hospital Affiliated to Nanjing Medical University was analyzed retrospectively. Three-D images were established by continuous cross section scanning with 5mm layer thickness. The distances of L5 spinous process to coccyx tip， L5 spinous process to sacral hiatus， L5 spinous process to the posterior superior iliac spine， L5 spinous process to Baliao points， posterior midline to Baliao points and posterior midline to the posterior superior iliac spine were measured. RESULTS ①Four sacral bone measurements were obtained through establishing sacral bone scale， they were about 6 cun from L5 spinous process to coccyx tip， 3 cun from L5 spinous process to sacral hiatus， about 1 cun from L5 spinous process to the posterior superior iliac spine vertically， about 2 cun from posterior superior iliac spine to posterior midline. ②Baliao points could be located as follows on the basis of sacral bone scale: Shangliao (BL 31) was located in 1.1 cun next to posterior midline， 1 cun below L5 spinous process; Ciliao (BL 32) was located in 1 cun next to posterior midline， 1.7 cun below L5 spinous process; Zhongliao (BL 33) was located in 0.9 cun next to posterior midline， 2.5 cun below L5 spinous process; Xialiao (BL 34) was located in 0.9 cun next to posterior midline， 3.5 cun below L5 spinous process. ③Baliao points could be located as follows according to body surface signs of partes sacralis: from the longitudinal distance of partes sacralis， Shangliao (BL 31) was parallel with the posterior superior iliac spine; Ciliao (BL 32) was parallel with the midpoint of L5 spinous process and sacral hiatus; Zhongliao (BL 33) was parallel with the midpoint of L5 spinous process and coccygeal tip; Xialiao (BL 34) was parallel with the sacral hiatu. From the transverse distance of partes sacralis， Ciliao (BL 32) was located in the midpoint of the posterior superior iliac spine and posterior midline. Baliao points were lined as reversal "八"， and the angle between the connection of Baliao points and the posterior midline was 25 degrees. But the body surface signs and bone standard could only provide the most likely location for Baliao， so Baliao points location could be confirmed through combining point identification and touching the hollow. CONCLUSIONS On the basis of body surface signs， transforming "measurement" to "standard"， and locating Baliao points according to proportional relationship and bone degree， which are worthy of clinical reference.