[Three-axis displacement classification of pelvic fracture and its reduction principles].

Objective: Based on images of pelvic CT three-dimensional reconstruction, to establish three-dimensional coordinate system of pelvis and investigate the three-axis displacement classification of pelvic fracture and its reduction principles.

Methods: Between June 2015 and May 2016, 21 cases of normal pelvic CT data were included in the study, and the mean pelvic three-dimensional model was established. The pelvic three-dimensional axis was established by defining the origin as the midpoint of the anterior superior iliac spine. Based on this coordinate system, a three-axis displacement classification of pelvic fracture were built. To assess the clinical guidance value of the three-axis classification, 55 cases (29 males and 26 females, aged 11-66 years with an average of 35.6 years) of pelvic fractures were analyzed by this classification, and replaced and fixed according to the principles of the reverse reduction.

Results: According to the theory of three-axis, pelvic fractures were divided into x-axis positive displacement/negative displacement, positive rotation/negative rotation; y-axis positive displacement/negative displacement, positive rotation/negative rotation; z-axis positive displacement/negative displacement, positive rotation/negative rotation. The average incision of included patients with pelvic fractures was 7.1 cm. The average reduction time was 12.2 minutes and the average radiation time was 55.3 s. The average time of screw implantation was 27.2 minutes. Postoperative pelvic X-ray films or three-dimensional CT showed all pelvic fracture was reducted well and the screw or plate was implanted correctly. The average intraoperative blood loss was 96.5 mL, the average operation time was 2.1 hours, and the average hospitalization time was 18.7 days. All patients were followed up 6-53 months (mean, 16.7 months). At last follow-up, according to Matta standard by pelvic radiography evaluation, there were excellent in 39 cases, good in 13 cases, and fair in 3 cases, the excellent and good rate was 94.55%.

Conclusion: Based on three-dimensional coordinate system, three-axis displacement classification of pelvic fracture can illustrate the displacement mode of patient simply and accurately, and can also guide the intraoperative reduction precisely.