Anatomical Measurement and Finite Element Study on Screw Channel Parameter in Percutaneous Fixation of Canulated Screw for Symphyseolysis

To provide anatomical basement for symphyseolysis treatment with percutaneous fixation of canulated screw, through anatomical measurement on pubic symphysis and the surrounding tissues, and conduct the finite element studies on screw channel parameters. 20 cases of normal pelvic specimens from embalmed adult cadavers were taken to measure the anatomical parameter of bony remark of pubic symphysis and the space between spermatic cord (round ligament of the uterus) and pubic tubercle. Anatomical measurement results showed that the narrowest diameter of the superior ramus of pubis was 9.127 +/- A 1.189 mm, distance between two pubic tubercles was 55.656 +/- A 3.780 mm, thickness of the upper pubic symphysis was 10.510 +/- A 0.814 mm, and distance between upper and lower pubic symphysis was 40.872 +/- A 1.211 mm; the distance between round ligament of the uterus and pubic tubercle was 4.408 +/- A 0.304 mm, and the distance between spermatic cord and pubic tubercle was 5.196 +/- A 0.251 mm. The angle between canulated screw guide pin and horizontal plane was 8.342 +/- A 2.152A degrees, the one between guide pin and coronal plane was 5.236 +/- A 1.612A degrees, and the distance from entry point to the outer edge of pubic tubercle was 10.023 +/- A 1.245 mm, which was measured by Mimics software. Percutaneous surgery at horizontal position was simulated on cadaver. And the screw was correctly placed in postoperative imaging examination. According to the anatomical data and finite element studies of screw channel parameter in percutaneous fixation of canulated screw for symphyseolysis, the method can improve the accuracy of screw placement and reduce complications.