Quantitative anatomical study of percutaneous cannulated lag screw fixation for treatment of symphysis pubis diastasis / 中华创伤杂志

ABSTRACT

Objective To perform anatomic study on percutaneous cannulated-screw fixation of symphysis pubis diastasis in human cadaveric pelvic specimens so as to provide a basis for clinical practice of the technique.Methods Fifteen adult pelvic cadaveric specimens were dissected to expose pubic symphysis,peripheral major vascular nerve,spermatic cord and round ligament of the uterus.Thickness of pubic symphysis and distance between the outer edge of pubic tubercle and spermatic funicle or round ligament of uterus were measured respectively.Distances were measured respectively from entry and exit points to the above-mentioned structures in the direction of guide pin.Entry depth and angles of guide pin with the coronal plane and cross section of the human body were measured.Surgery was simulated to prove the surgery effect through post-surgery filming and CT.Results Thickness of symphysis pubis was gradually reduced from up to down.Pubic tubercle part was the most thick and it could accommodate a 7.3 mm cannulated-screw.Entry and exit points of cannulated-screw were in certain distances with the important nervusvascularis and spematicfunicle (or round ligament of uterus) in the periphery,which were invulnerable to damages in the process of surgery.Proper lengths of cannulated screws were (73.6 ± 1.3) mm for males and (72.4 ± 1.7)mm for females (t =3.146,P ＜ 0.05).Screw thread was completely embedded in pubic tubercle.Angles of guide pin with coronal plane and cross section of human body were (7.3 ± 1.1) °and (6.4 ± 1.0) ° for males (6.9 ± 1.5) ° and (6.1 ± 0.6) ° for females.Radiography and CT findings confirmed that all pin tracks were in the bone substances with angle and length of screws staying within the scope of experiment.Conclusion Percutaneous cannulated screw fixation is reliable and safe for symphysis pubis diastasis.