Biomechanical Analysis And Clinical Fol Ow-up Of Pelvic Posterior Ring Fractures With Different Internal Fixation Methods

Objective:To compare the biomechanical properties of TightRope（?） system,Sacroiliac screw（IS）and tension band plate（TBP）in the treatment of C1 and C2 posterior pelvic ring fractures.To evaluate the biomechanical stability and clinical effects of minimally invasive percutaneous TightRope（?） system for the treatment of unstable pelvic posterior ring fractures.Materials and methods:This study consisted of a clinical retrospective study and a randomized controlled biomechanical trial.This clinical study retrospectively analyzed posterior pelvic ring fractures between June 2015 and May 2020.Eighteen patients with fracture AO types C1 and C2 underwent surgery using the TightRope（?） system to repair the ruptured posterior pelvic ring.All patients were followed up for at least 2 years and scored by Majeed scoring system.In the biomechanical tests,six embalmed adult pelvic specimens were used.In a randomized design,fractures were fixed using TightRope（?）,sacroiliac screw（IS）,and tension band plate（TBP）.The specimens were placed in a standing neutral position in a biomechanical testing machine,and a cyclic vertical load of up to 500 N was applied.The vertical displacement of the specimens and the ultimate load of each group were recorded by the testing machine.The vertical displacement and ultimate load are compared and analyzed by statistical method.Results:The mean operative time of TightRope（?） system for the treatment of pelvic posterior ring fractures was 31.94±4.58 minutes with no intraoperative complications.The mean follow-up was 38.89±8.72 months.Majeed scores were excellent in 14 cases and good in 4 cases.No serious clinical complications were observed in these patients.Four patients had delayed weight-bearing.In biomechanical experiments,TightRope（?） fixation significantly reduced the displacement of specimens compared with TBP fixation（P<0.05）when the load ranged from 300 to500 N.The displacement in the IS screw group was significantly lower than that in either the TBP or TightRope（?） group（P<0.05,）when the load ranged from 0 to 500 N.The ultimate load in IS screw group（1798±83.53 N）was significantly higher than that in TBP group（1352±74.41 N）and TightRope（?） group（1347±54.28 N）（P<0.0001）.However,there was no significant difference between the TightRope（?）and TBP groups（P=0.90）.Conclusion:Percutaneous posterior bi-iliac TightRope（?） system fixation of unstable pelvic fractures leads to good clinical and biomechanical effects,and is reliable and safe.