The Mechanical Test And Clinical Application Of The Nail-rod System In The Pelvic Horizontal Rotation Unstable Injury Model

Objective Based on the screw rod system,reconstruction plate,external fixation in the horizontal rotating unstable pelvic injury model of mechanical test,comparing the three fixation of pelvic biomechanical stability,provide a theoretical basis for clinical treatment.Methods Seven normal adult pelvic specimens,along with their spines intact from the fifth lumbar vertebra to the sacrum,the proximal 20 centimeters of both femurs,retaining the intact of anterior sacroiliac ligaments,posterior sacroiliac ligaments,sacrotuberous ligaments,sacrospinous ligaments,and hip joints.The pelvic were loaded vertically in the AGX biomechanics testing machine with a standing posture.The displacements of the symphysis pubis were recorded while the loads were applied through the L5 body to a maximum of approximately 500 N.Testing was first performed on intact pelvic and then the model of horizontal rotating unstable injury of the pelvis(Tile B1)which the symphysis pubis,unilateral anterior sacroiliac joint,and ipsilateral sacropinous and sacrotuberous ligaments were cut.A Tile B1 injury was simulate,d on each pelvis.The following fixation were then applied:screw rod system fixed to supra-acetabular region of the anterior,four-hole 3.5 mm reconstruction plate fixed to the superior symphysis pubis with 4 cortical screws,and the pelvic external fixator fixed to anteriorsuperior.Results This study showed that three fixations could significantly decrease displacement of symphysis pubis and partly restore the biomechanical stability of pelvic.Under the same condition,the displacement of symphysis pubis of intact pevic was(0.121 ± 0.025)mm,the displacement of symphysis pubis of Tile B1 was(4.512 ±0.391)mm,the displacement of symphysis pubis with pedicle screw rod system was(0.656±0.103)mm,the displacement of symphysis pubis with reconstruction plate was(0.358±0.051)mm,and the displacement of symphysis pubis of pelvic external fixator was(1.512±0.101)mm.There were differences(P<0.05)between three fixations.Conclusion Biomechanics testing in screw rod system,reconstruction plate,pelvic external fixation fixed to model of rotating unstable pelvic injury(TileB1),three fixation can be significantly reduce the displacement of symphysis pubis,can effectively restore the biomechanics stability of the anterior ring of pelvis.Biomechanics stability fixed by reconstruction plate was the best,fixed by screw rod system was the better,fixed by pelvic external fixator was the worst.Objective To investigate the feasibility of scrow rod system in treatment of the anterior pelvic ring injury and evaluate its therapeutic effects,and to guide clinical application.Methods From September 2010 to January 2013,10 patients with closed pelvic injury were treated with screw rod system.There were six males and four females,at age range of 14 ～ 45 years(average 31 years).All patients had closed anterior pelvic ring injmy.2 cases of Tile type Bl,2 cases of Tile type B3,6 cases of Tile type C2.Evaluate therapeutic effects according to Majeed of pelvic injury function assessment.Results The operation of the anterior pelvic ring injury with screw rod system lasted for average 35 minutes(range,25 ～ 60 minutes).9 patients were followed up for average 12 months(range,4 ～20 months),which showed that all patients got satisfactory reductions and that the fractures were healed,with average period of11.5 weeks(range,9～15 weeks).There occurred no infections,failures of internal fixations or nerve injuries.According to Majeed of pelvic injury function assessment,the result was excellent in two patients and good in seven.Conclusion under master of the surgical indications,scrow rod system treating the anterior pelvic ring injury take advantages of minor trauma,reliable fixation,short operation time,good curative results and few complications.