| Objective To compare the stability of the tension band fixation in different directions(upward force along Supraspinatus muscle, backward force along the infraspinatus andteres minor muscles).through the biomechanical test of greater tuberosity fracture bytension band fixation,aiming at providing biomechanical basis for the clinical treatmentof the humeral greater tuberosity by the method of the tension band fixation.Methods The12humerus model(The same material(PVC)the same manufacturer,unifiedproduction batch)were divided into A and B groups(6in each group).The canvas waremade with the same specifications with2.4cm×10cm,The canvas articles were sticked togreater tuberosity of humeral with502glue in the right position.One end of canvas stickto greater tuberosity was3cm long,the other end of canvas used to connect tobiomechanical testing machine is2cm,the free part of canvas was5cm.The canvas ingroup A were used to imitate the supraspinatus muscle tensi and the ones in group B wereto imitate the infraspinatus and teres minor tension,then the model was established. Thefracture were fixed by2.0Kirschner and Romer wire with the same manufacturer andbatch.A straight upward force was used in group A to imitate to pull supraspinatusmuscle to established force-displacement curve on supraspinatus muscle.the outcomeswere classified into load to3mm yield point,load to5mm yield point,and load to failuresubgroup.A straight backward force was used in group B to imitate to full infraspinatusmuscle and teres minor muscle to established force-displacement curve on thesemuscle,the outcomes were classified into3set group as the same as the group A.Load tofailure was described that load suddenly decreased in the process of biomechanical loador force-displacement curve dropped or interrupted,the cause also included that theRomer wire was broken,the Kirchner was pulled out,the displacement was beyond1cm orangle was beyond45°.Record the value of each case under different condition.Make atable and analyze the results of experiment Each set of data were analyzed by statisticalsoftware.Result The force in group A and group B are280.17±11.41N,151.17±9.39N,P<0.05.When the displacement of the greater tuberosity was3mm, respectively There was asignificant difference between the group A and group B.The force in group A was greaterthan that in group B significantly.Samely,at the5mm displacement the group A and the group B were477.17±14.86N,288.83±7.63N,respectively P<0.05.the group A showedgreater significant difference than group B.For the load to failure,the group A and thegroup B were689.00±20.93N,580.50±23.53N,(P<0.05).the difference was significantbetween group A and group B,In group A,the Kirchners were pulled out in two cases,theRomer wire breakage occurred in two case,displacement beyond1cm occurred in twocase.In group B;the Romer wire breakage occurred in one case,displacement beyond1cmoccurred in two case and the angle beyond45°occurred in three case.Conclusion This biomechanical study in both3mm and5mm displacement during theexperiment,or in the process of testing load to failure, Group A compared with group Bshowed obvious biomechanical advantages,Tensile strength of tension band fixation inthe vertical upward direction is greater than that in the vertical backward.Tension bandtechnique for the treatment of humerus fractures of the greater tuberosity need more andfurther biomechanics research.In terms of the fixed intensity, or the cost of tension bandhas the advantages of its clinical application,but using this fixation, we must takeappropriate protective measures(Such as forearm condole belt protection), and also payattention to rehabilitation after surgery. |
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