Biomechanical Comparion Of Between Three-dimensional And Traditional Locking Plate In Midshaft Clavicle Fracture

Objective: Clavicle fractures are common, especially in young, activemen. The incidence of clavicle fracture accounts for2%-12%of all adultfractures, accounts for44%-66%of broken shoulder. The mid-shaft claviclefracture account for80%of clavicle fractures. As the improvement of theeconomy and living standards, the injury mechanism of clavicle fracturechanged. The proportion of high falling injury, sports injury and trafficaccident injury increased significantly. The traditional view was that mostclavicle fractures can be treated conservatively, the effect is ideal. But inrecent years, studies of clavicle fractures increase significantly, the effect ofthe conservative treatment of clavicle fracture is not ideal. Nonunion,mal-union and residual symptoms of post-operation increase obviously. Insurgical treatment of clavicle fractures, the related complications ofpost-operation reduce significantly, the prognosis and function improvesobviously. Due to the change of damage mechanism, displaced obviously,comminuted, shortening clavicle fracture and open injury are more and more,the surgical treatment of clavicle fractures is increasing, the main types ofclavicle fractures are midshaft clavicle fracture. The types of plate includereconstruction plate, limited contact dynamic compression plate and lockingor anatomic locking plate, the argument of which type of plate is better hasbeen there. As the incremental improvements of internal fixation type andcontinuous improvement of surgical technique, the advantages of locking platehave become more and more obvious. Meanwhile the location of plate havesome argument, the common location include anterior position and superiorposition. In recent years, the biomechanical studies display superior plate isbetter. In recent years, researchs have put forward the concept ofthree-dimensional locked plate for midshaft clavicle fracture, but few scholars make biomechanical research. The experiment will be compared with theBiological and mechanical properties of the three-dimensional locking plateand the traditional position of locking plate of treatment of mid-shaft claviclefractures, will provide biomechanical basis for the position of plate of clinicaltreatment of mid-shaft clavicle fractures.Methods:8formalin-fixed human adult cadaveric specimens, for all men,aged29-49years old, the average age of38.8years. The acromioclavicularjoint and the sternoclavicular joint at the ends of the clavicle were brokenrespectively for complete clavicle specimens. By macroscopic observation andX-ray, osteoporosis, cancer, malformation, trauma and other diseases of theskeletal system of clavicle were removed. Only one clavicle fracture was ruledout,15specimens could take advantage of. A length of5mm bone defect wascreated with a band saw in all the same position of midshaft clavicle.:15specimens of clavicle, according to the similarity of length of clavicle,matched into5groups, each group accepted three processing methods. Thethree groups were: The group A were the locking plate on the superiorposition, the eight hole collarbone s-shaped locking plate after a simpleshaping, so that it is placed in the upper of clavicle, conform to the clavicleupper shape, at the same time, ensure the nail holes on both sides of fracturewere at least three screw holes. Three screws were placed on each side of thefracture in all constructs. The cortical screws were long enough to fully passthrough both cortices. The group B were the locking plate on the anteriorposition. The Locking plate was conformed to the shape of anterior position ofclavicle. The principle of screws were placed was the same with group A. Thegroup C was the three-dimensional locking plate fixation group, the platewithout shaping or after a simple shaping, a superior positioning at the lateralend and an anterior positioning at the medial end of fracture, ensured the nailholes on both sides of fracture were at least three screw holes, each side werealso implanted with three bicortical locking screw. Specimens were fixed onin self-made clamp with type Ⅱ denture base polymers, then installed thefixture and specimen in biomechanics machine, every specimen was in three-point bending test and torsional test.Three-point bending test: the sternal end of clavicle fixed with type Ⅱdenture base polymers, fixture and specimen were installed in a suitablelocation of biomechanics machine. The support was positioned at the medialsegment of fracture. The distance from the support to the fracture was1cm.The loading point was the clavicle distal superior surface, loading directionwas vertical downward. To eliminate specimen creep, the preliminaryexperiment was carried on before the experiment began, then carried on theexperiment and recorded the related the biomechanical data.Torsional test: Taking out of specimens from the fixture of thethree-point bending test, the sternal end and the acromial end of clavicle werefixed on the axial experimental fixture with type Ⅱ denture base polymers,then connected with the biomechanics machine. To eliminate specimen creep,the preliminary torsional experiment was carried on before the experimentbegan. Internal rotation was defined as a rotation of the lateral end in anterior,external rotation was defined as a rotation of the lateral end in posterior(internal rotation was positive rotation, external rotation was negative rotation),then carried on the internal rotational and external rotational experimentrespectively and recorded the related the biomechanical data.SPSS13.0statistical software was used for statistical analysis withrandomized block design, P <0.05was statistically significance.Results: In three-point bending experiment, the load pressure range is10N-80N, the three position plates have respectively a linear correlationbetween the displacement and load. With the increasing of load, thedisplacement increase gradually. Under the condition of maximum load,which was80N, the displacement was different in different plate position.Displacement of the anterior plate group(group B) was7.5308±0.1518mm,the Displacement of the superior plate group(group A) was6.206±0.1437mm,the displacement of the three-dimensional plate fixation group(group C) was6.7208±0.1188mm. The displacement of the superior plate group is minimum,The displacement of the anterior plate group is maximum. There are statistically significant difference between the three internal fixationgroups(p=0.000, p<0.05), the superior plate group is optimal, the anteriorplate group is worst.In internal Torsional experiment, the angular displacement was0to10o,the three position plates have respectively a linear correlation between thetorque and torsional angle. With increasing of torsional angle, torquegradually increased. Under the maximum torsional Angle, which was10°, thetorque was different in different plate position. The torque of the anterior plategroup(group B) was2.4396±0.15566Nm, The torque of the superior plategroup(group A) was2.4696±0.3223Nm, The torque of the three-dimensionalplate fixation group(group C) was3.0732±0.2572Nm. the torque of group C isgreater than group A and group B. There are statistically significant differencebetween group C and group A (p <0.05). There are statistically significantdifference between the three internal fixation groups(p=0.013, p<0.05), thethree-dimensional fixation group is optimal in internal torsional experiment.In external torsional experiment, the angular displacement was0to-10o,the three position plates have respectively a linear correlation between thetorque and torsional angle. With increasing of torsional angle, torquegradually increased. Under the maximum torsional Angle, which was-10°,the torque was different in different plate position. The torque of the anteriorplate group(group B) was2.3972±0.1090Nm, The torque of the superior plategroup(group A) was2.454±0.1332Nm, The torque of the three-dimensionalplate fixation group(group C) was3.0506±0.1431Nm. the torque of group C isgreater than group A and group B. There are statistically significant differencebetween group C and group A (p <0.05). There are statistically significantdifference between the three internal fixation groups(p=0.000, p<0.05), thethree-dimensional fixation group is optimal in external torsional experiment.Conclusions： In three-point bending test, The displacement of thesuperior plate group is minimum, The displacement of the anterior plate groupis maximum. The displacement of the three-dimensional plate fixation groupis in the middle. The three groups are statistically significant difference between each two groups. The biomechanical property of the superior plategroup is optimal, the anterior plate group is worst in three-point bending test.In internal torsional test, the torque of the three-dimensional platefixation group is bigger obviously than the anterior plate group and thesuperior plate group. There are statistically significant difference between thethree-dimensional plate fixation group and the anterior plate group. There arestatistically significant difference between the three-dimensional plate fixationgroup and the superior plate group. But There are no statistically significantdifference between the anterior plate group and the superior plate group. Thereare the same statistical results in the external torsional test. The biomechanicalproperty of the three-dimensional plate fixation group is optimal in torsionaltest.