| Part? The anatomy and biomechanical study of sternoclavicular jointObjective:(1)To measure the anatomical data of the bony structures and ligaments around the sternoclavicular joint,observe its morphological characteristics,and provide anatomical parameters and theoretical basis for the development of anatomical locking plate for sternoclavicular joint dislocation or peripheral fractures.(2)To conduct a biomechanical test on the sternoclavicular joint and surrounding ligaments,and explore its biomechanical characteristics,provide biomechanical basis for the design of internal fixation plates used for sternoclavicular joint dislocation or peripheral fractures and provide biologic reference for the clinical operations.Methods:(1)Eight adult antiseptic and moist cadaver specimens(6 males and 2 females),with age of death at 32-56 years,46.5years on average were selected.The complete manubrium,bilateral clavicle and surrounding tissues of sternoclavicular joint were anatomically separated.The adherent muscles and unrelated soft tissues of the specimens were stripped to keep complete bilateral sternoclavicular joint,surrounding ligaments and joint capsule structure,and repair to bone-ligament-bone specimen models.The areas of manubrium articular surface and the medial clavicular articular surface of all specimens were measured by the ink pattern combined with grid counting method,and the results were statistical analyzed.Three-dimensional CT reconstruction was performed for all specimens,and the following anatomical parameters were measured by imaging and anatomical methods: the manubrium thickness was measured by reference to the method provided by Dong Jiachun et al,at the same time measuring the width of the sternal incisure,anteroposterior diameter and superoinferior diameter of bilateral clavicle proximal one-third,the angle between the bilateral clavicle and the manubrium in the coronal plane,the natural angle of the joints at the anatomical position.And then the statistical analysis of each group of data measured by the two methods.(2)The morphological features of the anterior and posterior sternoclavicular ligaments of the specimens in this group were observed,and the length,width and thickness were measured and analyzed statistically.(3)The left and right sternoclavicular joints of each specimen were randomly paired and grouped.For group A,the displacement and angle changes with the load of 0-10 N at the distal end of the clavicle before and after simple cutting of anterior sternoclavicular ligament were tested;for group B,the displacement and angle changes with the load of 0-10 N at the distal end of the clavicle before and after simple cutting of posterior sternoclavicular ligament were tested.With reference to the Spencer's biomechanical experimental study,the steps were as follows: specimens were fixed by special fixture in anatomical position,and a load test(constant loading 0-10 N,loading speed 2mm/min)was conducted at the anterior and posterior anatomical planes of the distal end of the clavicle.The experiment data were recorded in the terminal computer connected to the mechanical test machine,and a load-displacement curve was drawn.According to the displacement values,the forward and backward angles of sternoclavicular joint were calculated according to sinusoidal trigonometric function.The angles of joints and load-angle regression line slopes were compared between the two groups in the anterior and posterior directions load.Statistical analysis was performed using the SPSS19.0 statistical software and P<0.05 was considered statistically significant difference.Results:(1)In this group,the area of articular surface of manubrium(239.00 ±28.78mm2)was smaller than the area of medial articular surface of the clavicle(482.56 ± 44.89mm2),the difference was statistically significant(t =-40.105,P <0.001).The measured manubrium thickness,width of the sternal incisure,anteroposterior diameter and superoinferior diameter of bilateral clavicle proximal one-third,the angle between the bilateral clavicle and the manubrium in the coronal plane,the natural angle of the joints at the anatomical position showed no statistical difference between the gross specimen measurement method and CT method(P>0.05).(2)In this group,the length,width and thickness of the anterior sternoclavicular ligament were 17.56±1.94 mm,15.54±1.42 mm and 1.93±0.32 mm,and the length,width and thickness of the posterior sternoclavicular ligament were 17.21±1.86 mm,15.97±1.17 mm,2.07±0.29 mm respectively.The length of the anterior sternoclavicular ligament was slightly longer than that of the posterior ligament,with more relaxed morphological characteristics,but there was no significantly statistical difference in the length,width and thickness between them(P>0.05).(3)In the two groups of specimens,before and after cutting the sternoclavicular ligament,the angles of joints of forward and backward directions increased gradually with the increase in loads(0-10N),presenting a linear relationship.Before cutting the ligaments,when the loads were 2 N,4 N,6 N,8 N,10 N,the angle backwards of joint caused by loads in the forward direction was less than the angle of forwards of joints caused by loads in the backward direction,but only when the loads were 6 N,8 N,10 N,the difference between them was statistically significant(P<0.05).The slope of the regression line of load-angle for the loads in the forward direction was less than the slope of the regression line of load-angle for the loads in the backward direction,with statistical difference(F=31.413,P<0.001). When the ligaments were cut,when the loads in the forward direction in group A and group B were 2 N,4 N,6 N,8 N and 10 N,the backward angulation of joint in group A was less than that in group B,the difference was statistically significant(P < 0.05).And the slope of the load-angled regression line in group A was less than that in group B,with statistically significant difference between them(F=52.224,P<0.001).When the loads in the backward direction in group A and group B were 2N,4 N,6 N,8 N and 10 N,the forward angulation of joint in group A was greater than that in group B,the difference was statistically significant(P<0.05),and the slope of the load-angled regression line in group A was greater than that in group B,with statistically significant difference between them(F=12.503,P=0.008).Conclusion: There was no statistical difference in the results of the bony structures around the sternoclavicular joints measured by the anatomy and imageology methods.The CT three-dimensional reconstruction can not only make an accurate diagnosis of the dislocation of the sternoclavicular joint,but also can be used for the accurate measurement of the sternoclavicular joint and the surrounding bone structure,which is helpful to the choice of internal fixation scheme.The contact area between the articular surface of the medial clavicle and the articular surface of the manubrium is narrow,which determines the instability of the joint itself.The sternoclavicular ligament is extremely important for maintaining the joint stability.The biomechanical experimental study showed that,the anterior sternoclavicular ligament mainly plays a role of restricting joint forward angulation,and the posterior sternoclavicular ligament mainly plays a role of restricting joint backward angulation,the forward angulation of joint restriction effect of sternoclavicular ligament was weaker than that of the backward angulation,also because of the joint in the anatomical position of the natural forward angulation,so the sternoclavicular joint was prone to anterior dislocation.It is necessary to pay attention to the repair and reconstruction of sternoclavicular ligament when sternoclavicular joint dislocation or peripheral fractures are treated by operations.Part ? Development and biomechanical test of the anatomical locking plate of sternoclavicular jointObjective: To develop an anatomical locking plate in accordance with the anatomical characteristics of the sternoclavicular joint,which is reliable fixation and easy to operate,so as to provide an ideal internal fixation device for the treatment of sternoclavicular joint dislocation or peripheral fractures.Through comparative analysis of biochemical experiments,we conducted evaluation on the biomechanical properties of the anatomical locking plate of sternoclavicular joints for fixing the sternoclavicular joint dislocation,to provide basis for further clinical applications.Methods: According to the anatomical parameters and biomechanical properties of the specimens,the anatomical locking plate was designed and developed.The biomechanical comparison between the anatomical locking plate and the commonly used oblique "T" shaped locking plate was carried out.In this group,for the 8 sternoclavicular joint bone-ligament-bone structure specimens,sternoclavicular ligaments and joint capsules were completely cut with a scalpel to produce the models of sternoclavicular joint complete dislocation.The sternoclavicular joints on the left and right sides for each specimen were randomly paired and grouped: experiment group ALCP(anatomical locking plate fixation group),the control group OTLCP(oblique "T" shaped locking plate fixation group).The common stress mechanism of sternoclavicular joint dislocation was simulated on the universal biomaterial testing machine(Key Laboratory of biomechanics Sichuan University),and three biomechanical performing tests(clavicular distal load,sternoclavicular joint torsion,anti-pulling of steel plate manubrium part)were carried out respectively.The terminal computer of biomechanical testing machine could automatically collect experimental data and draw the stress-deformation curves.The analysis of experimental data was performed by SPSS19.0 statistical software and P<0.05 was considered statistically significant difference.Results:(1)According to the morphological characteristics of sternoclavicular joint and anatomical measurement parameters,the anatomical locking plate was developed and produced by the commissioned manufacturer with clinical medical equipment production license.It has been granted national utility model patent,design patent,while applying for invention patent.(2)In the distal clavicle load test,the load of the loading points was linearly related to the displacement.At the anatomical position,loads were added backwards perpendicular to the distal end of the clavicle;and at the maximum loading pressure 20 N,the displacement at the loading points of the two groups was different,8.455±0.981 mm in the ALCP group,and 10.163±1.379 mm in the OTLCP group,with statistical difference between the two groups(t=-3.012,P=0.020).At the anatomical position,loads were added upwards perpendicular to the distal end of the clavicle,and at the maximum loading pressure 20 N,the displacement at the loading points of the two groups was different,5.427±1.154 mm in the ALCP group and 6.393±1.040 mm in the OTLCP group,There was no statistical difference between the two groups(t=-1.459,P=0.188).The performance of anti-backwards deformation of clavicular end of the sternoclavicular joint in the ALCP group was stronger,while the performance of anti-upwards deformation of clavicular end of the sternoclavicular joint in the ALCP group was not significantly different from that of the OTLCP group.(3)In the sternoclavicular joint torsion experiment,the torque was linearly correlated with the twist angle within the range of the clockwise and counterclockwise twist angle 0~10° in the two groups of specimens,with the increase in the twist angle,the torque was increased gradually.When the clockwise twist angles in the two groups were 2 °,4 °,6 °,8 ° and10 °,the torques in the ALCP group were greater than those in the OTLCP group,showing statistically significant difference between them(P<0.05).When the anticlockwise twist angles in the two groups were 2 °,4 °,6 °,8 ° and 10 °,the torques in the ALCP group were greater than those in the OTLCP group,but only when the twist angles were 4 °,6 °,8 ° and 10 °,there was statistically significant difference between them(P<0.05).For the slope of regression line of torque-twist angle,i.e.torsional stiffness,the torsional stiffness in the ALCP group was 0.122 N.m/° and that in the OTLCP group was 0.083 N.m/° in the clockwise twist test,showing statistically significant difference between the two groups(F=67.824,P<0.001).In the anticlockwise twist test,the torsional stiffness in the ALCP group was 0.108 N.m/° and that in the OTLCP group was 0.078 N.m / °,showing statistically significant difference between the two groups(F=20.992,P=0.002).The anti-torsional deformation ability in the ALCP group(anatomical locking plate)was superior to that of the OTLCP group(oblique "T" locking plate).(4)The maximum pull-out resistance in the ALCP group was 225.24 ± 16.02N;the maximum pull-out resistance in the OTLCP group was 174.40 ±21.90 N,showing statistically significant difference between the two groups(t=5.785,P=0.001).The pull-out performance of fixed manubrium part in the ALCP group was superior.Conclusion: The anatomical locking plate for sternoclavicular joint developed in this topic is a new type of internal fixation device with three-dimensional fixation pattern designed according to the anatomical characteristics and biomechanical characteristics of sternoclavicular joint.Its fixation is reliable,and operation is simple,with small damage,high safety,with excellent biomechanical performance,it is conducive to early functional exercise.It provides a kind of ideal internal fixation device for the clinical treatment of sternoclavicular joint dislocation or peripheral fractures. |
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