The Effect Of Different Humeral Axial Rotation To The Kinematics Of Shoulder Complex

Objective: Elevation of upper limbs is an important motion form of the shoulder joint,which have been widely used in the comparative study of shoulder kinematics in recent years.But there is no uniform standard for the motion.In this article,we hope to study the effect of axial rotation of the humerus on shoulder movement by clarifying the orientation of the palm or elbow in the process of the elevation of upper limbs.Methods: The Qualisys optical motion capture system was used to capture the behavior of 11 healthy male subjects.There were five kinds of actions: elevation with upward palms and downward palms in the plane of the scapula,as well as abduction with internal position,neutral position and external position of the upper arm.The collected motion data were imported into Visual 3D software to calculate the joint angle of the humerus,scapula,clavicle relative to the thoracic and the displacement of the humeral rotation center relative to the scapula.Data from the elevation of the right upper limb were extracted and analyzed statistically using SPSS 19.0.Results: In the scapula plane and from 20 degrees to 80 degrees of the elevation,the elevation of clavicle is 1.74 degrees greater,as well as the upward rotation is 5.67 degrees greater and the anterior tilting is 3.16 degrees greater of the scapula when comparing upward palms and downward palms.The maximum abduction angles of internal positon and neutral position of upper arm are 64.48 ± 5.22 degrees and 75.94 ± 5.92 degrees respectively.In the coronal plane and from 20 degrees to 60 degrees of the abduction,the retraction of clavicle is 10.94 degrees greater,as well as the external rotation is 9.03 degrees greater and the posterior tilting is 3.6 degrees greater of the scapula when comparing neutral position and internal position of upper arm.The retraction of clavicle is 3.95 degrees smaller,as well as the external rotation is 11.76 degrees smaller and the posterior tilting is 17.62 degrees smaller of the scapula when comparing neutral position and external position of upper arm.Conclusions: In the scapula plane,with different axial rotation of the humerus,the shoulder movement will be significantly different.In the coronal plane,if the external rotation of the humerus is limited in the abduction process,the abduction angle would be limited and lead to abnormalities of the scapula and clavicle movement.