Analyzing and assessment of different muscle groups in shoulder joint with finite element method

In glenohumeral joint, critical strains and tears may be stemmed from excessive utilization of different muscle groups such as rotator cuff, deltoid, or from the injuries related to accidents or acute disorders. To investigating the effects of the alteration of these muscle groups in shoulder capsule, data of right humerus magnetic resonance imaging (MRI), which are belonged to a 31 years healty male donor have been obtained. Three dimensional solid model of right humerus was obtained with ITK – SNAP medical imaging program by benefiting from the MRIs. The constituted model was imported into SolidWorks 2019 and the assembled finite element model was imported into Ansys 19.3. After this stage, force directions of rotator cuff and deltoid middle muscles were determined according to the coordinates of humerus and scapula. In the sequel, to obtain the time – related force values in external rotasyon, a jeneric model was utilized in OpenSim 4.1 program and static optimisation analyses were performed for 100, 50 and 0 percent infraspinatus activities in 11 degree abduction and 60 degree external rotation. Obtained variable muscle force values were integrated to the finite element humerus model. Transient analyses of the finite element model were fulfilled considering full, half power and the tear conditions of infraspinatus muscle. Related to the power losses in infraspinatus, it has been investigated how other rotator cuff muscles and deltoid middle muscle have been affacted and the effects of these force variations to labrum and glenoid cartilage in the shoulder joint.