Investigation of tendon damage rehabilitation parameters with elastic and viscoelastic behavior for continuous passive motion shoulder machine using Finite Element simulation

Shoulder joint is the most important and complicated joints in muscular-skeletal of human body therefore increasing mobility in the Gelenohumeral joint is one of main instability factor in order to enhance injury in comparison with other joints. Since stability of the joint almost depends on soft tissue (muscles and tendon) around that, therefore an investigation of Rotator Cuff tendon is surely considerable. As far as we know bones move by importing special force not only to muscle but also to tendon. All injuries especially rupture and variation of viscoelasticity properties such as age changes lead to decreasing degrees of shoulder joint freedom. In this paper we try to use Finite Element Model (FEM) to calculate maximum critical stress and strain according to biomechanical behavior of Rotator Cuff tendon. Age and gender alternation could effect on biomechanical properties of tendon in spite of the fact that unfortunately some researchers have ignored these variations. Also some of them are using of elastic tendon behavior instead of using viscoelastic behavior which is important indicator for tendon that it causes different behavior between both of them. Taking care of injured tendon and rehabilitation of the Rotator Cuff tendon by using continues passive motion (CPM) which is used for disable persons is another factor to study the Glenohumeral joint and biomechanical properties of it. Data obtained in this paper can improve frequency of shoulder joint just abduction movement when designing CPM by using biomechanical behavior of the tendon. Consequently before we make this complex system, all parameters regarding the mechanical tendon should be investigated so that we have a reliable instrument for an increased domain movement of shoulder joint.

Keywords:

shoulder joint , Rotator Cuff tendon , Viscoelasticity , Biomechanics , FEM