Comparison of Shoulder Joint Functional Range of Motion in Overhead Athletes with and without Shoulder Impingement Syndrome: A cross sectional study

Background: The shoulder complex is known as one of the most mobile joints of body whose frequently use for overhead movements causes changes in the shoulder joint range of motion. Sub-acromial impingement syndrome (SIS) is one of the most common causes of shoulder pain affecting shoulder joint range of motion. The purpose of this study was to compare shoulder joint functional range of motion in overhead athletes with and without Shoulder impingement syndrome. Methods: The current research is a cross-sectional study, in which 63 male overhead athletes (30 subjects without impingement syndrome (age: 28.12±6.13 y/o) and 33 subjects with impingement syndrome (age: 26.83±4.81 y/o)) threw a handball ball three times, while seating on a chair. A 6-camera Vicon Motion Capture system recorded the markers placed on the upper limb and trunk during each of the throwing conditions. To evaluate the range of motion, a whole-body kinematic model was used in OpenSim software, with inverse kinematics used to obtain adequate joint angles (shoulder joint abduction as well as internal and external rotation). Results: The results indicated that the external rotation and abduction range of motion were greater in the athletes with shoulder impingement syndrome in comparison to those without impingement syndrome (P <0/001 and p= 0.04, respectively), while their internal rotation range of motion were more limited than that of athletes without impingement syndrome (p<0/001). Conclusion: Overhead athletes with impingement syndrome have greater glenohumeral external rotation and abduction and less internal rotation in the throwing shoulder in comparison to athletes without impingement syndrome. These findings can be used to screen and identify high-risk athletes and help the therapists to make more appropriate therapeutic plans in order to assist the injured athlete to return to sports as soon as possible.