• Physical Therapy Korea
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• v.31 no.1
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• pp.72-78
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• 2024

Background: Limitations of shoulder range of motion (ROM), particularly shoulder internal rotation (SIR), are commonly associated with musculoskeletal disorders in both the general population and athletes. The limitation can result in connective tissue lesions such as superior labrum tears and symptoms such as rotator cuff tears and shoulder impingement syndrome. Maintaining the center of rotation of the glenohumeral joint during SIR can be challenging due to the compensatory scapulothoracic movement and anterior displacement of the humeral head. Therefore, observing the path of the instantaneous center of rotation (PICR) using the olecranon as a marker during SIR may provide valuable insights into understanding the dynamics of the shoulder joint. Objects: The aim of the study was to compare the displacement of the olecranon to measure the rotation control of the humeral head during SIR in individuals with and without restricted SIR ROM. Methods: Twenty-four participants with and without restricted SIR ROM participated in this study. The displacement of olecranon was measured during the shoulder internal rotation control test (SIRCT) using a Kinovea (ver. 0.8.15, Kinovea), the 2-dimensional marker tracking analysis system. An independent t-test was used to compare the horizontal and vertical displacement of the olecranon marker between individuals with and without restricted SIR ROM. The statistical significance was set at p < 0.05. Results: Vertical displacement of the olecranon was significantly greater in the restricted SIR group than in the control group (p < 0.05). However, no significant difference was observed in the horizontal displacement of the olecranon (p > 0.05). Conclusion: The findings of this study indicated that individuals with restricted SIR ROM had significantly greater vertical displacement of the olecranon. The results suggest that the limitation of SIR ROM may lead to difficulty in rotation control of the humeral head.

• Physical Therapy Korea
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• v.19 no.4
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• pp.8-15
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• 2012

Posterior shoulder muscle tightness is frequently observed in shoulder impingement syndrome because tightness in the posterior portion of the shoulder muscles can cause anterior and superior translation of the humeral head in relation to the glenoid fossa. The purpose of this study was to determine the immediate effects of soft tissue massage on acromiohumeral distance (AHD), anterior translation of the humeral head, and glenohumeral (GH) range of motion (ROM) in subjects with posterior shoulder muscle tightness. Twenty-seven subjects with greater than $10^{\circ}$ difference in the range of GH horizontal adduction between right and left sides were recruited. The range of GH horizontal adduction and internal rotation were measured by a digital inclinometer. The AHD and anterior translation of the humeral head were measured using ultrasonography. A paired t-test was used to compare AHD, anterior translation of the humeral head, and the range of GH horizontal adduction and internal rotation before and after soft tissue massage. The results showed that AHD increased significantly (p<.05) and the anterior translation of humeral head decreased slightly, but not significantly (p=.40) after the soft tissue massage. Furthermore, the ROM of horizontal adduction and internal rotation in the GH joint increased significantly after the soft tissue massage (p<.05). These findings indicate that soft tissue massage on posterior shoulder muscle tightness is an effective method to increase AHD and ROM in the horizontal adduction and internal rotation of the GH joint.