Mechanism of Shoulder Impingement Syndrome
Shoulder impingement syndrome occurs when the subacromial space, which is the area between the acromion and the humerus, narrows during arm movement. This narrowing can lead to the impingement of a tendon, triggering an inflammatory response and resulting in shoulder impingement syndrome. Several mechanisms can contribute to the shrinkage of the subacromial space, including bone projections, thickening of the bones, injuries to the rotator cuff, and inflammation of the bursa.
Symptoms of Shoulder Impingement
Shoulder impingement typically presents with pain as the primary symptom, especially when lifting the arm overhead or reaching backward. The pain can originate from the shoulder itself, the top of the arm, or radiate down the outer side of the arm. It’s worth noting that some individuals may experience increased pain at night due to lying on the affected shoulder. Additionally, stiffness is a common complaint among individuals with shoulder impingement.
In certain cases, impingements can cause a clicking noise during specific movements. Athletes who have shoulder impingement may encounter difficulties in warming up and may experience pain in different areas depending on the demands of their sport. As the impingement progresses, weakness in the affected arm may become apparent.