What is internal shoulder impingement?
Internal shoulder impingement is a condition that typically affects athletes, particularly those involved in sports with overhead arm movements such as baseball, tennis, and swimming. It occurs when the rotator cuff tendons and the posterior labrum are pinched between the head of the posterior capsule of the humerus and the glenoid rim. This repetitive impingement can lead to fraying or partial tearing of the rotator cuff tendons, as well as labral tears, resulting in symptoms like posterior shoulder pain, stiffness, and weakness.
Symptoms
Symptomatic internal impingement manifests through various symptoms that can affect an individual's daily activities and athletic performance. Commonly, individuals experience deep posterior pain in the shoulder, which intensifies with overhead activities or throwing motions. This condition often leads to reduced strength in the affected shoulder, making it challenging to perform routine tasks or engage in sports. Since it results in greater tuberosity during abduction and external rotation, it may also lead to inflammation and potentially partial rotator cuff tears.
Additionally, those suffering from internal impingement may experience posterior shoulder tightness, making it difficult to fully rotate their shoulder or extend their arm above their head. A sensation of looseness or instability in the shoulder joint is also frequently reported, further complicating movement and exacerbating discomfort.
Causes
Internal shoulder impingement and shoulder problems are primarily caused by repetitive overhead activities that place significant stress on the shoulder joint. Common causes of internal impingement and shoulder injuries include:
- Repetitive motions, especially in sports that involve throwing or overhead activities, can lead to wear and tear on the shoulder.
- Incorrect technique in sports or physical activities can contribute to improper shoulder movement and subsequent impingement.
- Shoulder stiffness, tightness, or weakness can alter joint mechanics and increase the risk of impingement.
- Variations in the shoulder's anatomy, such as bone spurs or abnormal bone shapes, can contribute to impingement.










