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Home » Anatomy » Glenohumeral Instability: Understanding Definition, Causes, Symptoms, Classification

Glenohumeral Instability: Understanding Definition, Causes, Symptoms, Classification

Glenohumeral instability refers to an abnormal motion or displacement of the humeral head (ball) in relation to the glenoid (socket) of the shoulder joint. It disturbs normal functioning of shoulder joint and shoulder movement. It is a common condition characterized by a loss of stability and can result in recurrent shoulder dislocations or subluxations. In this article, we will explore the definition, causes, signs and symptoms, as well as the types and classification of glenohumeral instability.


Glenohumeral instability is a condition where the shoulder joint is prone to excessive translation or movement beyond its normal range. It can occur in both traumatic and atraumatic cases. Traumatic instability typically results from a significant force or injury, while atraumatic instability may occur due to inherent ligamentous laxity. Best guide available on glenohumeral instability.

Causes of glenohumeral instability

Several factors contribute to the development of glenohumeral instability, including:

  1. Traumatic Injury: A direct blow to the shoulder or a fall onto an outstretched arm can cause ligamentous or labral tears, leading to instability.
  2. Atraumatic Factors: Certain individuals may have inherent ligamentous laxity, shallow glenoid, or muscle imbalances that predispose them to instability.
  3. Repetitive Overhead Activities: Athletes or individuals who perform repetitive overhead motions, such as throwing or swimming, may develop instability due to repetitive stress on the shoulder joint.

Signs and Symptoms

The signs and symptoms of glenohumeral instability may include:

  1. Recurrent Shoulder Dislocations/Subluxations: The most significant indication of instability is the recurrent episodes of the shoulder joint moving out of its normal position, resulting in partial or complete dislocations.
  2. Shoulder Pain: Patients may experience pain during or after activities that stress the shoulder joint.
  3. Feeling of Shoulder “Giving Way”: Individuals with instability may report a sensation of the shoulder “giving way” or feeling unstable during certain movements.
  4. Limited Range of Motion: Instability can lead to a loss of shoulder range of motion, particularly in overhead positions or extreme ranges.
  5. Muscle Weakness: Patients may exhibit muscle weakness or imbalances around the shoulder joint, particularly in the rotator cuff muscles.

Types and Classification of gelonohumeral instability

Glenohumeral instability can be classified into different types based on the direction of instability. The most common types include:

  1. Anterior Instability: Anterior instability occurs when the humeral head moves forward or in front of the glenoid. The most prevalent type and often associated with a Bankart lesion, which involves a tear or detachment of the anterior-inferior labrum.
  2. Posterior Instability: Posterior instability involves the humeral head moving backward or toward the back of the glenoid. It is less common than anterior instability and can result from traumatic events, muscle imbalances, or repetitive throwing motions.
  3. Multidirectional Instability: Multidirectional instability refers to instability in multiple directions, including anterior, posterior, and inferior. It is often associated with generalized ligamentous laxity or atraumatic factors.
  4. Superior Instability: Superior instability is rare and involves upward displacement of the humeral head. It is commonly seen in overhead athletes or individuals with repetitive overhead activities.


Glenohumeral instability is a condition characterized by abnormal motion or displacement of the humeral head in relation to the glenoid. It can result from traumatic injury or atraumatic factors and presents with recurrent dislocations/subluxations, shoulder pain. Understanding the types and classification of Glenohumeral instability is essential for proper diagnosis and treatment.

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