Shoulder Dislocations (Instability):

The shoulder is the most commonly dislocated large joint in the body. Shoulder dislocations occurs when the head of the humerus (ball part of the ball and socket joint) is forced out of the glenoid (shoulder socket). Shoulder dislocations are so common because the shoulder is inherently unstable. The shoulder joint’s inherent instability is due to its wide range of motion and relatively small and shallow socket.

• Causes of Shoulder Dislocations:

  • Trauma: The most common cause of shoulder dislocation is a direct blow to the shoulder or a fall onto an outstretched arm. High-impact sports, such as football, hockey, and rugby, frequently lead to traumatic shoulder dislocations.

  • Congenital or Acquired Ligamentous Laxity: Individuals with naturally loose ligaments (hypermobility, Ehlers-Danlos Syndrome, ect.) or those who have stretched or torn ligaments from previous injuries are at a higher risk of dislocation.

  • Previous Dislocation: A history of shoulder dislocation very significantly increases the risk of future dislocations due to the potential for damage to stabilizing structures. Once a shoulder dislocates, depending on many factors (such as the age of the individual, gender, and sport participation), recurrent dislocation risk may be as high as 50-90%.

• Relevant Anatomy of the Shoulder:

  • Glenohumeral Joint: The main joint involved in shoulder dislocation, it is a ball-and-socket joint formed by the humeral head (ball) and the glenoid cavity of the scapula (socket). The joint's design allows for a wide range of motion but sacrifices stability.

  • Labrum: A fibrocartilaginous rim that deepens the glenoid cavity and helps stabilize the shoulder joint. Dislocation often results in a tear of the labrum, known as a Bankart lesion, which can contribute to recurrent dislocations.

  • Rotator Cuff: A group of four muscles (supraspinatus, infraspinatus, teres minor, and subscapularis) and their tendons that stabilize the shoulder joint by keeping the humeral head centered in the glenoid cavity during movement.

  • Capsule and Ligaments: The joint capsule is a fibrous envelope that surrounds the glenohumeral joint. It is reinforced by ligaments (such as the glenohumeral ligaments) that provide stability by preventing excessive movement of the humeral head.

    Bony Structures: The humeral head and glenoid cavity are the primary bony structures involved. A dislocation may cause fractures of the humerus (Hill-Sachs lesion) or the glenoid rim.

Management of Shoulder Dislocations

• Immediate Management:

  • Reduction: The primary goal in the acute setting is to reduce (relocate) the dislocated shoulder back into the glenoid cavity. This is usually done in the Emergency Room, often with sedation to relax the shoulder muscles and allow the shoulder to be safely put back into place.

  • Immobilization: After successful reduction, the shoulder is usually immobilized in a sling or brace for a period ranging from a few days to several weeks, depending on the severity of the dislocation and associated injuries. The immobilization allows time for soft tissues to heal.

• Rehabilitation:

  • Early Phase (Immobilization): Focuses on reducing inflammation and maintaining range of motion in the elbow, wrist, and hand. Pendulum exercises may be initiated to prevent shoulder stiffness without stressing the healing tissues.

  • Mid-Phase (Strengthening): Gradual introduction of range-of-motion exercises, including passive and active-assisted exercises. Strengthening exercises focus on the rotator cuff, deltoid, and scapular stabilizers to restore shoulder stability.

  • Late Phase (Functional Training): Emphasis on restoring full range of motion, strength, and proprioception. Sport-specific or activity-specific exercises are incorporated to prepare the patient for return to normal activities or sports.

  • Return to Activity: A carefully graded return to sports or high-risk activities is essential, often requiring 3-6 months of rehabilitation depending on the severity of the injury and the demands of the activity.

• Surgical Management

  • Indications for Surgery: Surgery is often recommended for patients with recurrent dislocations, significant labral tears, associated fractures, or those who fail to respond to conservative management. Young, active individuals and athletes are also more likely to benefit from surgical intervention due to the high risk of redislocation. In some cases, surgery may be recommended after a first dislocation to help prevent a future dislocation.

  • Types of Surgical Procedures:

    • Arthroscopic Bankart Repair: This procedure involves reattaching the torn labrum to the glenoid rim using anchors and sutures. It is the most common surgery for anterior shoulder instability in the United States.

    • Latarjet Procedure: Involves transferring the coracoid process with its attached muscles to the front of the glenoid to provide additional bony support and prevent anterior dislocation. This is often used in cases with significant bone loss or failed Bankart repair.

    • Capsular Shift or Plication: This procedure tightens the joint capsule to reduce excessive laxity. It may be performed in combination with a Bankart repair.

• Post-Surgical Rehabilitation

  • Similar to the non-surgical rehabilitation process but often more prolonged and cautious, especially in the early phases. The focus is on protecting the surgical repair while gradually restoring range of motion and strength. Return to sports or strenuous activities typically occurs after 6-9 months, depending on the procedure performed and the patient’s progress.

Risk Factors for Redislocation

• After Nonsurgical Management

  • Age: Younger patients, particularly those under 20, have a higher risk of redislocation due to more active lifestyles and greater demands on the shoulder.

  • Activity Level: Athletes or individuals involved in high-impact or overhead sports (e.g., football, basketball, swimming) are at increased risk of redislocation.

  • Initial Dislocation Severity: The presence of associated injuries, such as large labral tears or significant bone loss, increases the risk of redislocation.

  • Ligamentous Laxity: Individuals with inherently loose ligaments or connective tissue disorders (e.g., Ehlers-Danlos syndrome) are more prone to recurrent dislocations.

• After Surgical Management

  • Inadequate Rehabilitation: Failing to adhere to a structured rehabilitation program can lead to inadequate muscle strength and joint stability, increasing the risk of redislocation.

  • Type of Surgery: Some surgical procedures, like arthroscopic Bankart repair, have higher success rates but still carry a risk of redislocation, especially if performed on patients with significant bone loss or severe instability.

  • Post-Surgical Activity: Returning to high-risk activities too soon or without sufficient shoulder strength and stability can lead to redislocation, even after surgery.

  • Recurrent Instability Pre-Surgery: Patients with a history of multiple dislocations before surgery are at a higher risk of redislocation after surgical repair.

Shoulder Dislocation - Conclusions:

Shoulder dislocations are a common and potentially recurrent injury that can significantly impact a person’s quality of life and ability to perform daily activities or participate in sports. Management involves immediate reduction, followed by a comprehensive rehabilitation program aimed at restoring shoulder stability and function. Surgery may be necessary for those with recurrent dislocations, significant structural damage, or those at high risk for redislocation (especially younger males participating in competitive contact sports). Understanding the risk factors for redislocation, particularly after nonsurgical and surgical management, is crucial for optimizing treatment outcomes and minimizing the likelihood of future dislocations.