Dislocated Shoulder: Acute & Chronic Complications, Factors, and Management

What are the complications of a dislocated shoulder?

A dislocated shoulder, a significant orthopedic injury where the head of the humerus fully separates from the glenoid fossa of the scapula, can lead to a range of immediate and long-term complications affecting the joint's stability, function, and surrounding neurovascular structures.

Understanding Shoulder Dislocation and Its Impact

The shoulder joint, or glenohumeral joint, is the most mobile joint in the human body, a characteristic that also makes it the most frequently dislocated. Its stability relies heavily on a complex interplay of static stabilizers (the glenoid labrum, joint capsule, and glenohumeral ligaments) and dynamic stabilizers (the rotator cuff muscles and surrounding periscapular musculature). When a dislocation occurs, these stabilizing structures are often stretched, torn, or otherwise damaged, setting the stage for various complications.

Acute Complications (Immediate Post-Injury)

Upon dislocation, the forceful displacement can cause immediate damage beyond the joint's primary separation.

• Neurovascular Injury: This is a critical acute concern.
  • Nerve Damage: The axillary nerve is most commonly affected due to its close proximity to the inferior aspect of the glenohumeral joint. Damage can result in numbness or tingling over the deltoid region and weakness in shoulder abduction. Less commonly, other nerves of the brachial plexus can be injured, leading to more widespread sensory and motor deficits in the arm and hand.
  • Vascular Damage: While less common, the subclavian artery and vein can be stretched or compressed, particularly in severe or recurrent dislocations, potentially leading to compromised blood flow to the arm.
• Rotator Cuff Tears: Especially prevalent in older individuals (over 40 years old), the force of dislocation can avulse or tear one or more of the rotator cuff tendons (supraspinatus, infraspinatus, subscapularis, teres minor). This often manifests as persistent weakness and pain even after the shoulder has been reduced.
• Fractures: The dislocation event itself can cause concomitant fractures.
  • Hill-Sachs Lesion: A compression fracture on the posterior-lateral aspect of the humeral head, caused by impact against the anterior rim of the glenoid during dislocation.
  • Bankart Lesion: An avulsion fracture of the anterior-inferior glenoid rim, often occurring with anterior dislocations. This involves the detachment of the glenoid labrum and sometimes a piece of bone.
  • Greater Tuberosity Fracture: A fracture of the bony prominence on the humerus where some rotator cuff tendons attach, often seen in older patients.
• Ligamentous and Capsular Damage: The glenohumeral ligaments and joint capsule are stretched or torn during dislocation, compromising the static stability of the joint. This damage is a primary contributor to future instability.
• Muscle Spasm and Severe Pain: The immediate response to dislocation is intense pain and involuntary muscle guarding, making reduction difficult without proper analgesia and muscle relaxation.

Chronic Complications (Long-Term Issues)

If not managed appropriately, or despite optimal management, a dislocated shoulder can lead to persistent problems.

• Recurrent Instability and Dislocation: This is the most common long-term complication, particularly in younger, active individuals. Once the static stabilizers (labrum, capsule, ligaments) are damaged, the shoulder becomes more susceptible to repeat dislocations with less force. Each recurrence can further damage the joint, leading to progressive bone loss from the glenoid or humeral head.
• Chronic Pain: Persistent pain can result from ongoing instability, nerve damage, unaddressed rotator cuff tears, or the development of arthritic changes within the joint.
• Stiffness and Reduced Range of Motion (ROM): Prolonged immobilization, scar tissue formation (adhesions), or capsular contracture can lead to significant loss of shoulder mobility. Fear of re-dislocation can also lead to apprehension and self-limitation of movement.
• Osteoarthritis (Post-traumatic Arthritis): Over time, especially with recurrent dislocations, the articular cartilage surfaces of the humerus and glenoid can wear down prematurely due to abnormal joint mechanics and repeated trauma. This can lead to chronic pain, stiffness, and crepitus (grinding sensation).
• Muscle Atrophy and Weakness: Disuse due to pain or apprehension, nerve damage, or unaddressed rotator cuff pathology can lead to significant muscle wasting and weakness around the shoulder girdle, impacting functional capacity.
• Adhesive Capsulitis (Frozen Shoulder): While less common as a direct complication, prolonged immobilization or inadequate rehabilitation following a dislocation can sometimes precipitate the development of adhesive capsulitis, characterized by severe stiffness and pain.

Factors Influencing Complications

Several factors can influence the likelihood and severity of complications:

• Age: Younger individuals (under 20) are at higher risk for recurrent instability, while older individuals (over 40) are more prone to rotator cuff tears and fractures.
• Mechanism of Injury: High-energy trauma vs. low-energy events.
• Direction of Dislocation: Anterior dislocations are most common and often associated with Bankart and Hill-Sachs lesions.
• Number of Prior Dislocations: Each subsequent dislocation increases the risk of further structural damage and chronic instability.
• Associated Injuries: Presence of concomitant fractures or nerve damage.
• Quality of Initial Reduction: Timely and proper reduction minimizes soft tissue damage.
• Adherence to Rehabilitation: A structured and progressive physical therapy program is crucial for restoring stability, strength, and range of motion, significantly reducing the risk of long-term issues.

Importance of Proper Management

Given the potential for significant complications, a dislocated shoulder requires immediate medical attention. Proper management typically involves:

• Prompt Reduction: Safely returning the humeral head to the glenoid fossa.
• Thorough Assessment: Imaging (X-rays, MRI) to identify associated fractures, labral tears, or rotator cuff injuries.
• Immobilization: A brief period of immobilization to allow initial healing.
• Structured Rehabilitation: A comprehensive physical therapy program focusing on pain management, restoring range of motion, strengthening the rotator cuff and periscapular muscles, and proprioceptive training to enhance dynamic stability.
• Surgical Intervention: May be necessary for recurrent instability, significant labral tears (e.g., Bankart repair), or large rotator cuff tears that do not respond to conservative management.

Conclusion

A dislocated shoulder is more than just a temporary displacement; it is a significant injury that can lead to a cascade of acute and chronic complications impacting the shoulder's long-term health and function. Understanding these potential issues underscores the critical importance of prompt medical evaluation, accurate diagnosis of associated injuries, and adherence to a comprehensive rehabilitation program to mitigate risks and optimize recovery.