Luxatio Erecta: A Rare Shoulder Dislocation, Its Causes, Symptoms, and Treatment

What is a luxatio erecta?

Luxatio erecta is a rare and severe form of shoulder dislocation characterized by the humerus being displaced inferiorly, resulting in the arm being fixed in an overhead, highly abducted, and externally rotated position.

Understanding Shoulder Dislocation

The shoulder joint, or glenohumeral joint, is a highly mobile ball-and-socket joint, making it the most commonly dislocated joint in the body. Typically, shoulder dislocations occur when the head of the humerus (upper arm bone) separates from the glenoid fossa (shallow socket of the shoulder blade). The vast majority of dislocations are anterior (forward), with posterior (backward) dislocations being less common. Luxatio erecta stands apart as a distinct and particularly challenging type of dislocation due to its unique mechanism and presentation.

What is Luxatio Erecta?

Luxatio erecta, also known as inferior glenohumeral dislocation, is a very uncommon form of shoulder dislocation, accounting for only 0.5% to 5% of all shoulder dislocations. Its defining characteristic is the displacement of the humeral head inferiorly, below the glenoid fossa, often with the arm pointing directly overhead. The term "erecta" refers to the erect, or upward-pointing, position of the arm.

• Mechanism of Injury: This type of dislocation typically results from a forceful hyperabduction injury, meaning the arm is forcibly pulled or pushed excessively away from the body, often combined with axial loading or a direct blow to the shoulder. Common scenarios include:

  • Falling onto an outstretched hand with the arm fully abducted (e.g., reaching up to grab something while falling).
  • A direct impact to the superior aspect of the shoulder from below.
  • Being pulled by the arm while it is in an overhead position. The force drives the humeral head inferiorly, tearing the inferior capsule and often impacting other surrounding structures.

• Clinical Presentation: The presentation of luxatio erecta is often dramatic and easily recognizable:

  • The arm is rigidly fixed in a position of extreme abduction (160-180 degrees) and external rotation, with the hand pointing directly overhead.
  • The patient experiences intense pain and is unable to move the arm.
  • A noticeable deformity is present, with the humeral head often palpable in the axilla (armpit) and a prominent acromion (bony projection of the shoulder blade).
  • Due to the significant force and displacement, there is a high risk of neurovascular compromise, particularly to the axillary nerve and artery.

Anatomy Involved

Understanding the anatomy of the shoulder is crucial for comprehending luxatio erecta:

• Glenohumeral Joint: The articulation between the spherical head of the humerus and the shallow glenoid fossa of the scapula. Its inherent mobility makes it prone to dislocation.
• Joint Capsule and Ligaments: A fibrous capsule surrounds the joint, reinforced by glenohumeral ligaments, which provide stability. In luxatio erecta, the inferior capsule and ligaments are typically torn or avulsed.
• Rotator Cuff Muscles: A group of four muscles (supraspinatus, infraspinatus, teres minor, subscapularis) and their tendons that surround the shoulder joint, providing dynamic stability and facilitating movement. These can be injured during dislocation.
• Neurovascular Structures: Critically, the axillary nerve, which supplies sensation to the lateral shoulder and innervates the deltoid muscle (responsible for shoulder abduction), is highly vulnerable due to its close proximity to the inferior aspect of the joint. The brachial plexus (a network of nerves) and the axillary artery and vein also lie in the axilla and are at risk of stretching or compression.

Diagnosis

The diagnosis of luxatio erecta is primarily clinical, given the characteristic presentation of the arm. However, imaging is essential to confirm the diagnosis and assess for associated injuries:

• Physical Examination: Immediate assessment of the arm's fixed position and a thorough neurovascular examination (checking sensation, motor function, and pulses) are paramount.
• X-rays: Anteroposterior (AP), scapular Y-view, and axillary lateral views are standard to confirm the inferior displacement of the humeral head and to identify any associated fractures, such as fractures of the greater tuberosity, glenoid rim, or surgical neck of the humerus.

Treatment

Luxatio erecta is a medical emergency requiring immediate attention due to the high risk of complications.

• Reduction: The primary treatment is prompt reduction of the dislocation, which involves manually repositioning the humeral head back into the glenoid fossa. This procedure is typically performed under procedural sedation and/or analgesia to relax the muscles and minimize pain. Several reduction techniques exist, often involving traction-countertraction, but they must be performed carefully to avoid further injury to neurovascular structures.
• Post-Reduction Management:
  • Immobilization: After successful reduction, the shoulder is usually immobilized in a sling or shoulder immobilizer for a period, typically 2-4 weeks, to allow soft tissues to heal.
  • Post-Reduction X-rays: Repeat X-rays are taken to confirm successful reduction and to check for any fractures that may have occurred during the reduction process.
  • Neurovascular Reassessment: A comprehensive neurovascular assessment is performed again immediately after reduction to detect any new or persistent deficits.

Potential Complications

The high-energy mechanism and significant displacement associated with luxatio erecta lead to a higher rate of complications compared to other shoulder dislocations:

• Neurovascular Injury: The most common and serious complication. The axillary nerve is frequently injured, leading to numbness over the deltoid and weakness in shoulder abduction. Brachial plexus injuries and axillary artery damage (which can lead to limb ischemia) are less common but more severe.
• Rotator Cuff Tears: The forceful dislocation can tear one or more of the rotator cuff tendons.
• Fractures: Associated fractures of the humerus (greater tuberosity, surgical neck) or glenoid are not uncommon.
• Recurrent Instability: While less common than with anterior dislocations, luxatio erecta can lead to ongoing shoulder instability.
• Avascular Necrosis: A rare but serious complication where the blood supply to the humeral head is disrupted, leading to bone death.

Rehabilitation and Prevention

Rehabilitation is crucial following reduction to restore full function and prevent long-term complications.

• Rehabilitation: A structured rehabilitation program, guided by a physical therapist, typically begins after the initial immobilization period. It progresses through stages:
  • Early Phase: Focus on pain management, gentle range of motion exercises (pendulum exercises), and protecting the healing tissues.
  • Intermediate Phase: Gradual increase in active range of motion, light strengthening exercises for the rotator cuff and scapular stabilizers.
  • Advanced Phase: Progressive strengthening, proprioceptive training (balance and joint position sense), and functional exercises to prepare for activities of daily living or sport-specific movements.
• Prevention: Due to the traumatic nature of luxatio erecta, direct prevention is challenging. However, general strategies for injury prevention in sports and daily life, such as proper technique in overhead activities and fall prevention, can reduce overall risk of shoulder trauma.

Prognosis

The prognosis for luxatio erecta is generally good if the dislocation is reduced promptly and without significant neurovascular damage. Full recovery of range of motion and strength is often achievable with dedicated rehabilitation. However, the presence of associated neurovascular injuries or fractures can significantly impact the long-term outcome, potentially leading to persistent weakness, numbness, or chronic instability.

When to Seek Medical Attention

Any suspected shoulder dislocation, especially if the arm is fixed in an overhead position, constitutes a medical emergency. Immediate medical attention is required to ensure prompt diagnosis, safe reduction, and assessment for potential neurovascular complications. Do not attempt to reduce the dislocation yourself, as this can cause further damage.