Dislocated Shoulder

Introduction to Dislocated Shoulder

A dislocated shoulder, also known as shoulder subluxation or dislocation, occurs when the humerus bone is partially or completely displaced from the glenohumeral joint, compromising shoulder joint stability and function.​

1.​1 Definition and Overview

A dislocated shoulder is a condition characterized by the displacement of the humerus bone from the glenohumeral joint, which connects the humerus to the scapula.​ This joint is a ball-and-socket joint that allows for a wide range of motion in three planes of space.​ The shoulder joint is considered one of the most mobile joints in the human body, but this mobility comes at the cost of stability, making it prone to dislocation.​ A dislocated shoulder can be caused by various factors, including trauma, sports injuries, and falls. The condition can be acute or chronic, and its severity can vary depending on the extent of the displacement and the presence of associated injuries, such as labral tears or scapula fractures. Prompt medical attention is essential to prevent long-term damage and promote optimal recovery.​

Causes of Shoulder Dislocation

Shoulder dislocation occurs when the humerus bone is forced out of the glenohumeral joint, often due to traumatic or non-traumatic events that compromise shoulder joint stability and integrity, leading to subluxation or dislocation.​

2.​1 Traumatic Causes

Traumatic causes of shoulder dislocation typically involve a sudden, forceful impact or movement that compromises the integrity of the glenohumeral joint.​ Common examples include falls onto an outstretched hand or directly onto the shoulder, sports-related injuries, and motor vehicle accidents.​ The force generated by such events can cause the humerus bone to be displaced from the glenoid cavity, leading to subluxation or dislocation.​ In some cases, the trauma may also result in concomitant injuries, such as labral tears, scapula fractures, or other soft tissue damage.​ The severity of the traumatic event and the direction of the force applied to the shoulder joint can influence the likelihood and type of shoulder dislocation.​ A thorough evaluation is necessary to assess the extent of the injury and develop an effective treatment plan.​

2.​2 Non-Traumatic Causes

Non-traumatic causes of shoulder dislocation encompass a range of factors that can contribute to joint instability and increase the likelihood of dislocation. Muscle imbalances, particularly weakness of the rotator cuff muscles, can compromise shoulder stability.​ Additionally, conditions such as shoulder laxity, where the joint capsule and ligaments are excessively loose, can predispose individuals to dislocation.​ Certain genetic conditions, such as Ehlers-Danlos syndrome, can also affect the structural integrity of the glenohumeral joint. Furthermore, repetitive movements or activities that involve heavy lifting, throwing, or overhead motions can lead to chronic wear and tear on the joint, ultimately contributing to non-traumatic shoulder dislocation. A comprehensive evaluation is necessary to identify the underlying causes of non-traumatic shoulder dislocation and develop an effective treatment plan to address these factors and prevent future episodes.​

Types of Shoulder Dislocation

Shoulder dislocations are classified based on the direction and extent of humeral head displacement, with primary types including anterior, posterior, inferior, and intrathoracic dislocations, each with distinct clinical implications.​

3.​1 Anterior Dislocation

An anterior dislocation, also known as an anterior shoulder dislocation, occurs when the humeral head is displaced anteriorly and inferiorly in relation to the glenoid cavity of the scapula. This type of dislocation is the most common, accounting for up to 97% of all shoulder dislocations.​ The mechanism of injury typically involves abduction and external rotation of the arm, causing the humeral head to be displaced from the glenoid cavity.​ The subscapularis muscle and the labrum are often injured, and the dislocation may be associated with a Bankart lesion or a Hill-Sachs lesion.​ Anterior dislocations can be further classified into subluxations, which are incomplete dislocations, and luxations, which are complete dislocations.​ Prompt recognition and treatment of anterior dislocations are essential to prevent long-term complications, such as recurrent instability and degenerative joint disease.​

3.​2 Posterior Dislocation

A posterior dislocation, also known as a posterior shoulder dislocation, occurs when the humeral head is displaced posteriorly in relation to the glenoid cavity of the scapula.​ This type of dislocation is relatively rare, accounting for only 2-4% of all shoulder dislocations.​ The mechanism of injury typically involves a fall onto an outstretched hand٫ a direct blow to the anterior aspect of the shoulder٫ or a seizure.​ The subscapularis muscle and the posterior labrum are often injured٫ and the dislocation may be associated with a reverse Hill-Sachs lesion or a McLaughlin lesion. Posterior dislocations can be challenging to diagnose٫ as the presentation may be subtle and plain radiographs may not always demonstrate the dislocation.​ A high index of suspicion and specialized imaging studies٫ such as CT scans or MRI٫ may be necessary to confirm the diagnosis and guide treatment.​

Symptoms and Complications of Shoulder Dislocation

Symptoms and complications of shoulder dislocation can vary in severity, encompassing pain, limited mobility, and potential long-term consequences, including labral tears, scapula fractures, and chronic shoulder instability.​

4.​1 Common Symptoms

Common symptoms of a dislocated shoulder can vary depending on the severity and type of dislocation.​ Typically, patients experience sudden, severe pain and limited mobility in the affected arm.​ The pain may radiate down the arm or up to the neck and is often exacerbated by movement.​ Additionally, some patients may exhibit visible deformity, bruising, or swelling around the shoulder joint.​ Numbness, tingling, or weakness in the arm or hand are also common complaints.​ In cases of anterior dislocation, the humerus bone may be palpable in front of the shoulder joint.​ Patients may also report difficulty performing daily activities, such as dressing, grooming, or reaching overhead.​ A thorough medical evaluation is necessary to accurately diagnose and treat a dislocated shoulder, as symptoms can be similar to those of other shoulder injuries, such as shoulder separation or subluxated shoulder.

4.​2 Potential Complications

Potential complications of a dislocated shoulder can be severe and may significantly impact quality of life. Recurrent shoulder instability is a common complication, leading to repeated episodes of dislocation or subluxation.​ Nerve damage, particularly to the axillary nerve, can result in persistent numbness, tingling, or weakness in the affected arm.​ Additionally, vascular injuries, such as disruption of the axillary artery, can lead to ischemia or even gangrene.​ A labral tear or scapula fracture may also occur concomitantly with a dislocated shoulder, requiring additional treatment.​ Furthermore, prolonged immobilization can result in joint stiffness, limited mobility, and muscle atrophy.​ In rare cases, a dislocated shoulder can lead to chronic pain, arthritis, or long-term disability.​ Prompt medical attention and proper treatment are essential to minimize the risk of these potential complications and ensure optimal outcomes for patients with a dislocated shoulder.​

Treatment and Rehabilitation of Shoulder Dislocation

Treatment for a dislocated shoulder involves prompt reduction, immobilization, and rehabilitation to restore joint stability, strength, and mobility, with the goal of minimizing complications and achieving optimal functional outcomes.

5.​1 Initial Treatment

Initial treatment for a dislocated shoulder involves prompt reduction of the dislocation, which can be achieved through closed reduction or surgical intervention. Closed reduction is typically performed under sedation or anesthesia to minimize discomfort and promote relaxation.​ The goal of reduction is to restore the humerus bone to its normal position within the glenohumeral joint, thereby alleviating pain and reducing the risk of further complications.

Following reduction, the affected shoulder is immobilized in a sling or other orthotic device to stabilize the joint and facilitate healing.​ Pain management is also a crucial aspect of initial treatment, with medication and other interventions used as needed to minimize discomfort and promote patient comfort.​ In some cases, imaging studies such as X-rays or MRI may be ordered to confirm the diagnosis and rule out associated injuries, such as labral tears or scapula fractures.

5.​2 Rehabilitation and Physical Therapy

Rehabilitation and physical therapy play a crucial role in restoring function, strength, and stability to the shoulder joint following dislocation.​ A comprehensive rehabilitation program typically commences once the initial pain and inflammation have subsided, and may include a range of exercises and interventions aimed at improving range of motion, strengthening surrounding musculature, and enhancing proprioception.

Under the guidance of a qualified physical therapist, patients engage in targeted exercises, such as resisted movements, isometric contractions, and functional activities, to promote optimal recovery and minimize the risk of recurrent instability or shoulder separation.​ Additionally, manual therapy techniques, including joint mobilization and soft tissue massage, may be employed to address any residual stiffness, muscle imbalances, or scar tissue adhesions that may be hindering the healing process. Regular follow-up appointments with the treating physician are also essential to monitor progress and address any concerns or complications that may arise during the rehabilitation period;