Shoulder Dislocations
Figure 1: Shoulder anatomy, physiotherapy Frenchs Forest and Macquarie Park
Anatomy of the shoulder:
The shoulder joint is a ball-and-socket joint formed by the head of the upper arm bone (humerus) and the shallow socket (glenoid) of the shoulder blade (scapula).
It is one of the most mobile joints in the body, allowing for a wide range of motion, but this mobility also makes it prone to dislocations.
Types of shoulder dislocations:
Shoulder dislocations can be classified into several types based on the direction in which the humerus (upper arm bone) dislocates relative to the glenoid (shoulder socket). The most common types include:
Figure 2: Shoulder dislocations, physiotherapy Frenchs Forest and Macquarie Park
1. Anterior Shoulder Dislocation:
This is the most common type of shoulder dislocation, accounting for about 95% of cases.
In an anterior dislocation, the humerus is forced out of the shoulder socket and moves forward, usually beneath the coracoid process of the scapula.
Anterior dislocations often occur due to a force that pushes the arm backward or rotates it outward, such as falling onto an outstretched arm or a direct blow to the front of the shoulder.
2. Posterior Shoulder Dislocation:
In a posterior dislocation, the humerus is displaced backward out of the glenoid socket.
Posterior dislocations are less common and often result from forceful contractions of the muscles surrounding the shoulder, such as during seizures, electric shock, or traumatic injury.
3. Inferior Shoulder Dislocation (Luxatio Erecta):
This is a rare type of shoulder dislocation where the humerus is displaced downward, below the level of the glenoid socket.
Inferior dislocations are typically caused by extreme trauma or force applied to the abducted arm, such as a fall from a height or a high-energy impact.
4. Multidirectional Shoulder Instability:
Multidirectional instability refers to a condition where the shoulder joint is prone to dislocating in multiple directions, often due to underlying ligamentous laxity or muscle imbalance.
Patients with multidirectional instability may experience recurrent dislocations or subluxations (partial dislocations) in various directions, including anterior, posterior, and inferior.
5. Traumatic vs. Atraumatic Dislocations:
Shoulder dislocations can also be categorised as traumatic or atraumatic based on the underlying cause.
Traumatic dislocations result from a sudden force or injury to the shoulder joint, as described above.
Atraumatic dislocations occur without a clear traumatic event and are often associated with underlying conditions such as ligamentous laxity, joint hypermobility, or repetitive overuse.
Understanding the specific type of shoulder dislocation is important for determining the appropriate treatment approach, as management strategies may vary depending on the direction of displacement, severity of injury, and individual patient factors.
Causes of shoulder disolocations:
Shoulder dislocations can occur due to various causes, including:
1. Traumatic Injury: The most common cause of shoulder dislocations is a traumatic event that forces the humerus out of the glenoid socket. This can happen due to:
Falls onto an outstretched hand or directly onto the shoulder.
Motor vehicle accidents.
Sports-related injuries, especially in contact sports like football, rugby, or wrestling.
Direct blows or impacts to the shoulder area.
2. Repetitive Overuse: Overuse of the shoulder joint, particularly in activities that involve repetitive overhead motion or lifting heavy weights, can gradually weaken the supporting structures of the shoulder, making it more susceptible to dislocations. This is often seen in athletes who engage in throwing sports (e.g., baseball pitchers) or occupations that involve frequent overhead work (e.g., painters, carpenters).
3. Joint Hypermobility: Some individuals naturally have increased joint laxity or hypermobility, which can predispose them to shoulder instability and dislocations. In these cases, the ligaments and soft tissues around the shoulder joint may be inherently looser, making it easier for the humerus to slip out of place, especially with certain movements or positions.
4. Muscle Weakness or Imbalance: Weakness or imbalance in the muscles surrounding the shoulder joint, particularly the rotator cuff muscles, can contribute to instability and an increased risk of dislocations. When the muscles responsible for stabilizing the shoulder are not adequately strong or coordinated, they may fail to support the joint during movement, leading to instability and potential dislocations.
5. Congenital Factors: In some cases, structural abnormalities present at birth (congenital anomalies) may predispose individuals to shoulder instability and dislocations. These abnormalities may affect the shape or alignment of the bones forming the shoulder joint, making it more prone to instability.
6. Previous Shoulder Dislocations: Once an individual has experienced a shoulder dislocation, they are at a higher risk of experiencing recurrent dislocations in the future. Each dislocation episode can stretch or damage the supporting ligaments and soft tissues, further compromising the stability of the shoulder joint and increasing the likelihood of subsequent dislocations.
7. Seizures or Electric Shocks: In rare cases, shoulder dislocations can occur as a result of sudden muscle contractions or spasms, such as those seen during epileptic seizures or electric shocks. The forceful muscle contractions can forcefully dislocate the shoulder joint, particularly if the arm is in an awkward position at the time of the event.
Signs and Symptoms of shoulder dislocations:
Intense pain in the shoulder area.
Swelling and bruising around the shoulder joint.
Visible deformity or asymmetry of the shoulder.
Limited range of motion, inability to move the arm.
Numbness or tingling in the arm or hand due to nerve compression.
Diagnosis of shoulder dislocations:
Diagnosing a shoulder dislocation typically involves a combination of medical history, physical examination, and imaging studies. Here are the steps involved in diagnosing a shoulder dislocation:
1. Medical History: The healthcare provider will begin by taking a thorough medical history, asking about the circumstances surrounding the injury and any previous shoulder issues or dislocations. It's important to provide information about the onset of symptoms, the nature of the injury, and any factors that may have contributed to the dislocation.
2. Physical Examination:
Visual Inspection: The healthcare provider will visually inspect the shoulder for signs of deformity, swelling, bruising, and asymmetry.
Palpation: Gentle palpation of the shoulder area helps assess tenderness and detect any abnormalities in the bone or soft tissues.
Range of Motion: The range of motion of the shoulder joint will be assessed, although this may be limited due to pain and instability.
Neurovascular Examination: A thorough examination of nerve and blood vessel function is important to check for signs of nerve compression, such as numbness or tingling, and to ensure adequate blood flow to the arm.
3. Imaging Studies:
X-rays: X-ray imaging is often used to confirm the diagnosis and determine the specific type of dislocation. X-rays can reveal the position of the humerus in relation to the glenoid socket and identify any associated fractures or bony abnormalities.
CT Scan or MRI: In some cases, especially if there are concerns about associated soft tissue injuries or if the dislocation is not clearly visible on X-rays, a computed tomography (CT) scan or magnetic resonance imaging (MRI) may be ordered.
4. Reduction Confirmation:
If the shoulder dislocation has already been reduced (put back into place) before seeking medical attention, imaging may still be necessary to confirm the reduction and assess for any residual instability or injuries.
It's crucial to seek medical attention promptly if a shoulder dislocation is suspected. Attempting to reduce the dislocation without proper medical expertise can lead to complications, and a healthcare professional is trained to safely and effectively perform the reduction procedure.
Once the diagnosis is confirmed, the healthcare provider will determine the appropriate course of treatment, which may include immobilization, rehabilitation, and, in some cases, surgical intervention. Early and accurate diagnosis is key to managing shoulder dislocations effectively and preventing long-term complications.
Treatment of shoulder dislocations:
The treatment for a shoulder dislocation depends on various factors, including the severity of the dislocation, the presence of associated injuries, the patient's age, activity level, and overall health. Here's an overview of the treatment options:
1. Closed Reduction:
In many cases, the initial treatment for a shoulder dislocation involves a procedure called closed reduction. This procedure is performed by a healthcare provider and involves gently manipulating the dislocated humerus back into its normal position within the glenoid socket.
Closed reduction may be done in an emergency department, urgent care center, or physician's office. Sedation or anesthesia may be used to help relax the muscles and reduce pain during the procedure.
2. Immobilisation:
After the shoulder has been successfully reduced, it's typically immobilised to allow the soft tissues around the joint to heal. This may involve wearing a sling or shoulder immobiliser for a period of time, usually several weeks.
Immobilisation helps prevent further injury and allows the damaged ligaments, tendons, and other structures to heal properly.
3. Pain Management:
Pain management is an important aspect of treatment, especially in the acute phase following a shoulder dislocation. Over-the-counter or prescription pain medications may be prescribed to help manage pain and discomfort.
Ice packs applied to the shoulder can also help reduce pain and swelling in the initial stages.
Figure 3: Shoulder rehabilitation, Physiotherapy Frenchs Forest and Macquarie Park
4. Rehabilitation Exercises:
Once the acute phase of treatment is complete and the shoulder is no longer immobilized, a structured rehabilitation program is initiated. Physical therapy exercises are designed to improve strength, flexibility, and range of motion in the shoulder joint.
Rehabilitation exercises may include gentle stretching, range of motion exercises, strengthening exercises for the muscles surrounding the shoulder (especially the rotator cuff muscles), and functional activities to improve shoulder stability and control.
5. Surgical Intervention:
In some cases, particularly if there are recurrent dislocations, associated fractures, or significant soft tissue injuries, surgical intervention may be necessary.
Surgical options may include repairing damaged ligaments or labrum, tightening the joint capsule, or stabilizing the shoulder joint using techniques such as arthroscopic stabilization or open surgery.
6. Prevention:
Once the initial treatment is complete, efforts are made to prevent future shoulder dislocations. This may involve avoiding activities or movements that could increase the risk of shoulder instability, such as overhead throwing motions or heavy lifting.
Strengthening exercises and proprioceptive training can help improve shoulder stability and reduce the risk of recurrent dislocations.
The specific treatment plan for a shoulder dislocation is tailored to each individual based on their unique circumstances and goals. Close follow-up with a healthcare provider is important to monitor progress, address any complications, and ensure optimal recovery.
Complications:
Shoulder dislocations can lead to several potential complications, especially if they are not promptly treated or if there are associated injuries. Some of the common complications include:
1. Recurrent Dislocations: Individuals who have experienced a shoulder dislocation are at a higher risk of recurrent dislocations, particularly if the underlying cause of the initial dislocation is not addressed or if the rehabilitation process is inadequate. Each subsequent dislocation can further damage the soft tissues around the shoulder joint, leading to increased instability and a higher likelihood of future dislocations.
2. Shoulder Instability: Recurrent dislocations or untreated ligamentous injuries can result in chronic shoulder instability, where the shoulder joint feels loose or unstable. This can cause discomfort, decreased functional ability, and a sensation of the shoulder "giving way" during certain movements.
3. Bankart Lesion: A Bankart lesion is a specific type of injury to the labrum (a ring of cartilage surrounding the glenoid socket) that commonly occurs with anterior shoulder dislocations. If left untreated, a Bankart lesion can contribute to ongoing shoulder instability and increase the risk of recurrent dislocations.
4. Hill-Sachs Lesion: A Hill-Sachs lesion is a defect or indentation in the humeral head (the ball-shaped end of the upper arm bone) that can occur as a result of the humerus impacting against the glenoid rim during a dislocation event. Large or significant Hill-Sachs lesions can compromise the stability of the shoulder joint and increase the risk of future dislocations.
5. Rotator Cuff Tears: The forceful nature of a shoulder dislocation can sometimes result in injuries to the rotator cuff muscles or tendons, which help stabilize the shoulder joint and facilitate arm movements. Rotator cuff tears can cause pain, weakness, and limited range of motion in the shoulder, and they may require surgical repair in some cases.
6. Nerve or Vascular Damage: Severe shoulder dislocations can cause compression or injury to the nerves and blood vessels surrounding the shoulder joint. This can lead to symptoms such as numbness, tingling, weakness, or circulation problems in the arm or hand. Prompt medical evaluation is necessary if there are signs of nerve or vascular involvement.
7. Arthritis: Chronic shoulder instability or repeated dislocations can accelerate wear and tear on the cartilage lining the shoulder joint, leading to degenerative changes and the development of arthritis over time. Arthritis can cause pain, stiffness, and loss of function in the shoulder joint.
8. Frozen Shoulder (Adhesive Capsulitis): Prolonged immobilization or restricted movement following a shoulder dislocation can increase the risk of developing a condition known as frozen shoulder, characterized by stiffness, pain, and limited range of motion in the shoulder joint.