Shoulder dislocation, ligament injuries, labrum tear, Bankart lesion, traumatic tear, shoulder instability, fracture, shoulder pain, shoulder blade pain
The shoulder joint consists of the articulation between the humerus and the scapula, where the round head of the humerus fits against the relatively flat joint surface of the scapula. The shape of the joint surfaces allows for a wide range of motion, but also makes the joint unstable and prone to dislocations.
A shoulder dislocation occurs when the humerus is pushed excessively relative to the scapula, either forward, backward, or downward. Shoulder dislocations make up the majority of large joint dislocations and are the most common joint dislocation in the body. Shoulder dislocations typically occur forward (about 95% of all dislocations), but backward or downward dislocations are also possible. The shoulder joint can dislocate either completely or partially, and it may return to its normal position on its own or remain dislocated, in which case it should be reduced (put back into place) as soon as possible.
In shoulder dislocations, the connective tissues that hold the bones together are stretched or torn, which can result in shoulder joint instability. A forward shoulder dislocation may also cause injury to the axillary nerve, making it difficult to use the upper limb.
The diagnosis of a shoulder dislocation is based on patient history, clinical examination, and imaging studies. Most shoulder dislocations are treated conservatively under the guidance of a physiotherapist.
Ethiology & epidemiology
The shoulder dislocates more frequently than any other joint in the body. The primary risk factors for dislocation are young age and being male. Shoulder dislocations are often caused by a twisting injury or fall affecting the shoulder joint, with the majority of injuries occurring in contact sports.
However, dislocation can also occur without significant external trauma, particularly if the shoulder joint is structurally loose or if there have been multiple previous dislocations.
The incidence of shoulder dislocations in the Nordic countries is approximately 24 cases per 100,000 person-years, with about 70% of cases occurring in men.
The risk of recurrent shoulder dislocation is increased by:
Previous dislocation, inadequate rehabilitation, or poor tissue healing after a dislocation
Young age and a physically active lifestyle
Tissue damage during dislocation, such as: rotator cuff injuries, labrum tears or glenoid fractures
Shoulder joint anatomy
The shoulder joint is formed between the head of the humerus and the glenoid fossa of the scapula. The complex anatomy of the shoulder allows for a remarkable range of motion, but its inherent instability requires support and coordination from surrounding structures to maintain stability during all movements.
Bony anatomy:
The head of the humerus is spherical and articulates with the shallow, pear-shaped socket of the scapula. The glenoid fossa of the scapula is relatively shallow, which enhances shoulder mobility but also makes it inherently unstable.
The glenoid fossa is surrounded by a fibrous cartilage ring called the labrum, which deepens the socket and provides some passive support to the shoulder joint. In the case of a labrum injury, the translational support of the shoulder joint is reduced by approximately 20% compared to an intact labrum.
Cross-section of the shoulder joint anatomy: Pay particular attention to the rotator cuff muscles that form the cuff. Proper coordination and activation of the rotator cuff are crucial for shoulder joint stability. The rotator cuff is comprised of the infraspinatus, supraspinatus, subscapularis, and teres minor muscles, along with the shoulder joint capsule.
Stability:
Despite its significant mobility, the shoulder joint is fundamentally unstable due to the balance between mobility and stability. The shallow socket provides less bony support compared to other ball-and-socket joints, such as the hip, making the shoulder more prone to dislocations. Stability is primarily achieved through the surrounding muscles, tendons, ligaments, and the joint capsule, which together form a stabilizing cuff around the shoulder joint.
The rotator cuff consists of the capsule structure of the shoulder joint and four muscles surrounding the shoulder joint, which collectively help stabilize the head of the humerus within the glenoid fossa of the scapula. Additionally, other muscles that cross the shoulder joint also contribute to maintaining the stability and function of the shoulder.
Mechanism of Shoulder Dislocation Injury
Typical injury mechanisms involve significant forces and the shoulder joint being twisted beyond its ranges. Dislocations often occur in contact sports, traffic accidents, motor sports or due to sudden movements during a fall. An unstable shoulder or one with a history of dislocations can also dislocate with minimal force or twisting.
The specific injury mechanism and related complications depend on the direction of the shoulder dislocation. Below are the types of dislocations, their typical mechanisms and potential complications.
Forward Shoulder Dislocation
Forward shoulder dislocation is the most common type (about 95% of all shoulder dislocations). It occurs when the arm is twisted into excessive abduction and external rotation. In this position, the support from ligaments and dynamic stability are often inadequate, increasing the risk of dislocation. The greatest susceptibility occurs when the arm is at 90° abduction and 90° external rotation.
Possible Complications and Tissue Damage:
Ligament injuries and resulting shoulder instability
Hill-Sachs lesion (Impression fracture on the posterior-lateral aspect of the humeral head)
Bankart lesion (Tear of the anterior-inferior labrum)
Bony Bankart lesion (Fracture of the anterior-inferior glenoid rim)
Rotator cuff tendon injuries
Stretching and injuries to the brachial plexus or axillary nerve
Damage to the axillary artery
Backward Shoulder Dislocation
Backward shoulder dislocation is rarer, accounting for only about 3% of all shoulder dislocations. It typically occurs when the humeral head is displaced backward while the shoulder is in abduction and internal rotation. Common causes include seizures, electric shocks or traffic accidents.
Possible Complications and Tissue Damage:
Rotator cuff tendon injuries
Reverse Bankart lesion
Reverse Hill-Sachs lesion
Glenoid fractures
Downward Shoulder Dislocation
Downward shoulder dislocations are the rarest, constituting only about 0.5% of all shoulder dislocations. These can result from a fall onto the head with an attempt to cushion the impact with the arms or from a sudden downward force applied to the abducted and externally rotated arm.
Possible Complications and Tissue Damage:
Tears of the lower portion of the shoulder joint capsule
Other soft tissue injuries
Stretching and injuries to the brachial plexus or axillary nerve
Glenoid fractures
Symptoms
The most common symptom of a shoulder dislocation is severe and sharp pain in the shoulder that prevents movement and use of the joint. In addition to pain, symptoms can vary greatly depending on the direction of the dislocation and any potential damage caused. Weakness in the affected arm is often observed, which can result from either intense pain or a possible nerve injury.
Depending on the extent of any tissue damage, there may be swelling, warmth and redness around the shoulder joint and surrounding structures. These changes are typically due to inflammation caused by the tissue injury. Bruising and hematomas are also common and tend to spread downward along the upper arm.
The muscles surrounding the shoulder may become tense and feel tight following a dislocation. This is a protective mechanism of the body to guard the injured area. Increased muscle tension can be uncomfortable and may make shoulder use difficult after the dislocation.
If the dislocation causes stretching or damage to the brachial plexus or individual nerves, symptoms may include numbness, tingling, weakness, or nerve pain in the affected arm.
Treatment
The primary treatment for a shoulder dislocation is conservative. If the shoulder remains dislocated, it should be reduced as soon as possible. This is typically performed in the emergency department after appropriate pain relief has been administered.
Following reduction, treatment combines both pharmacological and non-pharmacological pain management techniques, immobilization and physical therapy. The goal of treatment is to alleviate pain and improve functional and work capacity. This is achieved through a precise, progressive and individualized exercise program, often incorporating mobility-enhancing and maintaining exercises as well as manual therapy.
Medications typically include a combination of pain relievers and anti-inflammatory drugs and inflammation may also be managed with cold therapy applied multiple times a day.
If the shoulder dislocates repeatedly or if there is significant tissue damage, surgical intervention may be required. Post-surgery, it is crucial to rehabilitate the shoulder to restore full strength, mobility, and stability.
Physical therapy
The content of physical therapy following a shoulder dislocation depends on the severity of possible tissue damage and individual needs. Therefore, rehabilitation always begins with a thorough assessment of the underlying factors, which informs the design of the therapy program. The primary goals of physical therapy are to reduce pain and swelling and to restore normal shoulder mobility, strength, and stability.
Rehabilitation is often a lengthy process, but most of the work is done through self-directed exercises, so a large number of physical therapy sessions are typically not required. Restoring shoulder mobility and maintaining muscle strength are key components of the rehabilitation process.
Immobilization may be necessary for a first-time dislocated shoulder, but in cases of recurrent dislocations, rehabilitation can often begin immediately. During immobilization, the focus is on maintaining the mobility of the arm and wrist and reducing swelling and pain caused by inflammation.
In the early stages of rehabilitation, the focus is on restoring shoulder mobility and preventing muscle loss. This is achieved through light isometric exercises and gentle movements. These exercises promote blood circulation, reduce swelling, help manage pain and decrease muscle loss. As shoulder mobility and stability improve, exercises can be intensified to enhance dynamic stability, movement control and muscle strength.
Rehabilitation progresses according to the individual’s recovery and the next phase is only started when the goals of the previous stage are met. The ultimate aim of rehabilitation is full functional recovery and a return to normal daily activities or sports. Towards the end of the rehabilitation process, the focus shifts to strengthening the shoulder and improving body control, especially in the movements and positions where the original injury occurred.
Each dislocation is unique, so the precise content and progression of rehabilitation depend entirely on the individual's specific needs and goals.
What to Do After a Shoulder Dislocation
It is crucial to seek professional help as soon as possible after a shoulder dislocation. If immediate help is not available, you can use the following methods to temporarily manage the dislocated shoulder:
Stay Calm and Avoid Panic: Try to remain as calm as possible. Panic can increase muscle tension, making it harder to manage the dislocation.
Immobilize the Shoulder: Keep the arm as still as possible to prevent further damage. You can create a temporary sling using a shirt, towel, or cloth to support the arm and prevent movement.
Position the Arm: Keep the arm close to your body and avoid excessive movement. Support the injured arm with your other hand to prevent unnecessary motion.
Protect the Injured Area: Follow the Peace & Love method to protect the injured area. Learn more about the Peace & Love method here.
Do Not Attempt to Relocate the Shoulder Yourself: Trying to reposition the shoulder without proper technique can damage blood vessels, nerves, or soft tissues.
Avoid Further Injury: Do not perform any activities that involve the use of the arm or shoulder. Rest the injured shoulder completely until professional help is available.
Seek Medical Attention Immediately: Get medical treatment as soon as possible. The dislocated shoulder should be repositioned by a healthcare professional to avoid long-term damage.
Consult a Physiotherapist: Once the shoulder has been repositioned, it is important to seek physiotherapy for individualized rehabilitation guidance. A combination of physiotherapy and self-directed exercises will help restore shoulder stability, strength, and mobility.