Dislocated shoulder (shoulder dislocation)

The shoulder joint consists of the relatively large humeral head and the rather small glenoid cavity, which is part of the scapula. The bony contact between the glenoid cavity and the humeral head is only 30%, which allows a very large range of motion in the shoulder joint. The stability of the shoulder joint is provided primarily by soft tissue structures such as the joint capsule, muscles (rotator cuff, long biceps tendon) and ligaments. This anatomical feature leads to a certain instability, making the shoulder joint very susceptible to dislocation. Shoulder dislocation represents the most common dislocation of the human body.

Signs of shoulder dislocation may include:

• "Dent" visible on the shoulder
• Severe pain in the affected shoulder
• Restricted movement of the affected arm
• Bruise, swelling

A shoulder dislocation is usually easily recognizable from the outside: The normally round shoulder contour is interrupted by a dent under the acromion. This dent is formed by the empty glenoid cavity. In addition, the humeral head located outside the glenoid cavity can be palpated.

A shoulder dislocation is usually accompanied by severe pain and restricted movement of the affected arm. The extent to which mobility is restricted depends on the extent of the injury and any concomitant injuries.

Causes of shoulder dislocation include:

• Accidental (traumatic), B. due to fall on the outstretched arm.
• Congenital (habitual), B. due to overmobile joints.

In more than 90% of cases, shoulder dislocation occurs after an accident, e.g. a fall on the outstretched arm or a collision. Most frequently, the head of the humerus luxates forward and downward.

In young patients, the shoulder often dislocates again (reluxation) after the initial dislocation.

Much rarer is a congenital, habitual shoulder dislocation, i.e. the shoulder dislocates spontaneously during everyday movements or even during sleep. This can be the case with joints that tend to be overly mobile. Often, the shoulder will then return to normal by itself.

If a shoulder dislocation is suspected, an X-ray examination is performed to confirm the diagnosis. In the case of a shoulder dislocation, the head of the humerus is visible in the X-ray outside its socket. In addition, other bony injuries, such as an accompanying fracture of the humerus, can be detected by this examination. Often, in the case of a dislocation, the posterior portion of the humeral head is depressed by the accident mechanism and a so-called Hill-Sachs dent is formed there, which is also visible on the X-ray.

In addition to the X-ray examination, a magnetic resonance imaging (MRI) is performed. This can provide further evidence of concomitant soft tissue damage, such as injury to the joint lip(Bankard lesion) or joint capsule. Likewise, MRI examination can assess bony involvement of the glenoid and Hill-Sachs dent. A possible rotator cuff injury would also be visible on MRI.

In addition, a computed tomography (CT) scan is sometimes necessary to more accurately assess any bony defects or individual, anatomical features.

Accurate diagnosis and evaluation of the findings is critical to minimize the risk of re-dislocation (reluxation).

In the case of a shoulder dislocation, it is essential to check at an early stage in a medical examination whether there is any evidence of damage to other structures (vessels or nerves). Therefore, every shoulder dislocation must be followed by a test of the blood flow, motor skills and sensitivity of the arm.

Conservative therapy:

The following conservative therapies are available:

• Shoulder reposition
• Drug therapy
• Physiotherapy

Acute traumatic shoulder dislocation is an emergency and, like any reluxation, must be treated immediately. The head of the humerus must be put back into the socket (reduction) within 6 hours. In most cases, a short anesthetic is required for this. There are different reduction maneuvers, such as the Stimson reduction. Here, the person to be treated lies on his or her stomach with the affected arm hanging down from the couch. The head of the humerus can now be reduced into the socket by pulling on the arm, either with a weight attached to the arm or by the physician him/herself.

If the shoulder dislocation remains untreated, there is a risk of permanent nerve and vascular damage.

After successful reduction of the shoulder, the arm is immobilized in a sling. Painkillers from the group of non-steroidal anti-inflammatory drugs (NSAIDs) can be used to reduce pain. Following reduction, further imaging diagnostics must be performed to assess concomitant soft tissue and/or bony injuries. X-ray and magnetic resonance imaging are particularly suitable for this purpose (see above).

The further procedure now depends on various factors. For example, the cause of the injury (traumatic or habitual) or the age and functional requirements of the patient are important. The extent of the soft tissue or bony concomitant injury also plays a role here.

In older persons who have a lower functional demand on arm mobility or if there are no accompanying soft tissue or bony concomitant injuries, conservative therapy can be very successful. In this case, intensive physiotherapeutic therapy aimed at stabilizing the shoulder joint muscularly(rotator cuff) should be started promptly.

If there is a congenital shoulder instability, e.g. due to overmobile joints, which leads to recurrent shoulder dislocations, consistent physiotherapeutic treatment should also be performed in this case to prevent recurrent dislocations.

Operation:

The indication for surgery is given by our doctors if there is either a risk of a new large dislocation or if soft tissue or bony concomitant injuries have occurred during the dislocation. Surgery is also recommended if the therapy is unsuccessful despite intensive physiotherapeutic measures. In this case, surgical stabilization, usually by means of arthroscopy, can be used. The damaged bony structures are reconstructed and an optimal tension ratio of the soft tissues (labrum) is restored. If there is an increased risk of reluxation, open stabilization by means of bony and soft tissue reconstruction, for example Latarjet surgery, may also be necessary.

Arthroscopic surgery at a glance:

• Operation time: 60-90 min
• Anesthesia: General anesthesia
• Clinic stay: inpatient
• Fit for work: after 6 weeks
• Return to sports (RTS): after 6 months

After surgery, the shoulder should be immobilized in a sling for the first 3-6 weeks. Physiotherapeutic treatment should be started on the first day after surgery.