Dislocation of shoulder
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A dislocated shoulder is a condition in which the head of the
humerus The humerus (; ) is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius and ulna, and consists of three sections. The humeral upper extremity consists of a roun ...
is detached from the shoulder joint. Symptoms include shoulder pain and instability. Complications may include a
Bankart lesion A Bankart lesion is a type of shoulder injury that occurs following a dislocated shoulder. It is an injury of the anterior ( inferior) glenoid labrum of the shoulder. When this happens, a pocket at the front of the glenoid forms that allows th ...
, Hill-Sachs lesion, rotator cuff tear, or injury to the axillary nerve. A shoulder dislocation often occurs as a result of a fall onto an outstretched arm or onto the shoulder. Diagnosis is typically based on symptoms and confirmed by
X-rays An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation. Most X-rays have a wavelength ranging from 10 Picometre, picometers to 10 Nanometre, nanometers, corresponding to frequency, ...
. They are classified as anterior, posterior, inferior, and superior with most being anterior. Treatment is by
shoulder reduction Shoulder reduction is the process of returning the shoulder to its normal position following a shoulder dislocation. Normally, closed reduction, in which the relationship of bone and joint is manipulated externally without surgical intervention, is ...
which may be accomplished by a number of techniques. These include traction-countertraction, external rotation, scapular manipulation, and the Stimson technique. After reduction X-rays are recommended for verification. The arm may then be placed in a
sling sling may refer to: Places *Sling, Anglesey, Wales *Sling, Gloucestershire, England, a small village in the Forest of Dean People with the name * Otto Šling (1912–1952), repressed Czech communist functionary Arts, entertainment, and media * ...
for a few weeks. Surgery may be recommended in those with recurrent dislocations. Not all patients require surgery following a shoulder dislocation.  There is moderate quality evidence that patients who receive
physical therapy Physical therapy (PT), also known as physiotherapy, is one of the allied health professions. It is provided by physical therapists who promote, maintain, or restore health through physical examination, diagnosis, management, prognosis, patient ...
after an acute shoulder dislocation will not experience recurrent dislocations. It has been shown that patients who do not receive surgery after a shoulder dislocation do not experience recurrent dislocations within two years of the initial injury. About 1.7% of people have a shoulder dislocation within their lifetime. In the United States this is about 24 per 100,000 people per year. They make up about half of major joint dislocations seen in
emergency department An emergency department (ED), also known as an accident and emergency department (A&E), emergency room (ER), emergency ward (EW) or casualty department, is a medical treatment facility specializing in emergency medicine, the acute care of pati ...
s. Males are affected more often than females. Most shoulder dislocations occur as a result of sports injuries.


Signs and symptoms

* Significant
pain Pain is a distressing feeling often caused by intense or damaging stimuli. The International Association for the Study of Pain defines pain as "an unpleasant sensory and emotional experience associated with, or resembling that associated with, ...
, sometimes felt along the arm past the shoulder. * Sensation that the shoulder is slipping out of the joint during abduction and external rotation. * Shoulder and arm held in external rotation (anterior dislocation), or adduction and internal rotation (posterior dislocation). Resistance of all movement. * Numbness of the arm. * Visibly displaced shoulder. Some dislocations result in the shoulder appearing unusually square. * No palpable
bone A bone is a Stiffness, rigid Organ (biology), organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red blood cell, red and white blood cells, store minerals, provid ...
on the side of the shoulder.


Diagnosis

A diagnosis of shoulder dislocation is often suspected based on the person's history and physical examination. Radiographs are made to confirm the diagnosis. Most dislocations are apparent on radiographs showing incongruence of the glenohumeral joint. Posterior dislocations may be hard to detect on standard AP radiographs, but are more readily detected on other views. After reduction, radiographs are usually repeated to confirm successful reduction and to detect bone damage. After repeated shoulder dislocations, an MRI scan may be used to assess soft tissue damage. In regards to recurrent dislocations, the apprehension test (anterior instability) and sulcus sign (inferior instability) are useful methods for determining predisposition to future dislocation. There are three main types of dislocations: anterior, posterior, and inferior.


Anterior (forward)

In over 95% of shoulder dislocations, the humerus is displaced
anteriorly Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...
. In most of those, the head of the humerus comes to rest under the
coracoid process The coracoid process (from Greek κόραξ, raven) is a small hook-like structure on the lateral edge of the superior anterior portion of the scapula (hence: coracoid, or "like a raven's beak"). Pointing laterally forward, it, together with the ...
, referred to as sub-coracoid dislocation. Sub-
glenoid The glenoid fossa of the scapula or the glenoid cavity is a bone part of the shoulder. The word ''glenoid'' is pronounced or (both are common) and is from el, gléne, "socket", reflecting the shoulder joint's ball-and-socket form. It is a sha ...
, sub
clavicular The clavicle, or collarbone, is a slender, S-shaped long bone approximately 6 inches (15 cm) long that serves as a strut between the shoulder blade and the sternum (breastbone). There are two clavicles, one on the left and one on the right ...
, and, very rarely, intrathoracic or retroperitoneal dislocations may also occur. Anterior dislocations are usually caused by a direct blow to, or fall on, an outstretched arm. The person typically holds his/her arm externally rotated and slightly abducted. A Hill–Sachs lesion is an impaction of the head of the humerus left by the glenoid rim during dislocation. Hill-Sachs deformities occur in 35–40% of anterior dislocations. They can be seen on a front-facing X-ray when the arm is in internal rotation.
Bankart lesion A Bankart lesion is a type of shoulder injury that occurs following a dislocated shoulder. It is an injury of the anterior ( inferior) glenoid labrum of the shoulder. When this happens, a pocket at the front of the glenoid forms that allows th ...
s are disruptions of the glenoid labrum with or without an avulsion of bone fragment. Damage to the axillary artery and axillary nerve (C5, C6) may result. The axillary nerve is injured in 37% making it the most commonly injured structure with this type of injury. Other common, associated, nerve injuries include injury to the suprascapular nerve (29%) and the
radial nerve The radial nerve is a nerve in the human body that supplies the posterior portion of the upper limb. It innervates the medial and lateral heads of the triceps brachii muscle of the arm, as well as all 12 muscles in the posterior osteofascial comp ...
(22%). Axillary nerve damage results in a weakened or paralyzed deltoid muscle and as the deltoid atrophies unilaterally, the normal rounded contour of the shoulder is lost. A person with injury to the axillary nerve will have difficulty in abducting the arm from approximately 15° away from the body. The supraspinatus muscle initiates abduction from a fully
adducted Motion, the process of movement, is described using specific anatomical terms. Motion includes movement of organs, joints, limbs, and specific sections of the body. The terminology used describes this motion according to its direction relative ...
position. File:Luxation epaule.PNG, An anterior dislocation of the shoulder File:AnterDisAPMark.png, Anterior dislocation of the right shoulder. AP X ray File:AnterDisMark.png, Anterior dislocation of the right shoulder. Y view X ray.


Posterior (backward)

Posterior dislocations are uncommon, and are typically due to the muscle contraction from
electric shock Electrical injury is a physiological reaction caused by electric current passing through the body. The injury depends on the density of the current, tissue resistance and duration of contact. Very small currents may be imperceptible or produce ...
or seizure. They may be caused by strength imbalance of the rotator cuff muscles. People with dislocated shoulders typically present holding their arm internally rotated and adducted, and exhibiting flattening of the anterior shoulder with a prominent coracoid process. Posterior dislocations may go unrecognized, especially in an
elderly Old age refers to ages nearing or surpassing the life expectancy of human beings, and is thus the end of the human life cycle. Terms and euphemisms for people at this age include old people, the elderly (worldwide usage), OAPs (British usage ...
person and in people who are in the state of unconscious trauma. An average interval of 1 year was noted between injury and diagnosis in a series of 40 people.


Inferior (downward)

Inferior dislocation is the least likely, occurring in less than 1%. This condition is also called luxatio erecta because the arm appears to be permanently held upward or behind the head. It is caused by a hyper abduction of the arm that forces the humeral head against the acromion. Such injuries have a high complication rate as many vascular, neurological, tendon, and
ligament A ligament is the fibrous connective tissue that connects bones to other bones. It is also known as ''articular ligament'', ''articular larua'', ''fibrous ligament'', or ''true ligament''. Other ligaments in the body include the: * Peritoneal li ...
injuries are likely to occur from this mechanism of injury.


Treatment

Prompt medical treatment should be sought for suspected dislocation. Usually, the shoulder is kept in its current position by use of a splint or sling. A pillow between the arm and
torso The torso or trunk is an anatomical term for the central part, or the core, of the body of many animals (including humans), from which the head, neck, limbs, tail and other appendages extend. The tetrapod torso — including that of a human ...
may provide support and increase comfort. Strong analgesics are needed to allay the pain of a dislocation and the distress associated with it.


Reduction

Shoulder reduction Shoulder reduction is the process of returning the shoulder to its normal position following a shoulder dislocation. Normally, closed reduction, in which the relationship of bone and joint is manipulated externally without surgical intervention, is ...
may be accomplished with a number of techniques including traction-countertraction, external rotation, scapular manipulation, Stimson technique, Cunningham technique, or Milch technique. Pain can be managed during the procedures either by procedural sedation and analgesia or injected
lidocaine Lidocaine, also known as lignocaine and sold under the brand name Xylocaine among others, is a local anesthetic of the amino amide type. It is also used to treat ventricular tachycardia. When used for local anaesthesia or in nerve blocks, lidoca ...
into the shoulder joint. Injecting lidocaine into the joint may be less expensive and faster. If a shoulder cannot be relocated in the emergency room, relocation in the operating room may be required. This situation occurs in about 7% of cases. Stimson procedure is the least painful, widely used shoulder reduction technique. In this procedure a weight is attached to the wrist while the injured arm is hanging off an examination table for between 20 and 30 minutes. The arm is then slowly rotated until the shoulder is relocated. Sedatives are used in Stimson procedure and first time Stimson reduction for acute shoulder dislocation requires wearing arm slings for between 2 and 4 weeks.


Post-reduction

There is no strong evidence of a difference in outcomes when the arm is immobilized in internal versus external rotation following an anterior shoulder dislocation. A 2008 study of 300 people for almost six years found that conventional shoulder immobilisation in a sling offered no benefit.


Surgery

In young adults engaged in highly demanding activities
shoulder surgery Shoulder surgery is a means of treating injured shoulders. Many surgeries have been developed to repair the muscles, connective tissue, or damaged joints that can arise from traumatic or overuse injuries to the shoulder. Dislocated shoulder A d ...
may be considered. Arthroscopic surgery techniques may be used to repair the
glenoidal labrum The glenoid labrum (glenoid ligament) is a fibrocartilaginous structure (not a fibrocartilage as previously thought) rim attached around the margin of the glenoid cavity in the shoulder blade. The shoulder joint is considered a ball and socket jo ...
, capsular ligaments,
biceps The biceps or biceps brachii ( la, musculus biceps brachii, "two-headed muscle of the arm") is a large muscle that lies on the front of the upper arm between the shoulder and the elbow. Both heads of the muscle arise on the scapula and join ...
long head anchor or
SLAP lesion Slap or slapping may refer to: * Slapping (strike), a method of striking with the palm of the hand * Slapping (music), a musical technique used with stringed instruments * Slap tonguing, a musical technique used on wind instruments * ''Slap'' ( ...
or to tighten the shoulder capsule. Arthroscopic stabilization surgery has evolved from the
Bankart repair A Bankart repair is an operation for habitual anterior shoulder dislocation. The joint capsule In anatomy, a joint capsule or articular capsule is an envelope surrounding a synovial joint.Bankart repair A Bankart repair is an operation for habitual anterior shoulder dislocation. The joint capsule In anatomy, a joint capsule or articular capsule is an envelope surrounding a synovial joint.Latarjet operation. Although posterior dislocation is much less common, instability following it is no less challenging and, again, some form of bone augmentation may be required to control instability. Damaged ligaments, including labral tears, occurring as a result of posterior dislocations may be treated arthroscopically. There remains those situations characterized by multidirectional instability, which have failed to respond satisfactorily to rehabilitation, falling under the AMBRI classification previously noted. This is usually due to an overstretched and redundant capsule which no longer offers stability or support. Traditionally, this has responded well to a 'reefing' procedure known as an open inferior capsular shift. More recently, the procedure has been carried out as an arthroscopic procedure, rather than open surgery, again with comparable results. Most recently, the procedure has been carried out using radio frequency technology to shrink the redundant shoulder capsule (thermal capsular shrinkage); while long-term results of this development are currently unproven, recent studies show thermal capsular shrinkage have higher failure rates with the highest number of cases of instability recurrence and re-operation.


Prognosis

After an anterior shoulder dislocation, the risk of a future dislocation is about 20%. This risk is greater in males than females.


See also

*
Shoulder problems Shoulder problems including pain, are one of the more common reasons for physician visits for musculoskeletal symptoms. The shoulder is the most movable joint in the body. However, it is an unstable joint because of the range of motion allowed. ...


References


External links

{{DEFAULTSORT:Dislocated Shoulder Injuries of shoulder and upper arm Shoulder Dislocations, sprains and strains Wikipedia medicine articles ready to translate