ability to place your hand functionally above your head, behind your
back, and at all points in between is largely dependent on the
shoulder’s extreme range of motion. This degree of flexibility defines
it as an unconstrained joint. The stability can be divided into static
and dynamic constraints. Statically, there is a small flat glenoid
surface articulating with the large humeral head. The depth of the
glenoid cavity is augmented by the labrum, which also serves as the
anchor point for the capsular ligaments to the glenoid and the origin
of the biceps. The glenoid articulation and the labrum in themselves
have little constraint to the glenoid humeral joint. The ligaments
serve as additional static restraints at the extreme range of motion.
The dynamic component of stability for the glenohumeral joint comes
from the surrounding musculature. The rotator cuff muscles
(supraspinatus, infraspinatus, and teres minor) plus the subscapularis
and the long head of the biceps are very important dynamic stabilizers (3).
Another degree of dynamic stability comes through the scapulothoracic
articulation which provides one third of the total active motion of the
shoulder girdle. The position of the scapula is the foundation off
which the glenohumeral joint functions. The periscapular muscles are
extremely important in positioning the glenoid cavity correctly as well
as providing a stable platform from which the glenohumeral joint
functions. The neurovascular bundle lies directly anterior and inferior
to the glenohumeral joint, which accounts for the frequency of
neurovascular injuries, especially with anterior dislocations that are
associated with shoulder trauma.
The majority of patients presenting with acute shoulder pain are
suffering from either a dislocation, fracture, or muscle rupture.
Still, it is important to consider that a variety of other entities may
cause acute shoulder pain including:
Cervical disc disease (C5 nerve root)
Superior sulcus tumors (Pancoast tumor or metastatic disease)
Cholecystitis (right shoulder)
Cardiac symptoms (typically left shoulder)
The majority of shoulder disorders can be
managed and produce a good outcome by nonsurgical treatment which
centers around physical therapy to regain the strength of muscles
around the joint and range-of-motion exercises to maintain flexibility.
Approximately 50% of all major joint dislocations involve the
glenohumeral joint. Dislocations are commonly classified by direction
(anterior, inferior, posterior, or multidirectional), onset (acute,
recurrent, chronic), and by etiology (traumatic, minimally traumatic,
atraumatic, microanterior instability). Anterior dislocations are the
most common. Dislocations that occur in patients younger than 20 years
old typically involve an avulsion of the ligaments and labrum from the
glenoid. Dislocations that occur in patients older than 30 years of age
tend to involve interligamentous tears. Dislocations in patients older
often associated with rotator cuff tears and/or greater tuberosity
fractures. The older the patient, the lower the rate of recurrence of
dislocations, but older patients also have a higher rate of
posttraumatic shoulder stiffness (13).
Mechanism of injury.
The injury usually results from a traumatic event in which the position
of the arm is in an externally rotated and forward-flexed or an
In patients younger than 20 years of age,
the anterior capsule and labrum are avulsed from the glenoid,
occasionally with a small fragment of bone (Bankart lesion). The
humeral head dislocates anterior to the glenoid fossa and under the
coracoid process. A compression fracture may occur on the
posterolateral humeral head (Hill-Sachs lesion) from impaction of the
head on the anterior edge of the glenoid (2).
In patients older than 40 years of age,
intrasubstance failure of the anterior capsule and an acute rotator
cuff tear can occur. An acute rotator cuff tear can be difficult to
repair if not detected within the first 6 weeks postinjury.
Recent basic science studies have shown
that sectioning of the anterior capsule alone does not cause gross
anterior instability. Damage to the posterior or superior capsule must
also occur for a complete anterior dislocation to occur.
Individuals with an acute dislocation hold their arm in an adducted
position. There is a loss of symmetry of their shoulders and the
humeral head can be palpated anterior and inferior to the coracoid
process. Any attempt at range of motion of the shoulder is extremely
painful. A thorough neurovascular check of the upper extremity is
necessary before any attempt is made to reduce the dislocation.
Attention to checking the sensory function of the axillary nerve over
the lateral aspect of the shoulder is important.
Roentgenograms. In all patients with a suspected initial dislocation of the shoulder, a standard trauma series should be obtained (10).
This series includes an anteroposterior and a transscapular lateral
(“Y”) view. If the presence and direction of the dislocation are not
clearly evident, an axillary view is obtained. This view is difficult
to obtain and painful for the patient; it may require physician
assistance to position the patient’s shoulder. Any associated
tuberosity fractures or epiphyseal injuries should be clearly
Treatment of the first dislocation
Reduction without general anesthesia.
Prompt reduction of the dislocation provides a great deal of pain
relief. To achieve a gentle and pain-free reduction, muscle relaxation
and pain relief are required. Multiple methods of reduction have been
described, but the author prefers one of the following methods:
Prone reduction under lidocaine block (14).
The patient is allowed to remain sitting on the examination table, and
the posterior aspect of the shoulder is sterilely prepped. Ten to 20 mL
of 1% lidocaine are injected into the glenohumeral joint posteriorly.
The patient is then placed prone on the examination table with the
involved arm and shoulder hanging in a dependent position over the edge
of the table. A 10-lb weight is suspended from the patient’s wrist.
After 10 to 15 minutes, good analgesia and relaxation are present and
the shoulder can be reduced by elevation and forward rotation of the
medial border of the scapula.
Reduction by traction.
If the first method fails, the patient is repositioned supine and
additional intravenous (IV) sedation is administered. A sheet is placed
around the patient centered in the axillary region. An assistant holds
the two ends of the sheet above the patient and provides
countertraction while the physician grasps the forearm of the involved
shoulder and gently pulls in a line of 30 degrees of abduction and 20
to 30 degrees of forward flexion. Sustained traction for 5 minutes may
be necessary. Vigorous and forceful attempts
at reduction are to be avoided since this may result in a fracture, especially in older osteopenic patients.
Reduction under anesthesia.
If the aforementioned methods fail or if a significant fracture is
present, a reduction under general anesthetic with complete muscle
relaxation is indicated. The shoulder typically reduces easily with
little risk of further damage to the glenohumeral joint or its
Postreduction treatment. The length of immobilization has no effect on the incidence of redislocations (12).
The shoulder should be immobilized for a brief period as needed for
pain control after a dislocation or subluxation episode. A
range-of-motion and rotator cuff strengthening program is initiated
early, but the extremes of range of motion for forward flexion or
external rotation are avoided. Patients are allowed to return to sports
and other activities when the shoulder has good strength and minimal
apprehension in an abducted, externally rotated position (1, 6). A general rule is the younger the patient, the higher the possibility of recurrent instability (9).
Recurrent dislocations or subluxations. If necessary, the shoulder is reduced as in B.4
(above). Occasionally, if witnessed “on the field” and the evaluation
suggests a recurrent dislocation without fracture, then an attempt for
reduction can be made prior to radiographic imaging. If anesthesia is
not available, reduction is the best pain relief. A postreduction,
physical therapy program is prescribed as in B.5
(above). Recurrent instability episodes may be painful and disabling.
Many different types of surgical repairs have been described (12,15,16,19). The author prefers either an open or arthroscopic Bankart repair or capsular shift reconstruction (15,17).
The open type of repair has been associated with success rates of 97%
with few significant complications. Arthroscopically assisted repairs
are technically possible but have not yet achieved success rates
comparable to open capsular repairs, especially in athletes in high
Damage to the nerves
originating with the brachial plexus occurs in 5% to 14% of shoulder
dislocations. The axillary nerve and musculocutaneous nerve are most
commonly injured. Most injuries are a neuropraxia, and a full recovery
is typical. The same is true with postoperative neurologic injuries.
While the injured nerve is recovering, it is important not to allow any
secondary contractures of the joint to develop.
Rotator cuff tears
are common in patients older than 40 years with an anterior
dislocation. If good range of motion and strength have not returned
within 3 to 4 weeks after the injury, visualization of the rotator cuff
with magnetic resonance imaging (MRI) or ultrasound is indicated.
Mechanism of injury.
Posterior instability results from a fall on an adducted and forward
flexed arm, which drives the head of the humerus posterior to the
glenoid fossa. A compression fracture of the anterolateral aspect of
the humeral head may develop (reverse Hill-Sachs lesion). In younger
individuals, an avulsion of the posterior labrum with a small fragment
of the posterior glenoid rim (reverse Bankart lesion) may occur.
Seizures or electrocution are other mechanisms that often produce
posterior instability (7).
An obvious clinical deformity is typically not present and the patient
may be complaining of only minimal symptoms. Many posterior
dislocations are not diagnosed and reduced in the emergency department.
External rotation of the shoulder is limited and painful, and is the
hallmark of a posterior shoulder dislocation.
Anteroposterior views often are normal and misleading except that the
arm is positioned in a markedly internally rotated position, which
produces a “light bulb sign” with the proximal humerus. A transscapular
“Y” view and an axillary view show the posterior position of the
Muscle relaxation via IV sedation is recommended. Reductions can
usually be obtained by gentle traction on the arm with an additional
anterior and laterally directed force applied to the posterior aspect
of the humeral head. Postreduction treatment is similar to that for
anterior dislocation (B.5.)
except internal rotation and adduction extremes are avoided. If the
shoulder dislocates immediately after being reduced, the arm should be
braced in a neutral rotation and an abducted position for 4 weeks to
maintain stability. Posterior dislocations that result from seizures or
electrocutions may have large or reverse Hill-Sachs lesions that lead
to further instability episodes.
that occur as a result of traumatic events and have evidence of
ligament damage may be treated with a reverse capsular shift. Many
patients with posterior instability do not have a history of a
significant traumatic event that initiated the instability and may be
able to voluntarily dislocate or sublux
their shoulder. These patients have poor operative results and should
undergo treatment with physical therapy and activity or lifestyle
Multidirectional instability (MDI)
Mechanism of injury.
MDI is diagnosed when there is clinical evidence that the shoulder is
unstable in two or more directions. There is often no history of
significant trauma and the patient may be able to voluntarily dislocate
The typical patient is a “double-jointed” adolescent female. A sulcus
sign is present and the patient is apprehensive with the arm in
positions that stress both the anterior and posterior capsule.
Often, radiographs are normal. The presence of a Hill-Sachs or a
reverse Hill-Sachs lesion is detected on a Stryker notch view but often
is not in fact present.
Treatment. Nonoperative treatment is strongly advised because operative management has a high failure rate (18).
A procedure using thermal energy to arthroscopically “shrink” the
redundant capsule has not proven successful and has been associated
with significant complications including capsular necrosis and
Inferior dislocations are rare. The patient’s arm is locked in an
overhead position. Reduction is obtained by IV sedation and relaxation.
The arm is then reduced with lateral distraction while the arm is
brought out of an abducted position.
Mechanism of injury.
Acute tears of the rotator cuff are rare and occur mainly in
individuals younger than 40 years old who have a history of significant
trauma. Attritional tears of the rotator cuff are more common and occur
in older individuals (see Chap. 16).
Examination (see Chap. 16).
Damage to the glenohumeral joint, including the greater tuberosity, is
best assessed on an anteroposterior view, obtained with the arm in 30
degrees of external rotation. An outlet view and an axillary view
should also be obtained. Young individuals who are suspected of having
a rotator cuff tear on history or examination should undergo an MRI
scan or an ultrasound evaluation to assess the status of their rotator
young or active patients with a true acute rotator cuff tear, early
(within 3 months) operative repair is indicated. Early repair is also
indicated in those cases associated with a displaced avulsion fracture
of the greater tuberosity (4). Displacement of a greater tuberosity fragment by more than 1 cm correlates highly with an acute rotator cuff tear.
Mechanism of injury.
Injuries of the long head of the biceps (LHB) tendon may occur with
forceful elbow flexion or hand supination. Eighty percent of the cases
are associated with ongoing rotator cuff problems and shoulder
impingement syndrome. Steroid use for body conditioning is an
increasingly common etiology.
A visible asymmetry of the injured versus noninjured upper arm is
evident when the patient is asked to “make a biceps” muscle. This
deformity is called a “Popeye” sign.
Ruptures of the LHB tendon are treated nonoperatively. The indications
for repair are mainly cosmetic in nature because little functional
disability results. In patients with evidence of impingement syndrome,
an appropriate workup of the rotator cuff is indicated, particularly in
active patients or those under 60 years of age.
with a bench press lift, a seated fly lift, or a similar functional
maneuver. The patient has pain and an ecchymosis in the anterior
shoulder. On examination, there is a loss or defect in the anterior
axillary line. Treatment is usually symptomatic except in the heavy
laborer or athlete in whom early operative repair is indicated.
Ruptures at the muscle tendon junction are difficult to repair and have
a worse outcome than tears at the bone/tendon or tendon/tendon
interface. A preoperative MRI scan is indicated in those individuals
for whom operative repair is being considered to determine at what
level the defect has occurred.
with early range of motion of the shoulder girdle. Displaced fractures
involving greater than 25% percent of the articular surface of the
glenoid or glenoid neck fractures with medial displacement are
generally treated operatively to reduce the risk of glenohumeral
instability or arthritis (11).
emergency department under analgesia or intraarticular lidocaine, sling
for comfort followed by assisted range-of-motion exercises beginning at
2 to 3 weeks after injury
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