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Evaluation and Treatment of Shoulder Injuries
Injuries to the shoulder are exceedingly common,
but their diagnosis is not always straightforward. This review discusses
the characteristics and mechanisms of injury and the clinical signs
that indicate when orthopedic referral is necessary.
By Kathryn L. Johns, MD, and Francis L. Counselman,
MD
| Dr. Johns is chief resident
in the department of emergency medicine at Eastern Virginia
Medical School and Dr. Counselman is distinguished professor
of emergency medicine and chairman and program director in the
department of emergency medicine at Eastern Virginia Medical
School and Emergency Physicians of Tidewater, Norfolk, Virginia.
He is a member of the Emergency Medicine editorial board. |
Shoulder pain is a common presenting complaint in both primary
and emergency care. The pain may be acute and traumatic or insidious,
chronic, and disabling. It also may originate not in the joint itself--where
it is regarded as true shoulder pain--but elsewhere in the body.
Because such referred pain can possibly be caused by a life-threatening
disorder, the clinician must be able to recognize the patterns of
referred pain.
Patients who have true acute or traumatic pain are more likely
to present to the emergency department (ED) than to the primary
care office, whereas those whose pain occurs after minor falls and
athletic mishaps, including fractures, dislocations, and soft tissue
injuries, may present to any medical facility. Approximately 8%
to 13% of athletic injuries involve the shoulder, and about 50%
of all joint dislocations seen in the ED are shoulder dislocations.
Chronic shoulder pain, which is more likely to be seen in the primary
care facility, can be very disabling and distressing to a patient.
Initially, primary care physicians can provide conservative treatment,
but a referral to a specialist may be necessary if such treatment
fails or the disease causing the pain progresses.
To properly diagnose and treat shoulder pain, and to know when
consultation or referral is necessary, the clinician must understand
and be familiar with the functional anatomy of the shoulder, the
common mechanisms of injury, the appropriate radiologic studies
and their proper interpretation, and the available treatments for
each condition.
Although the shoulder is very complex, the joint and the disorders
that affect it are not difficult to understand. In addition, the
differential diagnosis for true shoulder pain is not extensive and
can be narrowed easily by focusing on particular findings from a
patient's history and physical examination.
The first priority is to determine whether a patient's shoulder
pain is truly that and not evidence of another disorder. A thorough
history and physical examination is essential for detecting the
possible sources of pain referred to the shoulder, such as a cervical
spine disorder, thoracic outlet syndrome, Pancoast's tumor, acute
coronary syndrome, diaphragmatic irritation, and diseases of the
stomach, esophagus, gallbladder, or pancreas. Once such disorders
have been ruled out, the rest of the examination can focus on the
shoulder itself.
Acute pain originating within the shoulder usually appears suddenly
after some traumatic event or episode of heavy lifting or strenuous
exercise. The timing and mechanism of injury are very important,
as are the precise location, intensity, and pattern of radiation,
if any. A history of injury to the shoulder is also important and
can influence the choice of treatment.
Insidious or chronic shoulder pain is very different from acute
pain. Although affected patients often report a history of strenuous
exercise or activity that involves prolonged over-the-head arm motion,
they are usually unable to identify precisely when the pain began
or what precipitated it. It is possible, however, for chronic pain
to be the result of a previous acute injury. The location of certain
types of pain may be difficult for a patient to define. Patients
who have pain caused by rotator cuff tendonitis often place their
hand over the lateral shoulder, whereas those with a clavicle fracture
can point to its exact location with a single finger. When an impingement
syndrome is the cause, pain will typically appear as the shoulder
is used, but a dull, achy pain will also linger for some time afterward
and worsen at night as the disorder progresses. Pain originating
within the shoulder does not usually radiate past the elbow.
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Anatomy of the Shoulder
Three bones make up the shoulder joint: the scapula, humerus, and
clavicle. The head of the humerus is seated in the glenohumeral
recess, which is formed by the acromion and coracoid processes of
the scapula. The clavicle extends from the sternum to the acromion
and represents the only connection between the upper extremity and
the axial skeleton.
Functionally, the shoulder girdle is made up of four joints--the
glenohumeral joint, acromioclavicular (AC) joint, sternoclavicular
(SC) joint, and scapulothoracic articulation. The glenohumeral joint
provides most of the movement of the upper extremity. The scapula
contributes to the movement of the upper extremity by rotating outwardly
60º during abduction and flexion of the arm. The clavicle and
clavicular joints are also important in the mobility of the arm.
The clavicle is capable of 35º of elevation and also rotates
on its long axis 45º to 50º. The AC joint, however, has
only about 5º to 8º of motion and plays a smaller role
in the mobility of the arm.
The joints of the shoulder girdle are held together by a complex
of structures and tissues consisting of a joint capsule, ligaments,
and muscle tendons. The ligaments involved in the shoulder girdle
include the five scapulohumeral ligaments--the coracohumeral ligament
and the superior, middle, anteroinferior, and posteroinferior glenohumeral
ligaments--all of which are important static stabilizers of the
shoulder. Injuries to the middle and anteroinferior ligaments may
occur during anterior dislocation and contribute to recurrent anterior
instability. Surgical repair of these avulsions is necessary to
prevent recurrent traumatic instability.
The humerus is held in the joint by the rotator cuff muscles: the
supraspinatus, infraspinatus, teres minor, and subscapularis muscles,
known collectively by the acronym SITS. The trapezius, serratus
anterior, rhomboids, and latissimus dorsi also play a role in stabilizing
the scapula and neck during shoulder movement. The tendons of the
rotator muscle blend together with the joint capsule of the glenohumeral
joint. Each rotator cuff muscle acts to hold the humeral head in
the joint, in addition to performing individual roles in movements
of the arm, including elevation and internal and external rotation.
The soft tissue and bony support structure in the shoulder provide
a remarkable degree of stability to a joint that has a tremendous
range of motion and strength. In a normal shoulder, with all the
supporting tissue intact, the center of the humeral head is maintained
within one millimeter of the center of the glenoid cavity throughout
the entire range of motion of the shoulder. When the arm is at rest,
no support from the muscles of the shoulder girdle is necessary
to keep the joint in place.
In spite of the impressive stability these tissues and structures
impart to the normal shoulder, that support can be overcome under
certain circumstances, resulting in dislocation and other injuries.
The location of the humeral head in the glenoid fossa is most precarious
when the arm is placed any of three arrangements: adducted, flexed
and internally rotated; abducted and elevated; or adducted at the
side at the side of the body with the scapula rotated downward.
Interestingly, a family history of shoulder instability may be
more linked to shoulder stability than was originally thought. Investigators
in several studies have found a family history of shoulder instability
in 15% to 27% of patients who had recurrent anterior instability,
and they also noted bilateral instability was evident in 50% of
patients whose family history was positive, as compared with only
26% of those whose family history was negative.
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Examining the Shoulder
The physical examination of the shoulder should begin with a visual
inspection. Both shoulders should be exposed to permit comparison,
which is essential. Simple observation of both shoulders can reveal
atrophy, deformity, ecchymosis, and asymmetry. Palpating both shoulders
and comparing the findings is an important method of identifying
deformities, abnormal prominence, tenderness, warmth, swelling,
and crepitus.
An assessment of the active range of motion in both shoulders should
be performed while a patient is in the seated position. An evaluation
of passive range of motion, with the patient supine, will be necessary
if any abnormalities are noted during the evaluation of the active
range of motion. The actual motion of the joint in each direction
should be estimated and recorded, in degrees, so that the results
can be compared with those of later evaluations. An evaluation of
the strength of each rotator cuff muscle, a procedure that will
be discussed later, is also important.
Also essential to a thorough physical examination of the shoulder
is a neurovascular evaluation of the upper extremity. This examination
includes a test of a patient's shoulder muscle strength and deep
tendon reflexes as well as of his or her response to light touch,
two point discrimination, and pin prick tests. In addition, the
ulnar, radial, and brachial pulses should be noted.
After the patient's medical history is obtained and physical examination
completed, radiographic studies, if necessary, are the next step.
The traditional radiographic views used to assess a painful shoulder
include the anteroposterior, transthoracic lateral, axillary lateral,
and transscapular Y views. For traumatic injuries, the recommended
views are the true anteroposterior, the transscapular, and the axillary
lateral views, but other specialized shoulder views are often used
for evaluating specific injuries and situations.
Anteroposterior (AP) view. When a beam is passed
at an angle of 90º through a normal shoulder, the glenoid rim
will not be obscured by the humerus, as occurs when the beam is
directed toward the patient at a 90º angle. Both views are
acceptable, but a clinician inspecting the film must know which
view was intended so that he or she can interpret the film properly.
The true AP permits visualization of the glenoid rim and is useful
in the evaluation of glenohumeral arthritis. The AP view obtained
in internal and external rotation will also reveal the lesser and
greater tuberosities and thus any evidence of their possible fracture.
Axillary lateral view. Providing the best true
lateral view of the shoulder, the axillary lateral view can reveal
the relationship of the humeral head to the glenoid fossa and any
evidence of a possible fracture of the lesser tuberosity, humeral
head, coracoid process, and glenoid rim. Because the axillary lateral
view necessitates the abduction of a patient's arm, this view is
difficult to obtain when an acute injury is present, and the technique
therefore may be compromised. In cases in which a traumatic injury
makes abduction of the arm impossible, a reverse projection or modified
axillary view may be used.
Transscapular Y view. Also called the scapulolateral
or Mercedes-Benz view, the transscapular Y view is the defining
view for determining the position of the humeral head after a dislocation.
The arms of the Y are formed by the confluence of the coracoid process
(interior arm) and the acromion (posterior arm); the stem of the
Y is formed by the body of the scapula. In a normal shoulder, the
humeral head should fall directly over the union of the three segments
of the Y. An anterior dislocation will cause the head to obscure
the view of the coracoid process; in a posterior dislocation, the
head will obscure the view of the scapular spine and acromion.
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Acute Pain Due to Dislocation
Glenohumeral dislocation is the most common shoulder dislocation,
representing 95% of all shoulder injuries, followed by acromioclavicular
and sternoclavicular joint dislocations.
Glenohumeral dislocation. Occurring most commonly
in men aged 20 to 30 years and in those aged 61 to 80 years, glenohumeral
dislocation is often caused by a fall on an abducted, externally
rotated arm. The associated pain is severe, which along with muscle
spasm makes reduction difficult. Patients typically hold the affected
arm in near-adduction and slight external rotation. When possible,
the shoulder should be stabilized in the field by placing a pillow
or rolled-up blanket under the arm and immobilizing it with a swathe.
Posterior and inferior dislocations of the glenohumeral joint are
rare. Posterior dislocations, which account for 2% to 4% of all
joint dislocations, are usually caused by seizure, electrocution,
or significant trauma. The mechanism of injury involves the axial
loading of an adducted, internally rotated arm. This type of dislocation
is more likely to be chronic or recurrent. On physical examination,
an affected patient will hold the arm in internal rotation and adduction.
The coracoid process may appear quite prominent.
Radiologic studies can be difficult to interpret, as the AP view
may appear relatively normal. Abnormalities that must be carefully
sought out on the AP film include the loss of the profile of the
greater tuberosity, which is caused by the internal rotation of
the humerus and is known as the light bulb sign; the absence of
the normal half-moon formed by the overlap of the humeral head on
the glenoid; and the rim sign, in which the space between the glenoid
and the humeral head is increased--that is, greater than 6 mm.
The scapular Y view can be extremely helpful in detecting this
type of dislocation, because the humeral head will be clearly visible
posterior to the glenoid. Either a transscapular view or an axillary
lateral view is mandatory for detecting a suspected posterior dislocation.
The AP view may also reveal the trough sign: a curvilinear density
on the frontal projection of the humeral head, parallel to the articular
cortex of the humerus. Such a sign indicates the presence of a reverse
Hill-Sachs lesion, an impaction fracture of the posterior lateral
portion of the humeral head, which almost invariably accompanies
a posterior dislocation.
The most serious consequence of a posterior dislocation is missed
diagnosis. If these dislocations are not promptly reduced, the joint
may become "locked," necessitating open reduction and internal fixation.
Inferior dislocations represent less than 1% of all shoulder dislocations.
They are caused by hyperabduction, which is usually associated with
significant trauma. Affected patients present in a fairly classic
position, with the arm held above 90° of abduction and the
elbow flexed. Typically the arm is held resting on the head. The
humeral head may be palpable in the axilla. An AP film of the shoulder
will reveal the humeral head inferior to its normal position and
the humeral shaft parallel to the scapular spine. This finding helps
to distinguish an inferior dislocation from a subglenoid anterior
dislocation, in which the humeral shaft is parallel to the chest
wall.
Acromioclavicular joint dislocation. Accounting
for 12% of all dislocations about the shoulder girdle, dislocations
of the acromioclavicular joint are more common in men than in women
and are usually associated with contact sports, motor vehicle accidents,
and falls. When the point of the shoulder is pulled down under force,
the AC ligament ruptures first, then the CC ligament, followed by
the deltoid and trapezius attachments, which are torn from the distal
clavicle. If the mechanism was a fall on an outstretched hand (FOOSH),
only the AC ligaments will be injured.
Acromioclavicular joint injuries are graded according to the extent
of ligamentous injury. Grade I represents an AC ligament sprain;
grade II, a complete AC ligament rupture, with a widened joint space.
In a grade III ligamentous injury, the AC and CC ligaments and their
muscle attachments are totally disrupted, and the joint space is
significantly widened. Because standard radiographic views will
over-penetrate the AC joint, specific views such as the AP cephalic
tilt and axillary lateral views will be necessary to examine that
joint. The normal CC joint space distance is 1.1 to 1.3 cm; a difference
of greater than 5 mm between the two shoulders is diagnostic of
complete CC disruption. Stress view films, which are obtained as
a patient holds weights to accentuate the widening of the joint,
are no longer recommended.
The treatment of a grade I injury begins with a sling. After a
period of one to weeks, the affected patient can begin range of
motion exercises. A sling is also required for a grade II ligamentous
injury, as are follow-up visits for further treatment and rehabilitation.
The proper treatment of a grade III injury is still under debate
but should include a sling and an orthopedic follow-up visit within
72 hours.
Sternoclavicular joint dislocation. The SC joint
dislocation, in which the clavicle can be displaced anteriorly or
posteriorly, is the least common of all shoulder dislocations. Posterior
SC joint dislocations, although very rare, are usually associated
with other severe injuries, because the joint is so close to the
great vessels and the airway. The mechanism of injury is a direct,
forceful blow to the proximal clavicle. The diagnosis can be confirmed
by a radiograph taken in a 40° cephalic tilt; computed tomography
can also confirm the injury. Anterior dislocation of the SC joint
is also rare but much less likely to be associated with other injuries.
The mechanism is typically lateral compression of the shoulder.
Injury to the SC joint, which more commonly manifests as a sprain,
is also graded according to the extent of SC and CC ligament injury.
In a grade I injury, tears of the ligament are absent; patients
with this injury can be given a sling and analgesic therapy. Grade
II and III injuries involve varying degrees of injury to the ligaments
that make orthopedic referral necessary. Although anterior dislocations
can be reduced in the office or ED, most of these reductions will
be unstable and therefore necessitate an orthopedic consultation.
In the case of posterior SC joint dislocation, the role of the emergency
or primary physician is to identify and treat any associated injuries.
Such a dislocation should be reduced only in the operating room
with the patient under general anesthesia.
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Assessing the Dislocated Shoulder
The evaluation of shoulder dislocations, especially anterior ones,
is often clinical. An affected patient will present with a typical
history, often indicating previous dislocations, and will be holding
the affected arm in a characteristic manner. On physical examination,
the shoulder may have a lateral squared-off appearance, and the
deltoid muscle will show a loss of its normal rounded contour. Muscle
spasm may also be present, and the humeral head is often palpable
anterior to the glenohumeral joint.
A neurovascular assessment, as described earlier, is essential
before and after the joint is manipulated and should be well documented.
The nerve most likely to be injured in an anterior dislocation is
the axillary nerve, which is affected in 3% to 4% of such injuries.
A two-point discrimination test over the lateral deltoid muscle
is useful for detecting injury to this nerve.
Traditionally, patients in whom dislocation was suspected all underwent
radiography before and after a reduction procedure. A growing body
of evidence suggests, however, that in some circumstances obtaining
films both before and after reduction may not be necessary. For
patients whose dislocation is associated with blunt trauma, for
example, films obtained before reduction may reveal fractures associated
with the dislocation, but patients who have recurrent atraumatic
dislocations rarely have such associated fractures; for these patients,
films obtained before reduction are probably unnecessary.
Films obtained after a dislocation is reduced can confirm the reduction
and rule out a fracture caused by the reduction. Such films may
not be necessary, however, if the ones obtained before the reduction
are normal. Obviously, difficult or uncertain reductions necessitate
further radiography to rule out complications or persistent dislocation.
Patients who may have a shoulder dislocation should be administered
medication for any associated pain before they undergo radiography.
Such treatment is essential, not only to make them comfortable but
also to facilitate the joint reduction procedure. A short-acting
intravenous narcotic, such as fentanyl, and a benzodiazepine, such
as midazolam, can provide adequate analgesia and sedation to these
patients during the procedure without necessitating hours of observation
in the office or ED afterward. The medications must be administered
cautiously, however, because they produce a strong somnolent effect
that may persist after reduction has been accomplished and the painful
stimulus is eliminated. To counteract such effects, agents such
as naloxone and flumazenil should be readily available at all times.
Patients should also be monitored before and after the reduction
procedure.
Some practitioners inject lidocaine and bupivacaine into the joint
itself to reduce the pain. This strategy is thought to aid the reduction
procedure and provide analgesia for some time afterward. Results
of studies suggest that patients prefer parenteral sedation and
analgesia, however, and the process of injecting the anesthetic
into a distorted joint may be difficult for practitioners unaccustomed
to routine shoulder injections.
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Reduction Techniques
Many techniques are used to reduce shoulder dislocations, most
of which are well tolerated and associated with a success rate of
approximately 80% to 90% and few complications.
The most common method is based on traction and countertraction,
for which two staff members are necessary. Patients undergoing this
procedure must first be given adequate analgesia and muscle relaxant
therapy. One staff member applies countertraction by pulling on
a sheet placed around the patient's torso and under the arms. While
that person pulls in a direction opposite that of the dislocation,
the other person applies inline traction to the dislocated arm,
pulling slowly but firmly until the arm is felt to "pop" back into
place.
The Kocher maneuver involves traction, external and internal rotation,
and adduction of the humerus and, unlike most of the other techniques
used, is poorly tolerated by patients and is associated with a relatively
high complication rate. This method can no longer be recommended
as a routine option, particularly when so many other safer and better-tolerated
methods have been devised.
Liedelmeyer has suggested a kinder, gentler variation of the Kocher
maneuver (Journal of American College of Emergency Physicians, vol.
8, p. 528, 1979). The patient is first administered pain medication
and placed supine. The affected arm is then gently and slowly adducted
to the patient's side. The elbow is flexed to 90°, and slow
and gentle external rotation is applied. This procedure must be
performed very slowly, and without much force, to avoid the risk
of muscle spasm, which will make the reduction process uncomfortable
or impossible.
The Stimson, or hanging-weight, method is very well tolerated by
patients and is fairly easy to employ. It takes a significant amount
of time to perform, however, during which a staff member must stay
with the patient. The patient, having received adequate analgesia
and muscle relaxants, is placed prone on the bed, with the affected
arm hanging down off the side. No manipulation is used in this technique;
instead, 10 to 15 pounds of weight is hung on the affected arm at
the wrist. The patient remains in this position until 20 to 30 minutes
later, typically, when the shoulder uneventfully reduces itself.
The scapular rotation method is similar to the hanging-weight method
but requires slightly more expertise from the practitioner. In this
approach, the humerus is not manipulated; rather, the scapula is
manually rotated so that the glenoid moves down to reform the glenoid
joint. The procedure is begun with the patient placed prone and
the affected arm draped over the side of the stretcher. Again, adequate
analgesia and muscle relaxant therapy are required. Five to 15 pounds
of weight is then applied to the arm. As an alternative, an assistant
may apply gradual, increasing pressure on the affected arm in a
downward direction. To align the glenoid and the humeral head, the
practitioner slowly rotates the inferior tip of the scapula medially
with one hand while stabilizing the superior edges with the opposite
hand.
After any reduction procedure, the practitioner should perform
a second, well-documented neurovascular examination. He or she should
also examine the rotator cuff muscles thoroughly, especially in
an older patient, who is much more likely to have associated rotator
cuff tears. In some cases, it may be best to delay the evaluation
until the lingering pain and inflammation from the dislocation and
the effects of the medication abate.
Not all dislocations can be treated with closed reduction. Orthopedic
consultation will be necessary for any dislocation accompanied by
an associated fracture. Although some injuries of this type may
still be reducible without the aid of surgery, most will not and
therefore must be examined by an orthopedist before any manipulation
of the shoulder is attempted. Displaced fractures of the greater
tuberosity will almost certainly necessitate surgical repair, as
will fractures of the glenoid rim. Occasionally, even an apparently
uncomplicated dislocation will not be reducible as a result of the
interposition of soft tissue in the joint. A Hill-Sachs lesion can
cause a reduction to become unstable, especially if the injury is
present on more than 20% of the humeral head. Surgical repair may
be necessary in such cases to ensure the reduction is maintained.
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Orthopedic Follow-up
In all cases, the shoulder should be immobilized and adequate analgesia--usually
a nonsteroidal anti-inflammatory drug (NSAID)--administered. Patients
should follow-up with an orthopedist even when a dislocation is
uncomplicated. Because an associated injury such as a rotator cuff
tear may not be immediately obvious, reevaluation will be necessary
soon after the reduction procedure.
Recurrent dislocation is a common problem, particularly in young,
active patients. Bankart lesions, which are associated tears of
the glenohumeral ligaments, are becoming recognized as the most
likely cause of recurrent dislocation in general, but they are more
likely to occur in this group, in part because active young adults
have relatively stronger rotator cuff muscles. Bankart lesions necessitate
more immediate and aggressive surgical repair.
Orthopedic follow-up is also necessary in the treatment of recurrent
dislocation, in which surgical repair may eventually be an option.
After undergoing treatment, patients, particularly those who suffer
chronic shoulder instability and recurrent dislocation, should undergo
physical therapy to strengthen the rotator cuff muscles.
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Acute Pain Caused by Fracture
The possibility of fracture must be considered when a patient with
a history of trauma presents with acute shoulder pain. To properly
diagnose and treat such an injury, clinicians must be familiar with
the different types and causes of shoulder fracture.
Clavicle fracture. Clavicle fractures account for
5% of all types of fracture and are the most common type among children.
The break most often appears at the middle third of the bone and
is typically caused by a lateral blow to the shoulder from a tackle,
fall, or motor vehicle accident. The success rate regarding the
treatment of these fractures is excellent. Because reduction or
realignment of the bone is not normally necessary, clavicle fractures
of this type can usually be treated by primary care physicians and
heal remarkably well.
The treatment strategy includes pain control, immobilization of
the bone, and patient follow-up. Results of several studies have
shown that a simple sling is sufficient and can be an effective
alternative to a figure-eight brace, which is associated with more
complications and complaints from patients. Patients should wear
the sling until a series of films indicate evidence of callus formation.
The healing period usually lasts two to four weeks for younger children
and four to eight weeks for adolescents and adults. In adults older
than 20 years, a period of three months may be necessary before
the shoulder completely heals.
Clavicle fractures affecting the proximal or distal third of the
bone are more complicated. Together, fractures in the proximal and
distal third of the clavicle account for only 20% of clavicle fractures,
with the former representing only 5%. Proximal third injuries are
caused by a direct blow to the anterior chest wall and can be associated
with significant intrathoracic injuries. During the physical examination,
clinicians should therefore be especially alert for any signs of
pulmonary or neurovascular injury. The latter occurs rarely, but
immediate attention is necessary when it does.
Distal third fractures occur as a result of a direct blow to the
top of the shoulder. Type I fractures are nondisplaced fractures
in which the ligaments are intact. Type II distal fractures are
characterized by displacement and separation of the coracoclavicular
ligaments from the proximal fragment. Because many attempts to reunite
these elements usually fail, patients who have a type II distal
fracture should seek orthopedic follow-up within 72 hours of treatment.
A displaced fracture anywhere on the bone may produce severe tenting
of the skin, which must be addressed orthopedically to prevent necrosis
of the skin.
Young children sometimes have a clinical history and examination
findings that may suggest clavicle fracture, even though radiographs
may not reveal such an injury. In such cases, the injury is usually
a greenstick, or incomplete, fracture, for which sling immobilization
is the standard treatment. If pain or other symptoms persist, radiographs
should be obtained again 7 to 10 after the initial presentation.
Scapular fracture. A considerable force is necessary
to cause a scapular fracture, which is uncommon. Because the associated
injuries may be severe, scapular fracture is often missed during
initial trauma evaluation and treatment. Scapular fracture is highly
associated (incidence, 75% to 98%) with injuries to the ipsilateral
lung, chest wall, and shoulder girdle. Less common are injuries
to the brachial plexus and subclavian and axillary arteries. The
results of physical examination will reveal significant pain provoked
by movement; crepitus; hematoma; and "pseudorupture," a simulated
rotator cuff tear. Radiographs should reveal the fracture. A potentially
misleading element in the diagnostic image is the os acromion, which
is an unfused epiphysis of the acromion, occurring as a normal variant
in 3% of the population. It is present in both shoulders in 60%
of cases.
Usually, the treatment of scapular fracture includes conservative
therapy, analgesia, and sling immobilization for a period of two
to four weeks. Patients should begin a pendular shoulder exercise
regimen as soon they are able to tolerate it. Surgery is usually
necessary to treat a displaced acromial fracture that impinges on
the glenohumeral joint. In some cases, an acromion fracture may
be associated with a dislocation; invariably, the rotator cuff muscle
will have a tear as well, for which surgical repair is necessary.
Proximal humerus fracture. Fractures of the proximal
humerus are fairly common, accounting for 4% to 5% of all fractures.
They occur most typically in older patients, for whom the usual
cause is a simple fall on the outstretched arm in pronation, which
levers the head against the acromion. Younger patients suffer these
fractures as well, after more severe trauma. Overall, 85% of these
fractures are minimally displaced and respond well to conservative
therapy.
Displaced fractures may necessitate surgery, but significant displacement
is compatible with normal function. Such displacement is more likely
to occur in younger patients, whose stronger muscle mass pulls the
ends of the bone at oblique angles. Displacement is defined as angulation
of greater than 45º and separation of greater than 1 cm.
Nondisplaced fractures can be treated conservatively with sling
and swathe immobilization. Passive range of motion and pendular
shoulder exercises are important to prevent adhesive capsulitis.
The healing period lasts four to six weeks. Adhesive capsulitis
is the most common complication, especially among older patients.
Orthopedic consultation and follow-up are necessary for any displaced
humeral fracture or fracture/dislocation.
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Chronic Pain Caused by Rotator Cuff Tendonitis
Most patients who present to a primary care physician with shoulder
pain will have chronic pain. Overuse of the shoulder is very common
and can cause significant distress and disability. The most common
result of overuse is rotator cuff tendonitis.
Tendonitis of the muscles of the rotator cuff (supraspinatus, infraspinatus,
teres minor, and subscapularis) is common among those who perform
repetitive movements with their arms over their head, as might be
necessary in some occupations and activities. It is also common
among athletes who throw or swim. In about one third of cases, however,
the cause is not identifiable.
Rotator cuff tendonitis is a continuum of rotator cuff impingement,
tendonitis, and acute tears. In each of these injuries, the acromion
encroaches on the rotator cuff muscles, causing inflammation, microhemorrhage,
edema, fibrosis, and frank tendon rupture. The best imaging method
for evaluating the rotator cuff itself is magnetic resonance imaging
(MRI), which allows visualization of bony structures and soft tissues.
Shoulder arthrography and computed tomography may also be used,
but they do not permit visualization of the soft tissues as well
as MRI does.
The "painful arc." Patients who have a rotator
cuff disorder tend to present with indolent, progressive shoulder
pain that worsens during specific activities, especially those that
involve movements such as reaching forward or overhead. The pain
is usually more severe at night, particularly when a patient lies
on the affected shoulder. Patients may also note the pain is worst
when they move the affected arm through 60º to 120º of
abduction, the so-called painful arc. They usually have no history
of trauma and may or may not be able to pinpoint the onset of the
problem. One or both shoulders may be affected. Except when caused
by an athletic injury, these problems usually appear during a patient's
middle age or later.
Both shoulders should be exposed, examined, and compared. Atrophy
and loss of the normal shoulder contour may be evident in the case
of a chronic rotator cuff disorder. Palpation of the shoulder joint
will likely not reveal any point tenderness, although tenderness
may be noted over the lateral insertions of the rotator cuff tendons
at the greater tuberosity of the humerus. Often, deep palpation
of the shoulder is painful even in the absence of a disorder.
Signs of impingement. Specific signs of impingement
may be noted during the range of motion evaluation. The Neer impingement
sign, for example, is indicated by pain that occurs when the shoulder
is flexed forward to raise the arm above the head. The pain is produced
as the rotator cuff muscles are caught between the acromion and
the greater tuberosity of the humeral head. Hawkin's impingement
sign is pain produced by maximal internal rotation with the arm
at 90º of abduction. These signs are indicative of impingement,
subacromial bursitis, tendonitis, or rotator cuff tears.
Strength testing of the rotator cuff and associated muscles is
fairly straightforward. Specific maneuvers are used to test and
isolate each of the rotator cuff muscles.
The deltoid muscle is responsible for most of the range of the
arm's abduction (20º to 90º) and is assisted by the trapezius,
rhomboid, and supraspinatus muscles. Resistance to abduction, with
the arm at 90º and the thumb pointed down, isolates the supraspinatus
muscle and is used to detect weakness or pain. Such a response is
known as the empty can sign and is commonly seen in rotator cuff
impingement. The "hornblower's position" test is also indicative
of supraspinatus injury, which is revealed when a patient cannot
hold his or her arm in a position that one would use to hold a horn.
The infraspinatus, teres minor, and posterior deltoid muscles are
assessed by performing external rotation of the shoulder with the
arms at the sides and elbows flexed at 90º. An injury to one
or more of the shoulder muscles is indicated when a patient cannot
externally rotate the shoulder.
Internal rotation is primarily controlled by the subscapularis
muscle, the least commonly torn of all the rotator cuff muscles.
This muscle can be evaluated with the "lift-off" test, in which
a patient places the dorsum of the hand against his or her back
and attempts to lift the hand away from the back. (The subscapularis
cannot be isolated when the arm is placed at the patient's side
and the elbow flexed to 90º; the pectoralis muscle plays a
large role.) Subscapularis injury is indicated when the patient
cannot lift the hand.
In patients unable to perform the lift-off test, the subscapularis
can be isolated by first instructing the patient to place the palm
of one hand on his or her stomach with the elbow held close to the
body. The examiner then tries to pull the patient's hand away from
the stomach as the patient resists. This procedure limits the involvement
of the pectoralis muscle.
The long head of the biceps muscle may also be involved in rotator
cuff injury. The long head of the biceps courses across the bicipital
groove, under the anterior edge of the acromion. When tendonitis
is present, the biceps tendon is rarely affected by itself, as the
rest of the rotator cuff muscles are often involved. Tendonitis
can cause frank tears in the tendon, producing the classic "Popeye"
appearance of the muscle.
Acute tears of the rotator cuff muscle usually occur in patients
who have no history of shoulder pain and are usually caused by trauma,
forced abduction against significant resistance, a fall on an outstretched
arm, or the lifting of a heavy object. Affected patients will report
a sudden, tearing sharp pain, which may radiate down the arm to
the elbow. Significant muscle spasm is usually present, as is point
tenderness and occasionally a palpable defect in the muscle. Initially,
the range of motion will be decreased in response to the pain, but
even after the pain has subsided, the active range of motion will
remain limited, and some weakness may persist.
Large tears of the supraspinatus muscle hinder abduction of the
affected arm and produce weakness when the arm is rotated internally
at 90º degrees of abduction. The supraspinatus muscle is the
one most commonly involved in tears, but the other muscles may also
be affected. Radiographs will most likely be unremarkable, but occasionally
they may show elevation of the humeral head. The normal subacromial
space is 7 to 10 mm wide; a space less than 6 mm is indicative of
a rotator cuff tear. A definitive clinical diagnosis may have to
be delayed until the associated acute swelling and spasm to resolve.
Radiographic evidence can be obtained via MRI, ultrasonography,
or arthrography. The treatment strategy includes analgesia, immobilization,
and prompt orthopedic follow-up. Surgical repair within three weeks
of initial treatment often improves restoration of muscle function,
particularly in young, active adults.
Patients who have a long history of shoulder pain attributable
to rotator cuff tendonitis or subacromial bursitis are usually subject
to chronic tearing of the rotator cuff muscles. These patients are
typically men aged 40 years or older who have a history of performing
strenuous, repetitive movements with their arms over their head.
On physical examination, these patients may demonstrate significant
atrophy of the rotator cuff muscle and display compensatory scapulothoracic
movement to initiate abduction. Radiographs are likely to show chronic
degenerative changes. Elevation of the humeral head is also likely
to be noted. Treatment includes analgesia, NSAID therapy for inflammation,
orthopedic follow-up, and possibly subacromial steroid injections.
Outpatient physical therapy is also important for these patients.
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Other Causes of Chronic Shoulder Pain
The patient with persistent shoulder pain may be suffering from
the enigmatic "frozen shoulder" or from calcium deposits in the
rotator cuff.
Adhesive capsulitis. A poorly understood condition,
adhesive capsulitis is also known as frozen shoulder, because it
is characterized by a loss of range of motion. The disorder is most
often triggered by overuse or an injury that immobilizes the shoulder.
In such cases, the loss occurs when the muscles, ligaments, and
joint capsule itself lose their ability to flex and stretch. Some
patients, however, may not have a history of immobilization or of
any other identifiable cause.
Adhesive capsulitis affects more women than men, particularly women
aged 40 to 60 years, and usually occurs in the nondominant arm.
When no clear cause can be discerned, the disorder is often associated
with diabetes, hypothyroidism, and even mental illness. Treatment
includes NSAID therapy, intra-articular steroid injections, and
physical therapy. Some patients may benefit from manipulation of
the shoulder, while under general anesthesia, to reestablish flexibility
of the joint.
It is extremely important to distinguish this disorder from a posterior
dislocation. The clinical presentation may be very similar, and
radiographs may be necessary to elucidate the true cause of the
problem. A mistake in the diagnosis can spell trouble for the patient.
A missed posterior dislocation can lead to long-term shoulder problems,
whereas a frozen shoulder misdiagnosed as a dislocation can lead
a clinician to perform an unnecessary and potentially harmful reduction
of a normal shoulder joint.
Another disorder included in the differential diagnosis of frozen
shoulder is polymyalgia rheumatica. Although both disorders share
some similar symptoms, polymyalgia typically affects both shoulders,
whereas frozen shoulder does not. The difference between the two
can be discerned from the elevated erythrocyte sedimentation rate
seen in polymyalgia, in association with particular findings in
a patient's medical history, such as age over 50 years, joint effusion,
and proximal joint arthritis.
Calcific tendonitis. Calcific tendonitis is caused
by calcium deposits that form and are resorbed in the rotator cuff
tendons, most commonly those of the supraspinatus muscle. Most affected
patients are between 30 and 40 years old; the disorder is rarely
seen in patients younger than 30 or older than 60 years. This condition
occurs in three phases: a silent, subacute, and acute phase. The
silent phase is normally detected as an incidental finding on a
radiograph. Symptoms are not evident in this stage, the length of
which is highly variable. The calcium deposits are well defined
and show no evidence of surrounding inflammation or irritation.
The second, subacute phase is characterized by pain and limited
range of motion. The appearance of the calcium deposits on films
is a mixture of the sharp-edged, noninflammatory deposits observed
in the silent phase and the cloudy, more transparent deposits seen
in the acute stage.
Most patients present to a physician during the acute phase. This
last phase is accompanied by severe shoulder pain and a further
decrease in range of motion; the pain and weakness may occur at
night as well. The radiographic appearance of the calcium deposits
is notably different during this phase. They resemble an abscess,
with cloudy edges, and the associated inflammation is obvious. The
pain during this phase is thought to be caused by the inflammatory
reaction and is accompanied by the resorption of the deposits. On
physical examination the shoulder may be warm and very tender.
An AP view of the shoulder, with the affected arm in internal and
external rotation, provides the best radiographic confirmation of
calcific tendonitis. This view allows adequate visualization of
the supraspinatus, which is the most commonly involved tendon. The
other rotator cuff muscles may be involved, however, and these can
be visualized on an axillary lateral view.
The cause of this disorder is not known, but it usually resolves
spontaneously within a few weeks. The standard treatment consists
of immobilization, NSAID therapy, and subacromial injections. For
patients who present during the acute phase of the disease, an intra-articular
injection of lidocaine and a steroid should restore full range of
motion. To prevent frozen shoulder during the period of immobilization,
patients should perform gentle range of motion exercises. Occasionally,
the intensity and duration of the pain may be severe enough to warrant
surgical treatment. A needle can sometimes be used to rupture the
deposits, with or without the aid of fluoroscopy. Arthroscopy can
be also be used to remove the deposits.
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