Rotator
Cuff/Impingement
Rotator Cuff Anatomy
The
rotator cuff is composed of the tendinous portions of four muscles: the
supraspinatus, infraspinatus, teres minor and the subscapularis. The rotator cuff acts as a major stabilizer
to the glenohumeral joint. The cuff
musculature provides dynamic stability to the glenohumeral joint, keeping the
humeral head within the shallow glenoid cavity during shoulder range of
motion. The innervation, major blood
supply and primary action of the rotator cuff muscles are listed in Table I.
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Impingement/Rotator Cuff Disease
Impingement
is a term used to describe shoulder pain related to a decreased subacromial
space with abutment of the greater tuberosity and the inferior acromion. A hooked acromial shape and formation of
inferior acromion spurs are both associated with classic outlet
impingement. Impingement of the rotator
cuff has been classified into three stages: initial inflammation and edema (I),
tendonitis (II), and tearing of the rotator cuff (III).
Classic impingement caused by a mechanical narrowing
within the subacromial space usually occurs in patients around forty years and
older and is rare in the younger population.
However, impingement has been described in the young, athletic
population, particularly in overhead athletes.
This is referred to secondary impingement. The pathology of secondary impingement is related to microtrauma
of the glenohumeral static restraints from repetitive activities. The injury to the shoulder static restraints
increases glenohumeral translation and can cause impingement symptoms.
Rotator cuff tears, much like impingement, occur most
frequently in patients over forty years old.
Rotator cuff tears are multi-factorial in nature and can be caused by
mechanical (impingement, overuse) or age-related (tendon degeneration, delayed
healing ability, poor vascularity) pathology.
It has been estimated that after the age of 40, up to 30% of patients
may have a rotator cuff tear. After the
age of 60, up to 80% of patients may have a rotator cuff tear. Although rare, rotator cuff tears may occur
in the younger population usually secondary to a direct blow to the shoulder or
repeated overhead activities.
History
Most
patients with rotator cuff pathology will complain of anterior shoulder pain
and difficulty with overhead activities.
Patients with rotator cuff tears often complain of night pain. They may complain of stiffness and weakness
as well.
Physical Exam
The physical exam of the rotator cuff should begin with
inspection, palpation, evaluation of passive and active range of motion and
strength testing. Inspection may reveal
atrophy of the supraspinatus and infraspinatus. Often patients with rotator cuff pathology have tenderness
anterior and lateral to the acromion.
Active and passive range of motion is important since patients with
rotator cuff tears often have decreased active motion compared to passive
motion.
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Isolation of infraspinatus |
Isolation of supraspinatus |
Gerber lift-off test |
The
primary function of the supraspinatus is to abduct the shoulder concurrently
with the deltoid. The optimal position
for isolated strength testing of the supraspinatus is at 90º of elevation and
45º of external rotation.
The infraspinatus and teres minor are primary external
rotators of the shoulder. The optimal
position for infraspinatus strength testing is at 0º elevation and 45º internal
rotation.
The subscapularis is primarily an internal rotator of the
shoulder. One method of isolating
the subscapularis is by performing the lift-off test. The lift-off test is performed by placing the hand in the mid-lumbar
region and the patient is asked to lift the hand off the back. Weakness of the subscapularis is noted with
the inability to bring the hand away from the back. The belly press test is another way to assess subscapularis function.
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Neer Test |
Hawkins Test |
Imaging
Imaging
begins with radiographs of the shoulder.
The typical shoulder series includes at least an anteroposterior, scapular
Y, and axillary radiograph. With large
rotator cuff tears the humerus may be “high riding” with a decreased acromiohumeral
distance. Degenerative changes in
the glenohumeral joint may also be seen in chronic cuff tears.
The axillary image is used to evaluate the glenohumeral joint space
and the scapular Y view is primarily used to assess the acromion morphology.
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Scapular
Y view with hooked acromion |
MRI with
rotator cuff tear |
Imaging of the rotator cuff musculotendinous unit can be
assessed by shoulder arthrogram, MRI and ultrasound. All three studies can be helpful in the assessment of rotator
cuff tears.
Treatment
Treatment of shoulder impingement begins with
non-operative measures. Physical
therapy consisting of a stretching and strengthening program is the first line
of treatment. Non-steroidal medication
may be used to decrease inflammation.
Cortisone injections into the subacromial space may also be used to
decrease inflammation.
If conservative measures do not relieve the impingement
symptoms, an acromioplasty may be performed.
The anteroinferior acromion and coracoacromial ligament are removed to
widen the subacromial space. Both open
and arthroscopic acromioplasty techniques have been shown to be beneficial in
treating impingement.
Symptomatic rotator cuff tears may be treated
surgically. Partial tears of the
rotator cuff are treated with debridement vs. excision and repair of the
tendon. General recommendations for the
treatment of partial tears are debridement for tears involving less than 50% of
the tendon thickness and excision and repair for tears involving greater than
50% of the tendon thickness.
Symptomatic full thickness tears should be repaired if possible. This can be done with arthroscopic or open
techniques. Some massive tears cannot
be fully repaired. Surgical options for
massive irreparable tears are medialization of the cuff, superior transposition
of the subscapularis, patching the defect with tissue or synthetic material,
and latissimus transfer.
