Rotator Cuff Clinical Presentation.
Last updated Wednesday, January 26, 2005
Weakness
Weakness or pain on muscle contraction limits the function of the shoulder with cuff disease.More about weakness Tendon fibers weakened by degeneration may fail without clinical
manifestations or may produce only transient symptoms interpreted as
"bursitis" or "tendinitis." A greater injury is required to tear the
cuff of individuals at the younger end of the age distribution.
Traumatic glenohumeral dislocations in individuals over the age of 40
have a strong association with rotator cuff tears. These traumatic cuff
tears commonly involve the subscapularis, producing weakness in
internal rotation. Neviaser et al (Neviaser, Neviaser, 1993) reported
on thirty-seven patients older than 40 years of age in whom the
diagnosis of cuff rupture was initially missed after an anterior
dislocation of the shoulder. The weakness from the cuff rupture was
often erroneously attributed to axillary neuropathy. Eleven of these
patients developed recurrent anterior instability that was due to
rupture of the subscapularis and anterior capsule from the lesser
tuberosity. None of these shoulders had a Bankart lesion. Repair of the
capsule and subscapularis restored stability in all of the patients
with recurrence.
Sonnabend reported a series of primary shoulder dislocations in
patients (Sonnabend, 1994) older than 40 years of age. Of the 13
patients who had complaints of weakness or pain after 3 weeks, eleven
had rotator cuff tears. Toolanen found sonographic evidence of rotator
cuff lesions in 24 of 63 patients over the age of 40 years at the time
of anterior glenohumeral dislocation. (Toolanen, Hildingsson, 1993) Manifesting weakness Even though patients with full thickness cuff defects may still
retain the ability to actively abduct the arm, (Neviaser, 1971)
significant tendon fiber failure is usually manifest by weakness on
manual muscle testing. (Brems, 1987 Jan, Hawkins, Misamore, 1985,
Leroux, Codine, 1994, Leroux, Thomas, 1995) Isometric testing of muscle
strength prevents confusion with symptoms which may arise from shoulder
movement (such as those associated with subacromial abrasion). While
the individual cuff muscles cannot be specifically isolated the
following isometric tests are reasonably selective (see figure 6):
- supraspinatus: isometric elevation of the arm held in 90 of elevation in the plane of the scapula and in mild internal rotation.
- subscapularis: isometric internal rotation of the arm with the
elbow flexed to 90 and the hand held posteriorly just off the waist.
- infraspinatus: isometric external rotation of the arm held at the side in neutral rotation with the elbow flexed to 90.
These simple manual tests are helpful in characterizing the size of
the tendon defects, from single tendon tears involving only the
supraspinatus, to two tendon tears involving the supra and
infraspinatus to three tendon tears involving the subscapularis as
well.
Individuals with partial thickness cuff lesions have substantially
more pain on resisted muscle action than those with full thickness
lesions. This phenomenon is analogous to the observation that partial
tears of the Achilles tendon, partial tears of the patellar tendon, and
partial tears of the origin of the extensor carpi radialis brevis are
more painful on muscle contraction than when the complete structure is
ruptured or surgically released. Fukuda and coworkers (Fukuda, Mikasa,
1987) characterized patients with partial-thickness cuff tears as
having pain on motion, crepitus, and stiffness. They observed that
patients with bursal side tears seemed more symptomatic than those with
deeper tears, due to the resulting problems with roughness of the
articulation between the upper surface cuff and the under surface of
the coracoacromial arch.
Some have suggested that weakness from pain inhibition can be
distinguished from weakness from tendon defect by a subacromial
injection of local anesthetic. (Ben-Yishay, Zuckerman, 1994, Lindblom
and Palmer, 1939) If cuff dysfunction has been present for more than a
month or so, it may be accompanied by supraspinatus and infraspinatus
muscle atrophy. Subtle atrophy can be seen most easily by casting a
shadow from a light over the head of the patient. Defects in the cuff As pointed out by Codman (Codman, 1934b) defects in the cuff can often
be palpated by rotating the proximal humerus under the examiner's
finger placed at the anterior corner of the acromion. The perimeters of
the "divot" left by a defect in the supraspinatus are particularly easy
to palpate. The defect is usually just posterior to the bicipital
groove and medial to the greater tuberosity.
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