- Discussion:
- impingement syndrome describes pain in subacromial space when the
humerus is elevated or
internally rotated;
- during humeral flexion, the supraspinatus tendon and bursa become
entrapped between
the anteroinferior corner of the acromion (and CA
ligament) and the greater tuberosity;
- this syndrome is thought to precipitate attritional changes in
the rotator cuff, leading to
RTC tear;
- once the supraspinatus (and
infraspinatus) tendon is disrupted there will often be
further impingement and irritation which can lead to biceps tendonitis and
subsequent rupture;
-
differential diagnosis:
-
staging of impingement syndromes:
- outlet impingement:
- rotator cuff and
subacromial
bursa can be impinged between the greater tuberosity and the:
- anterior 1/3 of acromion:
- greater tuberosity impinges anteriorly w/ forward flexion and laterally along
undersurface of the acromion with modest abduction and neutral rotation;
- similar phenomenon can occur after displaced AC separations;
- coracoacromial ligament:
- forced internal rotation in forward flexed position will drive greater
tuberosity against the CA ligament;
-
AC joint:
- AC arthritis or AC joint osteophytes can result in impingement and mechanical
irritation to the
rotator cuff tendons;
- misc causes:
- greater tuburosity fractures can cause impingement on the rotator cuff if the
fragment
rotates superiorly;
- humeral neck fractures that heal in a varus position will cause the greater
tuberosity to tilt
more superiorly;
- coracoid impingement:
- pain is lower and more anterior than with superior impingement;
- look for decreased horizontal adduction with pain similar AC disease, but the
pain is at tip
of the coracoid and not AC joint;
- subscapularis tendon and biceps
degeneration and partial tearing are associated with this
type of impingement;
- non-outlet impingment:
- loss of normal humeral head
depression by the rotator cuff tear or weakness from a
C5-6 lesion
or suprascapular nerve palsy, or biceps tendon rupture;
- may occur due to thickening
or hypertrophy of the subacromial bursa and rotator cuff tendons;
- may occur in the
throwing athlete
due to posterior impingement;
- in these cases, patients may demonstrate excessive external rotation and/or
recurrent
anterior instability;
- references:
- Posterior
Capsular Contracture of the Shoulder
-
Arthroscopic capsular release for painful throwing shoulder with posterior
capsular tightness.
- Clinical Findings: (see
shoulder
exam)
-
staging of impingement syndromes:
- pain will often become worse at night, as the subacromial bursa becomes
hyperemic after a day of activity;
-
impingement test is performed by 1st eliciting positive impingement sign;
- impingment sign: pain which occurs after forward flexing arm to 90
deg, and forcefully internally rotating
the shoulder;
- 10-15 ml of 1% xylocaine are the injected into the
subacromial
space, and the impingement sign is
again sought;
- subacromial space should not be injected with steroids twice,
because of the risk of tendon rupture;
- carefully test for shoulder contractures:
- patients w/ contracture of posterior capsule (and loss of IR) will
be most likely to demonstrate signs
of impingement (despite normal acromial
anatomy);
- ref:
Quantification of Posterior Capsule Tightness and Motion Loss in Patients with
Shoulder Impingement
-
Radiographic Classification:
-
30 deg caudal tilt AP view
- this is perhaps the most important radiographic study since it shows
the anterior proliferation of the anterior
acromion relative to the clavicle (which cannot be determined
from the outlet radiograph);
-
scapular outlet view
- Non-Operative Treatment:
- as noted by D.S. Morrison et al 1997, 2/3 of patients can expect to have
significant relief of symptoms with
non operative treatment;
- only half of patients who are over 60 years of age will have
satisfactory result with non operative treatment;
- 91% of patients w/ a type I acromion will have satisfactory result;
- patients should specifically work on increasing specific deficits in their
ROM such as loss of internal
rotation (as compared to the normal side);
-
specific techniques:
- IR is improved by having the patient reach the good hand behind his
neck and and simultaneously
place his painful side in maximal IR up the back;
- a towel or a rope is used to connect the two hands, and the
good hand raises up to celing, forcing
the other into maximal internal rotation;
- flexion is improved on by use of overhead pulleys and use of a meter
stick;
- Operative Treatment:
- cases that do not respond to above conservative measures after 6 months of
treatment are candidates for
surgery;
- choices include
open
acromioplasty or
arthroscopic acromioplasty;
- note that Rockwood has expressed concern about arthroscopic
decompression because it disrupts
the lower half of the deltoid origin to the
deltoid;
- while this concern has not been borne out by clinical
studies, it may be an important consideration
for type III acromions, since an
adequate decompression would require an extension amount of
deltoid detachment both inferiorly and anteiorly;
-
preoperative considerations:
- be clear with the patient about the expected results of surgery;
- if the patient demonstrated excessive pain from the
subacromial steroid injection
(at the time of injection), then it is likely that
the patient will demonstrate excessive postoperative pain;
- likewise, if the results of the steroid injection did not
provide significant relief, then a decompression
may not satisfy the patient's
expectations;
-
cautions:
- in the case of
massive rotator cuff tear, an acromioplasty (w/ CA ligament release) may
precipitate
additional superior migration;
- throwing athelets w/ impingment often do not benefit from
acromionplasty;