Subacromial impingement syndrome (SAIS)
is the most common disorder of shoulder,
accounting for 44-65% of all complaints of
shoulder pain during a physician’s office visit.
1
SAIS encompasses a spectrum of subacromial
space pathologies including partial thickness
rotator cuff tears, rotator cuff tendinosis, calcific
tendinitis, and subacromial bursitis. The
main consequences of SAIS are functional loss
and disability.
2
Subacromial space is defined by the humeral
head inferiorly, the anterior edge and under
surface of the anterior third of the acromion,
coracoacromial ligament and the acromioclavicular
joint superiorly. The height of space
between acromion and humeral head ranges
from 1.0 to 1.5 centimeters as seen on radiographs.
Interposed between these two
osseous structures are the rotator cuff tendons,
the long head of the biceps tendon, the
bursa, and the coracoacromial ligament. Any
abnormality that disturbs the relationship of
these subacromial structures may lead to
impingement.
3
Neer described three stages of impingement.
4 Stage-I impingement is characterized
by edema and hemorrhage of the subacromial
bursa and cuff. It is typically found in patients