Wc. Burns et Tl. Whipple, ANATOMIC RELATIONSHIPS IN THE SHOULDER IMPINGEMENT SYNDROME, Clinical orthopaedics and related research, (294), 1993, pp. 96-102
Impingement syndrome of the shoulder may be produced by compression of
the subacromial structures against the coracoacromial arch. The anter
ior tip of the acromion, the coracoacromial ligament, and the coracoid
process have been implicated as sources of impingement. Anatomic spec
imens were examined to determine the anatomic sites on the coracoacrom
ial arch that result in compression of the subacromial structures duri
ng specific shoulder motions that are known to produce impingement pai
n. The relationships of the supraspinatus tendon, the biceps tendon, a
nd the greater tuberosity of the humerus with the coracoacromial arch
were demonstrated through various arcs of shoulder motion in autopsy s
ubjects. Biceps tendon impingement occurred predominantly against the
lateral free edge of the coracoacromial ligament. Impingement of the s
upraspinatus tendon and greater tuberosity was demonstrated primarily
against the acromial end of the coracoacromial ligament and the anteri
or tip of the acromion during arcs of flexion and internal rotation. T
he coracoacromial ligament was stretched by the greater tuberosity pas
sing beneath it. This may explain the formation of traction osteophyte
s on the anterior acromion in patients with chronic impingement sympto
ms.