- Diff Dx:
    - C5-C6 lesion
    - suprascapular nerve palsy
    - biceps tendon rupture
    - biceps tendonitis
    - calcific tendinitis:
    - traumatic tear of rotator interval;
         - this lesion will demonstrate extension of dye into subacromial space;
    - axillary nerve palsy:
         - may occur from previous shoulder dislocation or iatrogenic injury;
         - will cause both deltoid and teres minor injury;
    - os acromiale:
    - posterior (internal) impingement: (see throwing shoulder)
    - polymyalgia rhematica
    - parsonage turner syndrome