The subacromial space is a physical space that exists between the acromion and the rotator cuff. This space can be compromised by congenital deformity of the acromion and/or by degenerative changes of the acromion and acromioclavicular joint. These changes in the skeletal morphology of the acromiohumeral space result in physical damage to the rotator cuff from the bone 'impinging' on it.
The symptoms associated with this condition cause shoulder pain, pain with overhead elevation, and pain at night with sleeping and shoulder weakness.