“I have shoulder impingement because there isn’t enough space between the bones.” This is called the sub-acromial space and it has long been touted as a reason for shoulder impingement syndrome and even the shape of the acromion process has been spoken about for the cause. The thinking is that because the space is smaller then this increases the risk of shoulder pain from impingement. However, does a smaller sub-acromial space in the shoulder cause shoulder pain and impingement?