AC joint problems
The AC joint is located at the tip of the shoulder where the acromion portion of the shoulder blade (scapula) and collarbone (clavicle) join together. The AC joint is not as mobile as the large main shoulder joint and only moves when the shoulder is overhead or across the chest (adducted). The joint is partly filled with a thick pad of cartilage, known as the meniscus, wich allows the joint to move. The AC joint is stabilised by its capsule and additional ligaments (coraco-clavicular ligaments).