The acromio-clavicular joint is the connection between the collar-bone and the shoulder blade. When there is downward force applied to top of the shoulder blade, the ligaments holding this joint together will tear, causing a separation between the two bones. This is completely different from a dislocated shoulder, when the upper arm comes out of the shoulder socket.
After a shoulder separation a patient will commonly feel widespread pain, especially at night. Over time the pain will localize at the tip of the collarbone, often forming a step-like deformity. You will also find widespread weakness of the shoulder muscles along with swelling. These injuries are graded 1-6, depending on the extent of damage to the shoulder ligaments. Grades 1 – 3 can be treated conservatively with rehab, while Grades 4 – 6 usually require surgery.
Check back next week for how to treat shoulder separations: