Often I am asked by my patient’s and frequently by other patients as a second opinion, whether they need surgery after a dislocation of the acromioclavicular joint of their shoulder.
We will refer to the acromioclavicular joint as the AC joint.
The answer as to whether surgery is needed for an injury of this type is quite straightforward.
Mostly surgery is not needed. The decision really is made depending on the type and extent of the dislocation. A dislocation is when a joint is entirely out of position. A subluxation is when a joint is partly out of position.
Dislocations and subluxations of the AC joint are divided into 6 categories.
Type 1: This is the simplest type injury. It is a relatively minor sprain. The AC joint remains in place and is not subluxed or dislocated.
Type 2: Here there is some displacement of the joint. One of the 2 major ligaments of the joint are torn (the acromio-clavicular ligament)
Type 3: Here there is more significant displacement of the joint. The edge of the clavicle is displaced above the level of the adjacent acromion bone. There is therefore quite wide separation of the joint. Here both of the major ligaments are torn (the acromioclavicular ligament and coracoclavicular ligament). The capsule of the joint is also torn
Types 4, 5 and 6: Here there is far more major damage to the associated soft tissues and the AC joint is very widely displaced. In type 4 it displaces backwards or through the trapezius muscle, in type 5 it displaces far upward (much more than type 3) and in Type 6 it displaces far downwards (this is the only type where clavicle goes downward)
Most AC joint injuries are types 1 and 2. Type 3 is common. Types 4 to 6 are quite uncommon.
Surgery is never needed for a type 1 or 2 injury. They both heal within 3 to 12 weeks and symptoms settle by then but may linger for a further few months.
Surgery is hardly ever needed for a type 3 injury. The injury heals within 6 to 12 weeks, symptoms settling, but leaving an obvious bump on the shoulder which is not painful. The only reason for surgery is if the pain persists or the joint continues to feel unstable. Most people with a type 3 injury do not come to surgery.
Surgery is always offered for Types 4, 5 and 6 injuries.
Long term, most people do well no matter which of these injuries they suffer. But any injury to the AC joint, even the benign type 1, may develop complications many years later (degenerative changes); type 1 is the least likely to develop later complications. In most cases complications do not occur. If painful degenerative changes do develop years later then this can be dealt with simply with an arthroscopic procedure.
