The acromio-clavicular or “AC joint” spans the end of the clavicle and the acromion on the lateral side of the shoulder. Injury occurs from a direct impact to the shoulder. AC separations are classified based on the direction and magnitude of the dislocation and are commonly referred to as a “separated shoulder”. Low grade dislocations heal uneventfully with rest and immobilization. High grade separations with complete dislocation of the clavicle present with marked deformity at the joint. Historically these injuries have been problematic because of the inability to maintain alignment of the joint. Newer surgical techniques and implants allow more of these injuries to be repaired with good cosmetic and functional results.
If surgical treatment is indicated there are two choices for fixation, a hook plate and a suture based reconstruction of the torn ligaments. If the end of the collar bone is fractured in conjunction with an AC joint separation, the surgical choice is usually a hook plate which spans the lateral aspect of the clavicle and ‘hooks’ under the acromion. This implant works well clinically and the plate is able to hold the joint well reduced. The problem with these plates, however, is that they irritate the rotator cuff tendons especially with overhead movements and typically require removal at 3-6 months.
Both the Hook Plate and suture based reconstruction work well with a good functional and cosmetic outcome long term. There have been reports of failure with both types of fixation and this is dependent on factors such as the quality of the bone, the length of time between injury and surgery and smoking-which significantly increases the rate of failure of the implant.
The surgery to repair the AC joint is done on an outpatient bases, so the patient may return home on the day of the procedure. The anesthesiologist typically performs an inter-scalene nerve block (a type of regional anesthesia that numbs the shoulder area and arm) to help with post-operative pain control. The surgery takes about an hour and most patients report mild to moderate pain that requires pain medication for the first 2 weeks. Patients remain in a sling for the first 2 weeks after surgery and the rehab is similar to a subacromial decompression. Click here to see a post-op surgery protocol. Patients will not likely return to competitive athletics for 3-4 months after the surgery to avoid re-injury.