The acromio-clavicular joint (AC joint) is a small joint in the shoulder between the acromion process of the scapula (shoulder blade) and the clavicle (collar bone). It is typically injured when a sizeable force is directed onto the tip of the shoulder, usually as a result of a fall onto the shoulder. AC joint dislocations and injuries are hence common in athletes who engage in sports like cycling, roller blading, skateboarding, as well as in athletes who engage in contact sports like rugby and American football. It is also common in motorcyclists involved in road traffic accidents and falling off their bike.
Patients with AC joint dislocation or injury will typically report a fall onto their shoulder. They will notice pain. stiffness and swelling around the tip of the shoulder. When the dislocation is severe, patients may also notice a ‘step deformity’ of the shoulder, which is not present in the opposite shoulder.
Assessment of the shoulder by your doctor will include a routine examination. A series of x-rays will usually clinch the diagnosis of an AC joint dislocation.
Treatment of AC Joint Dislocation
Not all AC joint injuries and dislocation require surgical reduction. The majority of low grade injuries and dislocation can be treated non-operatively with a sling and a course for physiotherapy, and gradual return to normal activities from 6 weeks to 3 months.
Surgery is reserved for high grade separations, usually in the setting of a high demand and active individuals. There is clinical evidence that high grade AC joint dislocation in active individuals do better in terms of shoulder function with surgery than when treated non-operatively.
AC joint fixation is typically done as a day surgery, under general anaesthesia. The joint is exposed and a medical device in the form of a metal plate or a suspensory device is used to reduce the AC joint dislocation. Some of these metal devices may require removal 3 to 6 months down the road.
Minimally Invasive Techniques
There has been a recent push towards more minimally invasive ways of doing this surgery with the same efficacy and safety. This minimally invasive technique is known as the arthroscopic assisted AC joint fixation. The technique utilises a keyhole arthroscopy technique to achieve reduction and fixation. The joint is typically held reduced with a suspensory fixation device. The benefits of this technique, other than cosmetic reasons, are:
- the ability to use the arthroscope to look for associated injuries within the shoulder joint which is often missed with the open technique
- faster recovery for an earlier return to activity as a result of less damage and muscle takedown as we perform the surgery.
The minimally invasive and low-profile suspensory device used to maintain the joint reduction in this key-hole technique also does not require subsequent removal.
Recovery from AC Joint Dislocation
Most patients will use a sling for about 4 to 6 weeks after surgery. Using the minimally invasive arthroscopic technique, we will start physiotherapy immediate after surgery, and allow pendular exercises for the 1st 2 weeks. We will then allow passive range of motion for the next 4 weeks. Once the sling is taken off after 6 weeks, we will allow full range of motion exercises. Normal routine daily activities should be achievable by this time. Return to sport or active upper limb activity will usually be allowed at about 3 to 6 months after surgery.