AC joint injuries can occur due to:

• Fall on an outstretched hand or elbow
• Direct trauma to the lateral shoulder or acromion process with the arm in adduction.

These injuries account for 9 % of total shoulder girdle injuries. These are very common in athletic population and can account for 40 to 50 % of shoulder injuries in several contact sports.

The AC joint injuries are diagnosed based on patient’s history of injury, clinical examination of the shoulder region and appropriate investigations.

Patient develops pain, swelling, bruising and may have bump deformity around the top of the shoulder. They have difficulty with overhead activities. The is tenderness over the AC joint and painfully limited shoulder mobility.

X-rays of the shoulder can show AC joint injuries with any associated fractures. This helps in diagnosing the AC joint injury and also establishing its severity.

CT scan and MRI scan are very rarely needed for making a diagnosis.

There are various types of classifications for AC joint injuries. The severity of these injuries depends upon the severity of the damage to its stabilising ligamentous tissues. Injury to AC ligaments is not considered serious but injuries to CC ligament affect the whole shoulder girdle and hence are considered serious. There are six grades of AC joint injuries.

Type I:      Sprain of the AC ligament. The AC or CC ligaments are intact.

Commonest injury

Type II:    Tear of the AC ligament. CC ligaments intact.

Type III:   Both the AC & CC ligaments are torn. There can be 25% to 100%

displacement of the clavicle compared to opposite side.

Grades IV to VI are uncommon and occur due to high energy injuries like motor vehicle accidents. These injuries are serious ones and normally need surgery.

AC joint injuries are most commonly treated conservatively.  

• Patients are given a shoulder pouch that supports the elbow. It provides support and helps reduce pain. The shoulder pouch may be needed for 2 to 3 weeks until the pain settles down.

Surgical treatment is advised for AC joint injury if there is:

• Failure to respond to conservative treatment
• Ongoing pain or instability even after 3 months with overhead activities in sportsmen.
• Young patients involved with contact sports & heavy manual work.

There are several surgical techniques for stabilisation of the AC joint.

The most commonly performed surgery involves reconstruction of the coracoclavicular ligaments with a hamstring tendon graft and excision of the lateral end of the clavicle. The graft could be reinforced with specialised suture tapes. These surgeries can be done arthroscopically assisted or with open technique.

The outer 10 -15 mm of the clavicle is excised and then the AC ligament is transferred from the bottom of the acromion into the cut end of the clavicle to replace the torn ligament.

The complications associated with AC joint injuries are:

• Persistent cosmetic deformity
• Persistent instability of the shoulder girdle
• Pain at the AC joint
• Difficulty with overhead activities during contact sports and work
• Failure of fixation devices used for stabilisation of AC joint
• Scar hypertrophy
• Damage to blood vessels and nerves
• Development of AC joint arthritis