An AC Joint Dislocation is an injury to your acromioclavicular joint.
Your acromioclavicular joint is located at the top of your shoulder and is where your shoulder blade (scapula) meets the end of your collarbone (clavicle).
An AC Joint Dislocation is a stretch or tear of one or more of the ligaments that hold the joint in place. When the ligament tears, your collarbone may move out of its normal place and stick up under the skin just below your shoulder.
Surgery is usually not required. Instead, conservative treatment — such as rest, ice and pain relievers — is often enough to relieve pain. Most people regain full shoulder function within a few weeks after experiencing an AC Joint Dislocation.
Also known as
- Shoulder separation
- Acromioclavicular (AC) separation or sprain.
Symptoms
Signs and symptoms of a separated shoulder may include:
- Shoulder pain (severe at the moment of injury)
- Shoulder or arm weakness
- Shoulder bruising or swelling at the top of the shoulder
- Limited shoulder movement
- A bump at the top of your shoulder
Causes
The top of your shoulder blade (acromion) meets the end of your collarbone (clavicle) at the acromioclavicular (AC) joint. In an AC joint dislocation, the ligaments that make the joint stable are stretched or torn, resulting in a separation of the two bones and a bump at the top of the shoulder.
How does it occur?
An AC Joint Dislocation can result from a blow or fall on your shoulder. It also can result from a fall on your outstretched hand or arm. It is a common injury in contact sports such as football, rugby, hockey, or lacrosse. It may happen during downhill skiing, volleyball, rock climbing, and soccer.
Risk Factors
If you’re at risk of falling on your shoulder, you’re at risk of a separated shoulder. The risk is particularly high for athletes — especially those who participate in contact sports, such as football and hockey, and in sports that may involve falls, such as downhill skiing, gymnastics and volleyball.
Investigations
Often, a separated shoulder can be identified during a physical exam. Your doctor may use an X-ray of the shoulder or other imaging studies to confirm the diagnosis and study the extent of the injury.
A separated shoulder is graded depending on how far your collarbone is separated from your shoulder:
- Type I. You may have discomfort but not actual separation.
- Type II. There’s a slight separation.
- Type III. Both the acromioclavicular and nearby coracoclavicular ligaments are completely torn.
- Types IV, V and VI. These are the most severe tears, and they often require surgery.
How is it diagnosed?
Your healthcare provider will examine your shoulder for tenderness and a bump over the tip of your collarbone. You will need to have X-rays to check for a fracture.
An Xray of the left shoulder showing normal anatomy
Complications
Most people fully recover from a separated shoulder with conservative treatment. Continued shoulder pain is possible, however, if:
- You have a severe separation that involves significant displacement of the collarbone
- You develop arthritis in your shoulder
- Other structures around your shoulder, such as the rotator cuff, are damaged
Treatment
A separated shoulder is usually treated conservatively. Your doctor may recommend:
- Rest. Avoid activities that aggravate your shoulder pain, especially crossing the affected arm in front of your body. You might want to temporarily immobilise your arm in a sling to take pressure off your shoulder and promote healing.
- Ice. Ice can reduce shoulder pain and swelling. Use a cold pack, a bag of frozen vegetables or a towel filled with ice cubes for 15 to 20 minutes at a time. Do this every couple of hours the first day or two, and then as often as needed.
- Medication. Over-the-counter pain relievers also can ease shoulder pain.
- Shoulder exercises. Physiotherapy can help you restore strength and motion in your shoulder.
Most people enjoy a full recovery after conservative treatment — although the more severe the dislocation, the longer it’ll take to regain comfortable use of your shoulder. A minor separation may heal within a few weeks. A more severe separation may take several weeks to months to heal. You may always have a noticeable bump on the affected shoulder, but it shouldn’t affect your ability to use your shoulder.
If pain persists or if you have a severe separation, surgery might be an option. Surgery usually involves measures to stabilise the acromioclavicular joint and re-establish normal bony relationships in the shoulder.
Looking After Yourself
- Avoid activities that aggravate your shoulder pain — especially contact sports — until your pain disappears. Gentle exercises can help keep your shoulder muscles limber, however.
- Use ice and over-the-counter pain relievers.
- Consider investing in special protection pads designed for athletes who’ve injured their acromioclavicular joint, if you decide to return to contact sports after your shoulder has healed.
Seeking Advice
Preparing for your appointment
You’re likely to start by first seeing your family doctor (GP). However, if your separated shoulder is severe, you may be referred to a doctor who specialises in bones and joints.
Because appointments can be brief, it’s a good idea to come prepared for your appointment. Write down any symptoms you’re experiencing and any questions you want to ask your doctor.
Your doctor will have questions for you, too. Being ready to answer them may reserve time to go over any points you want to spend more time on. Your doctor may ask:
- How severe is your shoulder pain?
- When did your shoulder pain begin?
- Do you know what triggered your symptoms? For instance, have you experienced a fall or participated in contact sports recently?
- What, if anything, seems to improve your pain?
- What, if anything, appears to worsen your pain?
Your Family Doctor (GP)
Your Family Doctor will be able to diagnose and help treat your problem. He or she will be able to
- tell you about your problem
- advise you of the best treatment methods
- prescribe you medications
- and if necessary, refer you to Specialists (Consultants) for further treatment
Prevention
Regular exercise, including strength training, can help you strengthen and protect your shoulders. Start slowly, and increase your intensity gradually. This is best done under the supervision of a trainer or physical therapist.
Use proper form and protective gear for your given sport.