Dislocation of the joint between the clavicle and the scapula (acromioclavicular joint)


What is it about ?

The joint between the scapula (scapula) and the clavicle (acromioclavicular joint) can, like other joints, become dislocated. This is called a dislocation.

The scapula has a protrusion called the acromion that overhangs the shoulder. The collarbone extends from the shoulder to the breastbone and serves as additional support for the shoulder. To provide this support, several ligaments strengthen the connection between the clavicle and the scapula (scapula).

The acromioclavicular joint is a small joint and it can dislocate if ligaments are involved. There are several degrees of dislocation.

How does it happen?

Usually, the dislocation is caused by a fall on the shoulder or while playing contact sports.

How to recognize it?

There may be pain and swelling in the upper part of the shoulder after a fall on it.

How is the diagnosis made?

The doctor always begins by palpating the sensitive area. If the acromioclavicular joint is dislocated, he may feel a lump. Depending on the severity, the doctor may eventually move this lump in an up and down motion.

The suspicion is confirmed by an X-ray of the injured shoulder, always compared to the other shoulder. On the image, the doctor can also determine the severity of the dislocation.

  • Grade 1: The joint is sensitive to movement and pushing, but the image is normal. The joint may have been dislocated for a while, but has snap back into place.
  • Grade 2: The collarbone is moved slightly upward (by a distance less than its own diameter), and the joint is slightly open.
  • Grade 3 – 6: The surrounding structures of the acromioclavicular joint are injured, making the joint unstable. The clavicle is movable from top to bottom in a “piano key”: the end of the clavicle makes a bump and can be moved up and down. The clavicle has been displaced a distance greater than its own diameter, and the space between the bony structures has greatly increased.

Ligament damage is not seen on an x-ray. They could possibly be seen on an ultrasound or a CT scan.

What can you do ?

How quickly you can use the arm again depends on the severity of the injury. Follow the doctor’s advice.

What can the doctor do?

It is important for the doctor to properly assess the grade of the dislocation, as treatment is determined based on the severity.

  • Grade 1: You can move your arm immediately within the limits of the pain. You can gradually increase the load in the weeks following the accident.
  • Grade 2: Keep your arm in a support bandage (sling) for 1 to 3 weeks. Then your arm is moved in the same way as in a grade 1 dislocation.
  • Grade 3: we can still often be content to wait. This grade is sometimes difficult to distinguish from a grade 4 to 6.
  • Grade 4 to 6: an operation is sometimes necessary to ensure good healing. For this, a screw is placed between the shoulder and the collarbone.

Want to know more?

Source

Foreign clinical practice guide ‘Dislocation of the acromioclavicular joint’ (2000), updated on 22.06.2017 and adapted to the Belgian context on 17.01.2020 – ebpracticenet