AC Joint Pain

Home » ShoulderAugust 1, 2019

Background

The AC joint, otherwise called the acromioclavicular joint, is the joint that connects your clavicle to the acromion of the scapula. This joint sees significant stress through axial loading on two small weight bearing surfaces. These high stresses cause pain and degeneration over time.

AC Joint Injuries

Most injuries that take place on this joint do not need surgical intervention. Often, adequate rest, and even immobilization in some cases, relieves the pain. Injuries to the AC joint can be chronic or an acute injury. Chronic – Persistent axial loading through the AC joint causes increased stress on the joint. In younger patients activities such as bench press, push-ups, and repetitive overhead movements can aggravate pain here. Acute – Acute trauma to the shoulder can cause injuries such as AC joint separations. AC separations are graded according to the ligaments torn and amount of displacement. See below for grading:

  • Type 1 separation: known for having the ligament either partially torn or stretched beyond its normal limits.
  • Type 2 separation: known for tearing the ligament completely and displacement is seen, there is a bump where the AC joint is from the bone rising up a little.
  • Type 3 separation: known for causing complete tears of the AC ligament as well as the coracoclavicular ligament. This causes extreme displacement of the clavicle that is also known for being called a piano key because you can push the clavicle down and it will bounce back up once released.
  • Type IV separation: CC and AC ligaments are torn with tenting of the skin. This is a non-reducible injury that requires surgery.
  • Type V separation: CC and AC ligaments are torn with shoulder droop. Increased CC distance with >100% displacement compared to contralateral side. This is non-reducible and requires surgery.
  • Type VI separation: CC and AC ligaments are torn with inferior displacement of the distal clavicle. This is a rare injury and requires surgery.

Treatment

In the case of AC joint arthritis, treatment options include rest, NSAIDs, physical therapy to improve scapular mechanics, and steroid injections.

For AC separations, often times non-operative management is appropriate with immobilization in a sling. Non-operative management is usually indicated for Type I and II injuries and even Type III injuries in certain circumstances. Type IV through VI injuries require surgery for best outcomes.

See the following link for one approach to repairing the AC joint. Sometimes, additional grafting is used to augment the repair. https://www.orthoillustrated.com/shoulder/instability/animation/25-ac-joint-repair-with-arthrex-dog-bone-button

Rehabilitation

If surgery is indicated, your surgeon will develop a rehabilitation plan specifically for you. This rehab often includes the following: Sling from 0-6 wks and start gentle physical therapy to work on motion without disrupting the repair. From 6 – 12 weeks, the brace is generally discontinued and motion is progressed. No strengthening or lifting should be done as the graft.repair is still maturing. From 12 – 24 weeks, isometric exercises begin.