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Acromioclavicular Joint (AC) Injury

Introduction

AC Joint injury refers to sprain or complete dislocation at the AcromioClavicular Joint (AC Joint). This joint is formed by the outer end of the collar bone (Clavicle) and the Acromion bone which is the outer prominence of the shoulder blade.

The Joint is stabilized by the AC ligaments either side of the joint and the Coracoclavicular (CC) ligaments which prevent upward displacement of the clavicle.

AC Joint injury is a relatively common condition especially in young active people who play sport. It comprises 9% of all shoulder injuries.

The type of injury sustained has been classified according to 1-6 grading system.

In Types 1 and 2, there is partial separation between the acromion and clavicle.

In Types 3-6, complete separation at the AC joint exists as BOTH the AC ligaments and CC ligaments are torn.

Causes

This injury occurs as a result of a direct blow to the point of the shoulder.

For example:

  • Contact sports.
  • Falling off a bicycle.p>

Symptoms and signs

Diagnosis is based on patients’ symptoms, examination findings and specific tests:

  • Pain and tenderness over the point of the shoulder.
  • Bruising.
  • Swelling.
  • Prominence of the high riding clavicle (collar bone).
  • Tender to touch.
  • Increased mobility of clavicle due to joint disruption in higher grades.
  • Nerve / Blood vessel examination to exclude serious injury.

Tests

X-ray

This will show mild separation at the AC joint in Grades 1 and 2 and complete dislocation with displacement of the clavicle in other grades.

Comparison X-rays

X-rays of the normal shoulder may be taken to assess for the normal relationship of acromion to clavicle.

MRI

This may be performed if there is suspicion of injury to other structures around the shoulder.

Non-surgical treatment

Types 1-2 and Most Type 3 AC joint injuries don't need surgery and can be managed 2-4 weeks in a sling<.

Sling

A shoulder immobilizer sling is used to keep the AC Joint and rest of shoulder still to allow the ligaments to heal and settle the pain down.

Pain Killers / Anti Inflammatory Medications

Ice will help with pain and swelling in first 2-3 days.

Recovery and Return to Sport

  • Start shoulder movement and strengthening as per pain tolerance (2-4 weeks).
  • Return to sports in approx. 6 weeks.
  • The shoulder may continue to be painful for 3-6 months.

Surgery

AC Joint Stabilisation