Shoulder Pains – AC Joint Injury

The shoulder is a complex body part, with many joints, ligaments, muscles, and other tissues that work together to give us strength and mobility. When you injure any of these parts, it can cause dysfunction to the whole shoulder system. In this article, we will discuss one of the most common injuries in the shoulder, an AC joint injury.

What is the AC joint?

The Acromioclavicular (AC) joint is the joint between your clavicle (collarbone) and your acromion, which is a bone that juts forward from your scapula (shoulder blade). This joint lies just above your shoulder joint and is important for proper shoulder and shoulder blade movement. Ligaments surround the joint and keep these two bones together. There are also ligaments that extend to the coracoid process, which is another bone that juts forward from the scapula.

What is an AC joint injury?

Trauma to the shoulder can cause damage to the AC joint in various ways. This includes a direct impact to the shoulder, like falling on the shoulder or getting hit in a contact sport, but also includes indirect impacts like falling on your outstretched arm.

When the AC joint is damaged, there can be partial or complete tears to any of the ligaments that support the joint between the clavicle, the acromion, and the coracoid process. The more ligaments involved, the more severe the injury. An AC joint separation occurs when the damage to the ligaments allows the two bones to separate.

What are the symptoms?

An AC joint injury can cause pain to radiate up to the neck and down to the shoulder and upper arm. There might also be swelling and tenderness to the AC joint itself, just above the shoulder joint. In some cases the joint may separate with the clavicle resting above the acromion.

What else could this be?

An impact to the shoulder can cause many kinds of injuries that have overlapping symptom presentations. Here are some examples of injuries that present similarly to an AC joint injury:

  • AC joint arthritis
  • Fracture
  • Shoulder dislocation or subluxation
  • Frozen shoulder
  • Rotator cuff injury
  • Labral tear

Physiotherapy treatment for AC joint injury

The treatment for an AC joint injury can depend on the severity of the injury itself. Here are some key pieces in a treatment plan for AC joint injury:

  • Rest: Preventing your shoulder from doing the movements that cause pain is the first step to recovery. We often use the acronym RICE, which stands for rest, ice, compression, and elevation – important in the first two or three days to improve swelling and pain.
  • Exercise: Strengthening and mobility exercises play a huge role in recovery from an AC injury.
  • Manual therapy: Mobilization of the shoulder joint and myofascial release of the muscles surrounding it can improve stiffness and pain symptoms.
  • Taping: Tape can help to give support to the AC joint while it is recovering.
  • Dry needling: Dry needling can help to restore strength and mobility to a stiff or weak muscle. This technique can help to support strengthening and mobility exercises.

Surgery may be required for more severe cases of AC joint separation in order to enhance healing.

If you’ve had an injury to your shoulder, book an appointment with us today to start your journey towards shoulder recovery!

About The Author

Jonathan Rankin obtained his MSc in Physiotherapy at McMaster University, and also completed both a BSc and an MSc in Human Kinetics from the University of Ottawa. He has a strong background in exercise, from working as a personal trainer at the University of Ottawa to conducting research on exercise during pregnancy in his master’s degree.

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