AC JOINT OSTEOARTHRITIS (SHOULDER OSTEOARTHRITIS)

AC Joint OA

Your acromioclavicular (AC) joint in your shoulder is quite a common area for osteoarthritis (OA) to form as we reach our 40s & 50s. Wear and tear of the protective cartilage that provides cushioning of your AC joint leads to arthritic changes in your AC joint. This can be very painful and lead to problems using your shoulder for everyday activities and movements.

AC joint

Your shoulder complex consists of three separate bones: your scapula (shoulder blade), your humerus (upper arm bone), and your clavicle (collarbone).

Your AC joint consists of two bones that connect via articular cartilage at the ends of the bones. The function of your articular cartilage is to act as a shock absorber. It creates a smooth surface, allowing your bones to glide over each other as you move.

There are differences in how your AC joint operates in comparison to other joints such as your knee or ankle. Your AC joint only needs to move a very small amount, just enough for your shoulder to move freely.

What causes degeneration of your AC joint?

Because our entire shoulder complex can move very freely, and we use it frequently throughout the day, it is subject to more wear and tear than other joints. For example, your AC joint is subject to greater load when you raise your arm in overhead activities. This might be due to daily activities at home or at work. It is also quite common in weightlifters and people who repeatedly lift heavy loads or weight above their head.

One of the major causes of AC joint osteoarthritis is due to poor posture. If your postural muscles don’t have the capacity to keep your body in good biomechanical alignment, your AC joint can’t function efficiently. For example, if your body is hunched over a desk, your posture would consist of a rounded upper back, a forward poking head, and rounded shoulders. This is not an ideal resting or starting position for movement of your shoulder complex, including your AC joint. 

Initiating repetitive movements in daily or sporting activities from poor anatomical alignment, will eventually lead to an increased strain on your ligaments and joints. This can cause the development of AC joint osteoarthritis.

Another cause of AC joint osteoarthritis is if you have sustained an injury to your AC joint, such as an AC joint separation. An AC joint separation or dislocation can occur from falling onto your shoulder. Even though your shoulder separation and your injury do heal, you may find that you are more prone to develop degeneration in your AC many years later.

What does AC Joint Osteoarthritis feel like?

If you have AC joint osteoarthritis, you will usually feel pain and tenderness at the front of your shoulder on or near your AC joint. Moving your arm across your chest, compresses your AC joint and often increases your pain. 

In some cases, you may not be able to pinpoint the exact location of your pain. It can sometimes be felt in the shoulder, the front of your chest, and also refer to your neck. If you have previously sustained an injury, you may have a larger bump over the joint on the painful shoulder. Sometimes you can hear your joint click or snap as you move your shoulder.

Physiotherapy Treatment of AC Joint Osteoarthritis

Non-Surgical Rehabilitation

After your physiotherapist performs an initial assessment and examination, a diagnosis of your shoulder symptoms will be made.  Your physiotherapist will then commence treatment for your AC joint osteoarthritis.

Treatment will initially most commonly be hands-on treatments such as deep and/or soft tissue release of surrounding muscles and fascia, and joint mobilisation to ease your pain. Often the pectoralis minor muscle has shortened due to sustained forward rolling of your shoulder and needs to be lengthened. 

Dry needling may also be used to relieve your pain and to eliminate tight muscles bands or inflammation at the site of muscle attachments. As your pain settles, range-of-motion home exercises, and postural and shoulder strengthening exercises will also be prescribed at graduated levels.

At first, exercises are performed with your arm kept below your shoulder level. As you improve, we progress your rehab exercises to include strength exercises for your rotator cuff and shoulder blade (scapula) muscles. Our goal is to get your shoulder moving with the correct biomechanics and to minimise your symptoms.

Of course, your physiotherapist will also need to look at what things you are doing and if they are contributing to your symptoms. For example, we can assess things like;

• the set-up of your work station
• observing how you lift or perform certain exercises in the gym
• mimicking a movement you perform repetitively at work or home

We will provide you with feedback, education and strategies to invoke change to your movement dysfunction such that further aggravation down the track is minimised or avoided altogether.

BACK TO BLOG