AC Joint Problems

The acromioclavicular joint is often referred to as the AC Joint. This joint can be found at the top of the shoulder, on the outer end of the collar bone (clavicle). Like any joint, it can develop pain from arthritis. The pain is usually at the top of the shoulder, particularly when reaching high or sleeping on the affected side. It can make it difficult to perform usual daily activities such as washing your hair and reaching into high shelves. It can also affect your ability to work if you have a manual job.

Who gets AC joint arthritis?

Since AC joint arthritis is due to wear cartilage at the outer end of the collar bone, it tends to come on as people age and is uncommon in under-40s. It tends to affect men more than women and is especially pronounced in people who have manual jobs or who do a lot of weight training. It usually comes on by itself, but some people recall an injury that sets it off.

Weightlifters sometimes develop a related condition, called osteolysis of the distal clavicle. It is also referred to as weightlifter’s shoulder. This causes very similar symptoms but is seen more frequently in younger people. It often settles with rest and a change in your exercise programme.

What causes AC joint arthritis?

For many people, no particular cause can be found. Some people with manual jobs or who do a lot of weight training appear to be more prone to developing this problem. You are also more likely to develop this condition if you injure the AC joint and suffer a sprain or partial dislocation.

Symptoms

01 Pain usually at the top of the shoulder, particularly when reaching high or sleeping on the affected side

02 Difficulty performing usual daily activities such as washing your hair and reaching into high shelves

03 Difficulty with ability to work if you have a manual job

How is AC joint arthritis diagnosed?

This starts with a conversation with your doctor to describe when you experience the pain. You will then be examined, with some specialised tests that help to check where the pain is coming from. You will also have an X-ray focused on the ACJ joint. If you have arthritis, the joint often looks narrowed, with extra outgrowths of bone called osteophytes which can press on the tendons below and cause pain.

Treatment options

Non surgical

Simple painkillers and change of lifestyle

For some people, just knowing what the problem is, and having the reassurance that there is no major damage to the shoulder is enough. The pain can be controlled with simple painkillers, such as paracetamol and anti-inflammatories (if you can take them). This may be coupled with simple changes to your lifestyle, such as sleeping on the opposite side, changing your level of physical activity and avoiding working overhead for prolonged period. For some people, the pain simply burns itself out over a number of years.

Non surgical

Physiotherapy

A course of physiotherapy may be effective for controlling the pain by changing how you move your shoulder to relieve pressure on the painful AC joint. Your physiotherapist will assess your movements and teach you ways of moving your shoulder without experiencing the pain. If you have an imbalance in the muscle strength around your shoulder, this will also be addressed. It can take several months to get the full benefit of physiotherapy, so it is important to work hard early on, even if you do not feel an immediate benefit.

Non surgical

Steroid injection

You may be offered a steroid injection into your AC joint. This is sometimes referred to as a cortisone injection. The purpose of this injection is to settle down any inflammation in the joint. By taking the pain away, even temporarily, it can make it easier to do the exercises given to you by your physiotherapist. These injections can work for several months and be repeated 2-3 times per year if you find them helpful. There are several rare risks of steroid injections:

Allergic reaction: This is very rare, but can be life-threatening.
Infection: This is rare, but can result in severe pain 1-2 weeks after the injection and may require surgery to wash out the injection.
Change in the colour or texture of your skin where it is injected. This is very uncommon and more pronounced in people with darker skin colours.
Steroid 'flare': This can result in a temporary worsening of pain from 1-3 days after the injection.

Surgical

Surgery

If the above treatments are not successful, surgery may be helpful to treat AC joint arthritis. This is usually performed 'keyhole' and is often referred to as an arthroscopic AC joint excision.