Subacrominal impingement

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Subacromial impingement – also called shoulder impingement – is a painful condition that develops when the shoulder tendons or bursa (a cushion that prevents rubbing and irritation of the tissues) get pinched during movement of the shoulder.

It is a common cause of shoulder pain. It can lead to inflammation of the rotator cuff tendons (tendinitis) and bursa (bursitis). Pain can also come directly from these tendons due to inflammation or degeneration without physical catching or impingement. This is sometimes called subacromial pain syndrome.

Causes of subacromial impingement

The condition can be caused by repetitive overhead movements such as painting, swimming, tennis or lifting. Abnormalities or spurs of the bone on the shoulder blade above the tendons (the acromion) can cause the catching or pinching of the tendons. Problems or poor condition with the tendons themselves can also lead to impingement including tears in the tendons.

Symptoms of subacromial impingement

The symptoms of shoulder impingement, which can come on suddenly or gradually, include:

  • Pain in the top and outer side of your shoulder and upper arm that makes it difficult to perform certain movements, such as reaching behind your back or putting your coat on.
  • Weakness in the arm due to pain
  • Pain when you lift your arm above your head.
  • Pain or aching at night which can affect your sleep.

If these symptoms are accompanied by stiffness in the shoulder, you may have a frozen shoulder rather than just pure shoulder impingement.

Subacromial pain without physical impingement is sometimes difficult to distinguish as it causes a similar pattern of pain but may come from poor condition of the rotator cuff tendons and muscles.

Diagnosis of subacromial impingement

A physical examination will be used to assess pain and muscle function in your shoulder joint. You may be referred for an X-ray to rule out other causes of pain, such as osteoarthritis, and to identify any large spurs. You may be also be referred for an ultrasound or MRI scan to check whether you have a rotator cuff tendon tear, especially if the shoulder is weak or if you have had an injury.

Treatment of subacromial impingement

You may be offered a range of treatments depending on the severity of the condition and how long it has bothered you. If there has been an injury of if there are tears in your rotator cuff then treatment may need to be focussed on repairing the damage rather than treating the impingement directly.

Painkilling medication and anti-inflammatories can help relieve pain. You should avoid activities that aggravate the condition but it’s important to continue moving your arm to keep the muscles in good condition and prevent stiffness.

An exercise program is an important part of treatment and you may be referred to a physiotherapist to guide you through this. This is designed to strengthen the rotator cuff muscles and make sure the shoulder is well balanced. It takes time to achieve this and hard work over many months may be required to get the best results.

In some cases, you may be offered injections such as steroid into the shoulder to reduce inflammation in the bursa and tendons.

Surgery for impingement can be helpful for some people with pain that isn’t improving satisfactorily with other treatments. This is called subacromial decompression.

Subacromial decompression surgery is used to widen the space around the rotator cuff tendon so it does not rub or catch on anything nearby. It is normally performed as a minimally invasive arthroscopic procedure under general anaesthetic.


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