Impingement syndrome (trapped shoulder tendon)
Shoulder impingement syndrome is pain and often weakness when you raise your arm, caused by a muscle tendon "catching" in your shoulder.
It involves the rotator cuff tendon – a tough, rubbery cord that connects the muscles in your shoulder to the top of your arm. The tendon and muscle run through a narrow space at the top of the shoulder called the subacromial space.
In shoulder impingement syndrome, the tendon becomes trapped in this space and repeatedly scrapes against the bone above, causing pain that tends to be worse when you raise your arm over your head.
You may also experience a persistent ache in your shoulder and pain at night.
Shoulder impingement syndrome can start suddenly after an injury, or (generally from middle age onwards) it can come on gradually without any obvious cause.
What causes shoulder impingement syndrome?
The subacromial space is naturally quite narrow, especially when the arm is raised. Anything that further narrows this space can cause the tendon to become trapped.
Possible causes include:
bone spurs under the bony roof (acromion) at the top of the subacromial space can narrow the space and catch on the tendon
swelling or thickening of the rotator cuff tendon – which may result from an injury or general overuse of the shoulder
inflammation of the fluid-filled sac (bursa) that lies between the rotator cuff tendon and acromion (known as "bursitis")
a build-up of calcium deposits within the rotator cuff tendon
Seeking medical advice
See your GP if you have persistent shoulder pain.
They should be able to diagnose shoulder impingement syndrome by asking about your symptoms and examining your shoulder. You may also be asked to do some specific arm movements to help them work out the cause of your pain.
If the cause of your pain is unclear, your GP may refer you for a specialist assessment by a shoulder surgeon, who may also carry out some scans of your shoulder. This can help to rule out other possiblecauses of shoulder pain.
Treating shoulder impingement syndrome
Caring for your shoulder at home
If shoulder impingement syndrome is only mild, the following measures may be all that are needed:
Rest the tendon –Avoiding any overarm movements will help prevent any further inflammation (swelling) or damage. Your doctor or physiotherapist will tell you how long you should rest it for, and when you should start exercises (see below).
Ice packs – Holding an ice pack to the shoulder for around 20 minutes several times a day may help to ease the pain. Don't put ice directly on your skin – wrap it in a towel. If you don't have an ice pack, try ice cubes or a bag of frozen vegetables wrapped in a towel.
Painkillers –Mild non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, can provide short-term pain relief and are available as tablets or a gel that you apply to the shoulder. Other painkillers, such as paracetamol, may also help to ease the pain. If your pain is more severe, a stronger painkiller such as codeine can be prescribed.
While it's important to rest the shoulder joint, you shouldn't stop movement altogether. Inactivity will cause the muscles to weaken, which will worsen the problem and cause your shoulder to stiffen up. For this reason, a sling is not usually recommended.
Your GP may refer you to a physiotherapist, who will be able to recommend some arm exercises to help stretch and strengthen your shoulder, and improve your range of movement.
After an initial period of supervision by a physiotherapist, you will usually be able to continue doing these exercises at home.
Corticosteroids are medications that can be used to reduce inflammation and relieve pain. If there is swelling and evidence of inflammation in your shoulder, corticosteroids can be injected directly into the affected area.
They may also be combined with local anaesthetic to further help relieve your pain.
Although corticosteroid injections can relieve pain, without physiotherapy they do not have a long-term effect, and it's common for the pain to return. You can sometimes have another injection, but you will need to wait at least six weeks. Usually, no more than one to two injections into the same area are recommended.
Possible side effects of corticosteroid injections include thinning and lightening of the skin.
If the treatments above aren't effective, you may need an operation to widen the subacromial space in your shoulder, so the rotator cuff tendon is no longer rubbing against the bone above. This is known as subacromial decompression.
This can usually be done using a technique called arthroscopy, which is a type of keyhole surgery carried out under general anaesthetic, where special surgical instruments and a thin, flexible tube containing a camera are inserted through small cuts in your skin.
This means you should recover faster and with less scarring than if a larger cut was made. Most people are able to go home the same day or the day after.
This technique can also be used to remove any calcium deposits that have formed in the tendon in your shoulder.