Shoulder Impingement

The aim of this information sheet is to give you some understanding of the problem you may have with your shoulder. The leaflet has been divided into sections, describing your shoulder, what we know about shoulder impingement and your treatment options.

About your shoulder
The shoulder joint is a ball and a shallow socket joint. It is formed from a ball on the top of your arm bone and a shallow socket which is part of the shoulder blade.

Above the ball and socket joint is a ligament which is attached to a bony prominence (‘acromion’) on your shoulder blade. This forms an arch. The area between the shoulder joint and the arch is known as the sub-acromial space.

To move your shoulder and control the position of the ball on the socket, you have a group of muscles and tendons known as the rotator cuff. They attach from the shoulder blade onto the top of the arm bone, passing through the sub-acromial space. One tendon (‘supraspinatus’) sits in the middle of the sub-acromial space. A small fluid lining (‘bursa’) cushions the tendon from the roof of the arch.

When you move your arm away from your side, the rotator cuff works to keep the ball centred on the socket. When your arm reaches shoulder height (horizontal), the sub-acromial space is narrowed. Above and below the horizontal, the space is larger.


What is impingement?
The rotator cuff appears to be vunerable to tendon damage or degeneration (wear and tear). This particularly affects the supraspinatus tendon in the sub-acromial space. Unfortunately this is more likely as we get older.

Damage to the tendon(s) can range from inflammation to tears. We do not know why some people are susceptible to having these problems. Sometimes there is a precipitating event that makes the shoulder painful. For example over-use, a new (overhead) arm activity such as DIY, pruning or hedge trimming in the garden, carrying luggage. This may cause irritation of the tendon which gives pain and weakness.

Once the tendon becomes affected, it swells, filling more of the space, which increases the chance of the tendon and bursa becoming pinched. This is known as ‘impingement’. Anything that narrows the space between the rotator cuff and the arch above, will tend to pinch and irritate the cuff.

For example, if your shoulder blade is dropped, the bony prominence will be angled downwards, decreasing the space. Sometimes small calcium deposits can be found in the tendon, as a result of inflammation.

Tears in the tendon can occur from sudden injuries such as falling, but more commonly they develop gradually, as a wear-and-tear effect on the tendon.

This is partly age related, but may result from longstanding impingement.

The tears can be partial or full thickness.

How common is it?
Extremely! It is the most common problem of the shoulder. 20% of people will have symptoms at some time in their lives. It most frequently begins in middle age (between the ages of 45–65).

What are the symptoms?
The main complaint is one of pain, often felt on the outside of the upper arm. A classic resentation is of a painful arc on movement when the arm is lifted out to the side and up to your ear. This corresponds with the narrowing of the sub-acromial space

Pain is also commonly felt on twisting movements such as putting jackets and coats on. When the inflammation is active, you may experience pain at night and when your arm is resting. Sometimes people describe a ‘locking’ sensation in the arm on certain movements.

Symptoms of neck, shoulder, upper arm or hand pain should be reported to the doctor. In addition tell them if you feel pins and needles or tingling in the arm or hand as these may indicate that the pain is coming from your neck, via the nerves in your arm.

Why does it occur?
The exact cause of sub-acromial impingement is not known. It appears that some people may be susceptible to a wear-and-tear process in the tendon.  The problem appears to be within the tendon and it starts to fray and split.  Mechanical triggers (i.e. changes in posture or activity) where the tendon is stressed, may then cause episodes of pain.

What tests may be done?
The main way we diagnose shoulder impingement is from your symptoms and by examining your shoulder. Sometimes an X-ray will be taken, although this only shows bones and does not show muscle inflammation or wear and tear.  If there is some suspicion that the tendon is torn, you will be sent for an ultrasound scan or an MRI (Magnetic Resonance Image). Both of these scans show the tendons, and can highlight if they are torn. The ultrasound scan is commonly done in this hospital and often when you attend clinic.

What are your treatment options?
Treatment is usually non-surgical to begin with. An operation is usually only done when your shoulder has not responded to the following ‘conservative’ (non-surgical) treatments.

Non-surgical treatments (‘conservative care’).

1) Injections

These are given into the sub-acromial space aiming for the bursa not the tendon itself. Usually a mixture of local anaesthetic and steroid is given, from the back of the joint. Although you may feel increased pain for the first 24 hours, injections can have a good effect. Doctors will generally not want to give more than three injections into one shoulder in a year. If your symptoms keep returning, other treatment methods would be suggested.

2) Physiotherapy

An assessment of your shoulder will be done, and from this, an individual programme of exercises given. These may include exercises to strengthen the muscles around your shoulder blade, improve your posture, stretching exercises and/or strengthening the rotator cuff. Although the exercises may be hard work, tight or uncomfortable, they should not be painful. If you are unable to do any form of exercise because of pain, the physiotherapist may offer treatments such as ultrasound and laser. It is difficult to prove that these work, but they rarely cause worsening symptoms.

Thorough assessment of your arm, advice and exercises are probably more important aspects of treatment. The advice may include discussing the selfhelp ideas listed in the next section of this leaflet.

The majority of people find their symptoms settle without the need for an operation

3) What you can try – ‘self-help’ ideas – modify your activities.

The aims of the treatment are 

  • to reduce the stress on the tendon(s) so that your body can try and heal the area.
  • to break the pain cycle. Change things!


How to reduce the stress on the tendon

  • If possible, stop the activity that causes pain or find a different way of doing it.
  • For example, you may find that you tend to use your arm at shoulder height. Try to avoid this by raising yourself up (i.e. using steps for sustained overhead activities).
  • Another common movement that aggravates shoulder impingement is raising your arm with the elbow twisted outwards. Try keeping the elbow in and then raise your arm, palms up to the ceiling, so you are trying to clap your hands up overhead, similar to a waiter balancing a tray on their palm. Is this less painful? It may feel extremely awkward to begin with – however, with practice, it will feel more familiar.
  • Remember your shoulder blade is half of your shoulder joint. Look in the mirror, is your shoulder blade lower on the side that hurts? Try some shoulder blade exercises (see diagrams at the back of this leaflet). Think about your posture – try and gently ‘square’ your shoulder blades, keeping your elbows and body still.
  • In addition, try sitting with your arm by your side, with the elbow propped on an arm rest. This will tend to keep the shoulder blade up.
  • If you are involved in a sport/profession using repetitive movements, seek expert advice on your technique. A physiotherapist may be able to give you advice on your movement patterns as well as appropriate stretching and progressive strengthening exercises.


How to influence/break the pain cycle

All the ideas mentioned above can reduce the pain. Specific treatments may also help.

  • Pain medication (i.e. tablets).
  • Try using anti-inflammatory cream or gel on the area (from chemist without a prescription, but check you have no allergies or conditions that are influenced by these drugs).
  • Try using a wet ice-cube and massage it over the tender area for 10 minutes. If you have not already tried some of ideas listed above, it is worth doing so now.


Surgical treatment

If your symptoms do not settle with the above measures, an operation may be suggested. The operation done most frequently is a ‘sub-acromial decompression’ (SAD). This is done by keyhole surgery (arthroscopy) and you are in hospital for a day. The operation involves cutting the ligament and shaving away part of the prominence on the underneath of the acromion bone. This aims to increase the size of the sub-acromial space.

If the rotator cuff muscle is torn, the surgeon may be able to repair it.

Rehabilitation after the repair operation is longer than after the decompression operation alone.


Patient Information Leaflets Nuffield Orthopaedic Centre NHS Trust