(Also known as painful arc syndrome and subacromial bursitis)
Shoulder impingement is a syndrome of pain felt around the shoulder when the arm is raised to shoulder height or above. This means that simple activities, such as brushing your hair, reaching for items on shelves, driving or getting dressed can trigger your pain.
Because your shoulder is such a mobile joint, even small structural, control or movement problems around your shoulder can cause internal parts to rub painfully against each other.
The subacromial space is the area between the top of your shoulder (the acromion), and the rotator cuff tendons (particularly supraspinatus and infraspinatus tendons). A fluid filled sac called the ‘subacromial bursa’ occupies this space and this gets inflamed in impingement. The diagram below shows this bursa and it’s location in your shoulder
Figure 1 Front and side-on views of the subacromial bursa (blue). Your larger outer muscle, the deltoid, has been removed to show the deeper structures
Typically a gradual onset of symptoms, with pain when raising or lowering the arm, often worst in the mid region of your arc of motion. Initially the shoulder tends to be painful only during motion, but this may develop into a constant pain like ‘toothache’ in the shoulder. it can affect sleep and often patients cannot lie on the affected side. Most people locate the pain to their upper outer arm.
The way you describe your symptoms and your examination findings are suggestive. Shoulder x-rays exclude other causes of pain. Ultrasound or MRI imaging can help identify any structural injuries in the shoulder. Occasionally, targeted injections can help localise the source of your pain.
Shoulder impingement is very common. Most patients are between 40 and 65yrs old and it is slightly more common in women. Some sports are 'high risk' for impingement (e.g. swimming and tennis)
There is natural variation in the shape of our shoulder blades. Some people have a tighter subacromial space in their shoulder and are therefore more prone to impingement. As we age, we can develop extra ridges of bone in our shoulder. These ‘bone spurs’ can cause impingement. These spurs are resected during a subacromial decompression.
With modern lifestyles, ageing and injury, many of us adopt unhelpful or abnormal postures causing our shoulder blades to sit and move incorrectly. This increases our risk of impingement. Even muscles and postures in other parts of your body can affect your shoulder joint. It is common to discover subtle weaknesses in core stability or the legs of patients with shoulder pain. We can also develop strength and control deficits in our rotator cuff muscles that can provoke symptoms of impingement.
By the time you have sought a specialist referral, you have probably tried simple measures, such as activity modification, painkillers and anti-inflammatories.
Physiotherapy. Correction of postural problems, specific muscle weaknesses and shoulder rhythm will cure impingement in many patients, although you may need a cortisone injection to help you complete your physiotherapy course. It typically takes 6-10 weeks to achieve an enduring improvement but, as with all physiotherapy, only by doing your prescribed exercises will you achieve positive results. A physiotherapist with an interest in shoulder problems will assess you carefully to identify which aspects need attention and then prescribe a few simple exercises that you should be able to do daily to help.
Subacromial Cortisone Injection. Your surgeon may recommend an injection. This is usually performed in the clinic. The injection contains local anaesthetic (to numb the pain for 6 hours after the injection) and Cortisone (a powerful anti-inflammatory medicine for prolonged relief). It is normally only moderately uncomfortable and you can drive home. The risks of injection are extremely low and most patients enjoy significant relief, providing an excellent window of opportunity for the physiotherapist to help you cure your problem.
If your symptoms remain troubling after a good quality rehabilitation programme, you and your surgeon may decide it’s time to consider surgery. This involves a subacromial decompression. More information on this procedure is available in the Treatment section.
Overall, 70% of patients get better with physiotherapy and an injection. For those that go on to have surgery, 85% to 90% will be happy with their outcome, but it can take several months (6-9 months) for full recovery. It is rare (less than 5%) for patients to be made worse with surgery
Making the right choice about the best treatment for you means getting the right information. During your consultation, please do feel free to ask Mr Granville-Chapman to explain anything that you do not fully understand, and for his advice about the pros and cons of any treatment.