Shoulder impingement syndrome is the name given to a shoulder pain problem caused by the repetitive compression of part of the rotator cuff under the bony arch of part of the shoulder blade.
The rotator cuff muscles come from the scapula (shoulder blade) and head for the side of the ball of the arm bone where they insert. As they get towards the ball they make up a broad, strong tendinous sheath called the rotator cuff.
Just above the head of the humerus is a bony part of the scapula called the acromion and when the arm is raised at the shoulder the ball of the arm bone can impinge on the underneath of the acromion.
Who Gets Shoulder Impingement?
Shoulder impingement can occur to anyone, but athletes who throw or perform overhead actions such as in racquet sports are most vulnerable. Typical risky sports include tennis, squash, baseball and swimming.
How Is Shoulder Impingement Classified?
An eminent shoulder surgeon called Neer classified impingement into three categories in 1972.
- Stage 1. Mostly in young people under 25. There is acute inflammation, swelling and bleeding in the rotator cuff. Pain occurs during exercise but the strength and movement of the shoulder is normal. This can be managed with physiotherapy and settles back down to normal.
- Stage 2. Mostly in people between 25 and 40 years old. The rotator cuff tendon develops tendonitis and becomes fibrosed. There may be some loss of shoulder movement and pain at night. This is not usually treatable without operation.
- Stage 3. Mostly in people over 40 years of age. The rotator cuff tendon develops tears and bony outgrowths occur under the acromion. Mobility and strength of the shoulder is lost. Removal of the bony outgrowths and repair of the rotator cuff is often necessary.
Shoulder Impingement Symptoms
- Pain over the front, top and side of the shoulder
- Worse with overhead activities or when sleeping
- Pain worse with aggravating activities and better with rest
- A painful arc, where there is pain between approximately 60 and 120 degrees when the arm is lifted up to the side and slightly forwards.
Shoulder Impingement Treatment
Physiotherapy management of shoulder impingement has been shown to be effective, decreasing shoulder pain and increasing shoulder function. If neck pain and upper back pain are also present, a physio can assess these areas to exclude them as causes of the pain or to treat them if they are involved.
Physiotherapy techniques for treating shoulder impingement include mobilisation techniques, shoulder exercises, acupuncture, ultrasound and laser therapy.
A physiotherapist will strengthen the rotator cuff muscles and the middle and lower trapezius muscles to stabilise the scapula as a base of stability for the movements of the shoulder joint.
Injections into the space under the acromion where the impingement and inflammation occurs can give good results. Local anaesthetic and corticosteroid drugs are the typical agents used in this treatment. Some physiotherapists are qualified to prescribe and give this kind of injections.
Surgery for Shoulder Impingement
If the problem continues for over six months or more, then surgery might be considered. Subacromial decompression is the main operation, where part of the acromion may be removed and any bony outgrowths trimmed. However, the evidence for surgery being better than conservative management is variable.
Arthroscopic subacromial decompression may give better results and may improve function in up to 90% of patients.
Physiotherapy after the operation will concentrate on restoring range of movement and strengthening the rotator cuff muscles round the shoulder required for normal arm function.