Rotator Cuff Impingement
The rotator cuff is a group of muscles (supraspinatus, infraspinatus, teres minor and subscapularis) that are attached to the top of the arm bone (humerus). The rotator cuff contributes to the stability of the shoulder and controls smooth motion of the shoulder.
The rotator cuff runs in a narrow space (subacromial space) under the acromion process which is a part of the shoulder blade. To reduce friction under the acromion the rotator cuff is covered with a fluid filled sac called the subacromial bursa.
Subacromial impingement is a common cause of shoulder pain which occurs due to catching of the rotator cuff under the acromion.
Causes of Subacromial Impingement
Subacromial impingement is usually caused by a combination of a number of factors:
- Weakness and thickening of the rotator cuff tendon (Rotator cuff tendinopathy)
- Inflammation of the subacromial bursa (subacromial bursitis)
- Curved or hooked acromion (subacromial spur)
Most patients present with pain around the shoulder which is felt usually over the outer aspect of the upper arm. Pain is usually precipitated on attempting activities above shoulder level. Occasionally the pain is worse at night and can disturb sleep.
A diagnosis is usually made by history taking and clinical examination. Investigations like a plain x-ray and an ultrasound or an MRI scan may be needed.
- Steroid Injection & Physiotherapy In most patients the symptoms of subacromial impingement can be improved with an injection of steroid and local anaesthetic into the subacromial space. This helps improve the pain and allows physiotherapy exercises to strengthen the rotator cuff.
In most patients 1 or 2 steroid injections are sufficient to improve the symptoms. However multiple injections carry a risk of weakening the rotator cuff tendon and may lead to a rotator cuff tear.
- Arthroscopic Subacromial Decompression If non-operative treatment in the form of a subacromial steroid injection and physiotherapy fail to improve the symptoms then surgery may be needed. This is performed as an arthroscopic (keyhole) procedure which involves clearing of the inflamed bursa overlying the rotator cuff and shaving of any subacromial bony spurs that might be impinging on the rotator cuff tendon.
The procedure is done under a general anaesthetic and involves 2 or 3 small puncture wounds around the shoulder.
Following the surgery the arm is supported in a sling for comfort for 24 hours. You would be prescribed oral painkillers and most people are able to go home the same day a few hours after surgery.
Following the surgery you need physiotherapy for a few weeks which will focus on achieving range of motion and strengthening the rotator cuff.
Risks And Complications
- Infection The risk of infection following arthroscopic surgery is less than 1%.
- Stiffness A very small proportion of patients may develop stiffness following an arthroscopic subacromial decompression. This usually improves with intensive physiotherapy but may occasionally need a steroid injection into the shoulder joint or occasionally need surgical intervention in the form of another arthroscopic (keyhole) procedure.