Shoulder Impingement

What is it?

This is a collective term used to describe pain upon lifting the arm out to the side. Therefore, it's a symptom of several conditions which relate to the rotator cuff tendon and fluid filled 'bursa' surrounding the joint which can get trapped or 'impinged' between the head of the shoulder joint and its roof (acromion). Lifting the arm reduces this space causing structures within to pinch. Consequences of this include inflammation, wear and tear of the tendon.

Why does it occur?

There are multiple pathologies that can result in these symptoms, therefore it's important your clinician diagnoses the root cause prior to initiating treatment. Tendonitis - Overhead, repetitive activity of the shoulder joint such as swimming or painting can lead to inflammation and swelling of the tendon. This leaves a smaller space for the tendon to pass between the acromion and humeral head. Further damage ensures and a cyclical process occurs.

Calcific tendonitis - Calcium deposition within the tendon causes local irritation and mechanical impingement upon lifting the arm.

Bony spur - These may be present on the acromion of some patients causing tendon irritation and space reduction. A similar result is seen in acromioclavicular joint arthritis, where degenerative change leads to the development of 'osteophytes'. This new disorganised bone forms around the joint and acts in a similar way to a bony spur.

Rotator cuff tear - a partial or full tendon tear may leave the free ends to be rub within the joint. Alternatively, a full tear won't lift the arm effectively so the humeral head hits into the acromion inappropriately.

Instability - muscle imbalance can result in poor centralisation of the humeral head in the glenoid cup. Lifting the arm can cause the larger muscles (deltoid) lifting the head inappropriately towards the acromion.  Alternatively, people with bone and joint abnormalities can be predisposed to this malalignment or imbalance.

What are the symptoms?

Pain with overhead use of the shoulder is the most common presenting complaint but can also be experienced when lying on the affected side. Restricted movement leads to difficulty performing normal daily activities. You may feel weakening of the shoulder muscles secondary to this or have suffered a tear of the tendon.

How is it diagnosed?

A detailed history and examination is essential to determine the mechanism of injury and therefore appropriate treatment modality. X-rays, MRI and shoulder arthroscopy can all be used to confirm diagnosis.

How is it treated?

Non-surgical treatment usually resolves most cases within a few weeks. This involves pain relief, in the form of anti-inflammatory medications, physiotherapy and in some cases steroid injections are considered. 

Surgical treatment would begin with a diagnostic shoulder arthroscopy and proceed to removal of bursa and underside of the acromion to increase space in the shoulder joint and remove painful tissue.  An anaesthetic block is used to numb the arm which can last for several hours after the procedure. You can usually return home the same day after seeing the ward physiotherapist who will provide you with exercises to do at home.