Shoulder impingement is a frequently used term describing pain in the shoulder due to the ‘pinching’ or impingement of soft tissues (tendons and bursa). The shoulder is made up of three bones: your upper arm bone (humerus), shoulder blade (scapula) and collar bone (clavicle). The rotator cuff, made up of four muscles, hold the humerus in the socket and allow movement of the shoulder. The bursa is a small fluid sac, which sits between the bone of the upper shoulder (acromion) and the rotator cuff to allow smooth gliding of the tendons as the shoulder moves. Impingement of these structures can occur when the arm is raised to shoulder height and the space between the acromion and rotator cuff narrows.
Causes of Injury
In a healthy shoulder, there is enough space for rotator cuff tendons to slide through without contracting the acromion when the arm is raised overhead. If there is a relative reduction in the joint space due to repetitive use of the shoulder in an overhead position, arthritis or bone spurs or loss of control of the shoulder movement, impingement of the structures that pass through this space can occur. If this impingement process continues, inflammation of the bursa and tendons may occur, causing pain. Weakening of the tendons can then occur, increasing a person’s risk of a rotator cuff tear. There are a number of factors that can increase a person’s risk of developing Shoulder Impingement Syndrome, including:
- Age (most common in people over 30 or younger athletes)
- Repetitive overhead activity- swimming, throwing, weight lifting, racquet sports.
- Occupations that require heavy or repetitive work such as with hammering, warehouse workers and painters.
- Sleeping with the arm under the pillow
- Past history of shoulder injury
- A more hooked or curved acromion shape
- Shoulder instability or reduced control of the shoulder, causing the arm bone (humerus) to move upwards into the acromion, impinging the soft tissues
Signs and Symptoms
- Shoulder pain when the arm is raised overhead, particularly out to the side/ ‘painful arc’
- Pain generally worsens over time
- Possible referral/spreading of pain down the arm
- Pain may be relieved by rest initially
- A “catching” sensation may be felt when the arm is lowered
- Muscle weakness
- Pain when sleeping on the affected side
Most individuals respond well to physiotherapy treatment. The aim of treatment is to reduce associated pain and inflammation. Treatment and management options include:
- Advice regarding activity modification/relative rest
- Physiotherapy- massage, ultrasound, joint mobilisation and stretches
- A comprehensive exercise program including range of movement exercises, strengthening, stretching, activity specific tasks and exercises to improve control of the shoulder.
- Pain relief and anti-inflammatory medications may be recommended.
If symptoms persist, an injection of corticosteroid and/or anaesthetic medication into the joint may be recommended to assist in reducing pain and inflammation. Surgery may be required if the shoulder still fails to improve. In this case, the surgery may remove any bone spurs or the bursa, shave off or remove part of an enlarged acromion and repair any damage to the rotator cuff.
Return to Activity
Approximately 60-90% of individuals see a substantial improvement in symptoms with three to six months of physiotherapy.