The infraspinatus tendon lies just behind and below the supraspinatus tendon in the subacromial space and is one of four tendons that together are known as the rotator cuff. The infraspinatus muscle sits in the lower part of the shoulder blade at the back of the shoulder and it turns the arm outwards, most obviously when the elbow is bent to 90°.
Infraspinatus tendinopathy is usually caused by overuse and the pain is felt at the back of the shoulder when performing the outward movement against some resistance and on lifting the arm up as in waving to someone, when a pinch of pain may be felt at shoulder height.
Physiotherapy can help with treatment including a specific massage technique to the painful area, called frictions, and mobilisations. Activities that aggravate the pain should be avoided initially but exercises will be given that improve the strength of the infraspinatus muscle and tendon and help to stabilise the shoulder. Electrotherapy may be used, particularly ultrasound. Advice will also given on posture to help to prevent recurrence. In cases that don’t respond to this conservative management, an injection may be given, usually into the subacromial bursa that blends with the tendon rather than directly into the tendon itself. In the case of tendon rupture, where the arm will be functionally more weak than painful, a surgical opinion will be appropriate.