‘Shoulder Pain when turning Arm Outwards – Infraspinatus Tendon Strain’
An achy and sometimes sore pain into the tip of the shoulder and the outer area of the shoulder blade may be caused by a strain of the infraspinatus tendon. The Infraspinatus tendon is one of 4 rotator cuff tendons that help stabilize the shoulder joint. It is also responsible for turning the shoulder outwards (external rotation), moving your arm behind the head and finally helps when extending the arm backwards. It attached from the shoulder blade to the outside tip of the head of the shoulder (humerus head).
Mechanism of Injury
The infraspinatus is injured when the muscle contracts or tightens while it is a lengthening position. An example of this is clipping a hedge or any overhead work for a prolonged period of time. When the arms are held in an elevated position, the infraspinatus tendon is thus held in a stretched position. Then an action of moving the arms outwards and inwards occurs (externally rotation the shoulder joint – the role of infraspinatus) causes the tendon to contract (tighten) while it is in a stretched position. When done repetitively a strain or tear of the tendon can occur.
Shoulder Pain Signs & Symptoms
Pain located at the outside tip of the shoulder can refer downwards to the outside area of shoulder blade.
Patient experiences a sharp jab of shoulder pain when reaching the arm in a forward plane to answer the phone or when reaching their arm outwards to carry a tea-pot.
Soreness or an Ach when driving the car with hands resting on the top of the steering wheel or when changing gears.
Difficulty & weakness lifting the arm upwards and downwards from an elevated position.
An ach can be present when attempting to sleep on that shoulder at night.
Treatment & Management
Improving the position of the shoulder blade from forward tilting is important in order to reduce the abnormal stretch of the Infraspinatus tendon. I find manual Graded Frictioning of the deposits of scar tissue formation at the site of the tendon attachment to humeral head very beneficial. In addition, Postural exercises are very important to help reduce shoulder slouching. Finally, isometric early stage strengthening on infraspinatus tendon with arm in neutral which further progresses to higher grades of strengthening once an improvement is achieved.
Tomás Ryan is a Registered Physical Therapist with The Irish Association of Physical Therapy (MIAPT) and is based in Thurles. Contact Number: 0504 26672