Supraspinatus Tendonitis

Supraspinatus tendonitis is a common shoulder problem, also known as “Shoulder Impingement Syndrome” or “Painful Arc Syndrome”.

Shoulder impingement syndrome is the most common problem with one-in-five people having symptoms at some point in their lives.

Supraspinatus symptoms may come on suddenly after an injury, or build-up gradually on and off over years with no obvious cause. 

The classic sign of supraspinatus tendonitis is a painful arc when moving the arm between 60-120 degrees of abduction as the tendon gets squashed against the bone in that range. 

Symptoms of painful arc syndrome typically begin in middle-age, most frequently between the ages of 45-65.

Typically, supraspinatus tendonitis is an overuse injury caused by repetitive friction on the tendon, but it can be caused by a shoulder injury, instability or shoulder impingement.

To compensate, four muscles, known collectively as the rotator cuff, work together as the key dynamic stabilising muscles of the shoulder – supraspinatus, infraspinatus, teres minor and subscapularis. 

The rotator cuff muscles arise from the scapula and their tendons attach to the head of humerus, underneath an arch formed by the acromion process - a bony projection at the top of the scapula that forms a joint with the clavicle aka collarbone.

Supraspinatus lies across the top of the shoulder blade. The supraspinatus tendon passes through a narrow channel between the acromion and the head of the humerus, known as the “sub acromial space”.  

The subacromial space and is only around 7-14mm deep  and is tightly packed with the:

• Supraspinatus Tendon
• Subacromial Bursa: a fluid filled sac that helps reduce friction through the subacromial space
• Joint Capsule: the upper part of the sac that surrounds the joint
• Long Head of Biceps Tendon

The subacromial space is narrows considerably when the arm is raised around shoulder height, particularly when internally rotated (thumb pointing down). The space then opens back up once the arm is raised higher and externally rotated (thumb pointing up).

Common symptoms of painful arc syndrome include:

• Shoulder Pain: A deep aching, burning pain at the top and front of the shoulder and outer arm at rest which may radiate down the mid upper arm but rarely to the elbow. There may also be a sharp, catching pain when reaching up or moving the arm out to the side, or when twisting

• Painful Arc: An arc of pain, usually between 60-120^o of shoulder abduction, when lifting the arm out to the side.
  Movement in this range, both lifting up and lowering down is typically extremely painful, but outside this range movement is often pain-free. 
  This is the classic symptom of supraspinatus tendonitis, hence the name “Painful Arc Syndrome”
  
  
• Shoulder And Arm Weakness: Considerable weakness or weakness with no pain indicates a full thickness rotator cuff tear aka supraspinatus tendon full thickness tear
  
  
• Functional Limitation: Any activities at or above shoulder height may be painful and restricted e.g. reaching up to a cupboard, hanging up washing and washing/brushing your hair
  
  
• Sleep Disturbance: night pain is common with supraspinatus tendonitis, especially when lying on the affected side
  
  
• Full PROM: Whilst pain may limit active shoulder movement, passive movement (where the arm is moved by someone else so your muscles are completely relaxed) is typically full or nearly full with pure supraspinatus tendonitis as long as there are no other shoulder impingement problems. 

Suprapsinatus tendonitis can usually be diagnosed by your doctor or physical therapist by talking to you about your symptoms and examining your shoulder. If a partial or full thickness tear of the supraspinatus tendon is suspected, you may also be sent for an MRI or ultrasound scan.  

Typical tests that are used to diagnose supraspinatus tendonitis are:

1. Hawkins Kennedy Test
   Position: Arm supported in 90^o shoulder and elbow flexion
   Test: Forearm pushed downwards to internally rotate shoulder. Test is repeated bringing arm into different positions of adduction across the body
   Positive Result: Pain in the shoulder 
   
   
2. Empty Can Test aka Jobe’s Test
   Position: Both arms raised to 90 degrees abduction and 30 degrees forwards flexion, thumbs pointing to ceiling
   Test: Rotate arms so thumbs pointing down. Examiner pushes down through forearms while patient resists the movement
   Positive Result: Pain in the shoulder

If no pain is reported with either of these tests, then supraspinatus tendonitis is most likely not the problem.

Transverse frictions are a specific type of connective tissue massage delivered transversely across the tendon fibres. When done correctly, deep transverse friction massage helps to reduce pain and inflammation with supraspinatus tendonitis, speed up healing of the damaged tendon and improve function by:

• Hyperaemia: Increasing local blood flow to the area
• Local Heat Effect: raising the local temperature 
• Removing Chemical Irritatants: which would otherwise sensitize local nociceptors so pain receptors are less easily irritated
• Decrease Local Oedema: reducing swelling in the tendon 
• Mobilise Adhesive Scar Tissue: helps to prevent the formation of adhesions and breaks down unwanted scar tissue and abnormal cross-fibres in the supraspinatus tendon. This helps to realign the damaged tendon fibres in the correct position and improves tensile strength

This helpful video from The Benjamin Institute shows the correct technique for deep transverse friction massage for suparaspinatus tendonitis.

A common misconception is that Deep Transverse Friction Massage is painful, but when done correctly this is not the case.

Gentle pressure is used initially across the supraspinatus tendon until the area becomes numb, known as the analgesic effect. At this point the depth of pressure is gradually increased without inducing pain. The length and frequency of treatment will depend on the stage of injury.

Transverse friction massage should only be carried out by a trained professional such as a physical therapist as success relies on a good knowledge of anatomy and structural organisation of the tissue so that they can be applied to the exact site of the supraspinatus tendonitis lesions, in the correct direction and at the right depth for the appropriate duration and frequency.

8. Shoulder Surgery

Less than one quarter of patients will require surgery for supraspinatus tendonitis, even if there is a full thickness tear in the tendon.

But if the symptoms of supraspinatus tendonitis have failed to resolve after 3-6 months of conservative treatment, then shoulder surgery may be recommended.

This tends to be when there are other pathologies alongside supraspinatus tendonitis such as subacromial bursitis, bone spurs and/or rotator cuff tears. 

Subacromial decompression surgery is the most common option to open up the subacromial space and is combined with a rotator cuff repair if the supraspinatus tendon is torn.