Creekside Physio Blog

The Rotator Cuff – Rotator Cuff Syndrome

Posted on: May 17th, 2017 No Comments

The rotator cuff is the popular term for four muscles whose primary job is to stabilize the shoulder in its mid-range of motion. The shoulder joint, is that between the humerus (upper arm bone) and the scapula (the shoulder blade and the joint’s surfaces are not a great fit. The surface of the humerus, the head is much less rounded than it’s partner the glenoid so between them they form a ball and socket joint that is, by itself very unstable, but that instability allows it to have a very large range of motion.

Figure 1. Image courtesy of Visible Body

A number of features help stop the joint from dislocating every time you use it. First, there is a ring of fibrocartilage that encircles the glenoid and make it much less shallow but because the ring is deformable it does not limit normal movement very much.


Figure 2. Image courtesy of Visible Body

Figure 3. Image courtesy of Visible Body

Second is a joint capsule that is reinforced by ligaments that will stabilize the joint near it’s end of range so that you can safely put your arm behind your back and over your head. But the main stabilizer for mid-range motion is the rotator cuff.

Figure 4. Image courtesy of Visible Body

Figure 5. Image courtesy of Visible Body

The rotator cuff is made up of four muscles running between the shoulder blade: they are supraspinatus, infraspinatus, subscapularis and teres minor.

Figure 6. Image courtesy of Visible Body

The picture to the left (Figure 6) is of the back of the shoulder and it shows supraspinatus as the top muscle then infraspinatus and at the bottom teres minor. In addition to stabilizing the shoulder, the supraspinatus lifts the arm away from the side while the infraspinatus and teres minor rotate it outwards so that the thumb points away from the body.

Figure 7. Image courtesy of Visible Body

The picture to the right (Figure 7)  shows the subscapularis muscle which is attached to the entire underside of the shoulder blade and runs in front of the humerus to attach to the inside of the bone at the front of the shoulder. When it contracts it rotates the arm inwards so that the thumb points backwards.

While these muscles do help produce motion their most important function is to keep the head of the humerus from traveling across the surface of the glenoid. They achieve this because of their orientation. As you can see from this picture from the side of the shoulder these muscles are orientated such that when they contract as a group they will tend to pull the head of the humerus into the glenoid.

Figure 8. Image courtesy of Visible Body

When working perfectly the head does not translate at all during active movements, it just sort of skids in place, but when the muscles are not performing properly the head can translate across the glenoid and stress adjacent structures particularly the labrum. In addition this abnormal movement can allow one or more of the tendons to become pinched between the humerus and the scapular, the so-called impingement syndrome.

These muscles can become weak due to prolonged pain, pinched or inflamed nerves, partial or complete tears, inadequate neural feedback due to reduced movement (reflex inhibition). And this can result in small muscle and tendon tears, inflammation and atrophy.

They can also become painful due to pinching by adjacent structures (impingement syndrome) and this can in turn be caused by structural abnormalities and altered biomechanics, degeneration of the tendon or muscle by altered blood flow or prolonged over-use, sudden unfamiliar over-use all of which may cause a tendonitis.

In addition, all of the components of the shoulder girdle must be optimally involved in shoulder movements especially throwing activities, swimming and lifting weights. The upper back must be able to bend backwards, the acromioclavicular joint (right on top of the shoulder) must be mobile and the joints between the upper back and lower back must be able to rotate freely if the person is twisting the body to throw. In more ballistic throwing activities the hips, knees and feet must also be able to rotate to generate force.

If any of these structures are not moving as well as they should extra stress is thrown on those that are and the shoulder joint seems to take the brunt and break down.

Assessment for a Specific Diagnosis

Rotator cuff syndrome just won’t do as a treatment diagnosis as the problem is rarely if ever all four muscles. Most commonly I find that the infraspinatus and/or supraspinatus are at fault but the other two can also be the problem(s). To ascertain which muscle(s) are involved requires very specific and careful palpation of the tendons and muscles followed by stretching and contracting them for pain and weakness. Of the examination techniques palpation is the most difficult not just to make sure that you palpating the correct tendon but also to allow for the fact that overlying and underlying tissues such as other muscles and bursa can be excluded from the diagnosis. The picture below shows just how complex this can be.

Figure 9. Image courtesy of Visible Body

To the left (Figure 9) is looking down on a fully muscled shoulder. About a third of the way up the picture is the deltoid, this overlays the entire shoulder joint and all of the attachments of the rotator cuff muscles, this must be palpated through.

The small bluish patch just above it is a bursa. The main function of the bursa is to reduce friction, you can picture them as two sheets of cling film between which is a very small drop of olive oil which allows the sheets to slide over each other. They can become inflamed and this is a bursitis.

Above the bursa is the upper part of the trapezium muscle and this overlies the supraspinatus muscle and must be palpated through to get to the supraspinatus muscle belly.

Figure 10. Image courtesy of Visible Body

The deltoid and trapezius have been removed in Figure 10 so that you can see the next layers that are palpated. The blue patch is the subdeltoid and subacromial bursae and laying under them are the attachments of the supraspinatus, infraspinatus and teres minor muscles so this must also be palpated through before the tendons can be reached.


Ideally contraction/stretch tests specific to the tender tendon will reproduce the patient’s pain  but less ideally only the palpation test may be positive in which case very sensitive palpation is required to differentiate pathology of the bursa from the tendon.



1. Find the Causes

The rotator cuff problems are fairly easy to treat providing the cause is determined and dealt with. Treating a tendonitis is only of temporary help if the underlying cause is not corrected at the same time. So the therapist should carry out an extensive biomechanical assessment of the upper quarter that includes the neck, shoulder girdle (shoulder joint, acromioclavicular joint, the joint between the scaplula and the chest wall, the joint between the breast and collar bones (sternoclavicular), the upper back (thoracic spine). Additionally this examination should also include an examination of the neurological system looking for compressed or otherwise damaged nerves and of the muscles looking for all types of weakness and changes in muscle tone. Once this examination has been carried the therapist then needs to consider the findings to make sure that they are relevant to your painful tissue and work out a plan of treatment. This usually involves manipulative therapy, muscle stimulation with needles or shockwave, exercises and stretching. By far this is the most difficult part of treating the problem.

2. Deal with the Pathology

Not all tendon problems are tendinitis, that is inflamed tendons sometimes the tendon is degenerate rather than inflamed. This degeneration may be caused by prolonged over-use, inadequate blood supply repeated but moderate pinching and loss of nutrition due to nerve compression. Small tears may also occur due to weakness from any cause and while they may not cause immediate pain accumulate scar tissue which can over time or with the appropriate trigger become painful. These are termed tendonosis.  Tendonitis, that is actual acute inflammation of the tendon  is caused by diseases such as gout, arthritis etc or more commonly by unfamiliar obvious over-use such as painting a house, playing ball once a year and so on. The pain of tendinitis is much more severe than tendonosis and almost no palpation is necessary to cause a lot of pain. The differentiation is important from both the physician’s and physiotherapist’s perspective. Anti-inflammatories including injections have little if any effect on a tendonosis while many of the mechanical treatments in the physiotherapist arsenal such as shockwave may increase the pain of the tendinitis.

Shockwave is perhaps the most effective treatment for a tendonosis while high dose ultrasound may be better for the tendinitis. Interferrential current therapy (IFC) can be very useful and reducing the pain and inflammation of tendonitis and tendonosis. Friction massage (properly deep transverse friction massage) is an older treatment whereby the tendon is compressed and rubbed across it’s length is an effective treatment but has probably been displaced by shockwave in those clinics that own this treatment. Neither treatment can be called comfortable but they do work and Shockwave actually does have experimental evidence supporting it.

3. Rehabilitation

Once the pain is reduced to reasonable levels that do not affect movement and once the causes and contributing factors are dealt with rehabilitation can be started. This tends to be a prolonged an obtrusive treatment because to restore normal movement patterns takes considerable repetition and the movement can only be repeated for as long as it is done near perfectly otherwise all you do is practice doing it wrong and you can get very good at this.


See your physio if any shoulder pain shows no sign of improvement after two or three days or if it is getting worse; the sooner you find the cause of your shoulder pain and get started on treatment the less muscle weakness will occur and so the less long term problems will plague you. It is also much easier to t

reat recent pain onset than when it has been there for a longer period.

Make sure you therapist is able to tell you which tissue is in trouble and whether it is a tendonitis or a tendonosis and ask what treatment they intend to give you based on their diagnosis.

Your therapist should be able to determine if you need anti-inflammatories or not and refer you to your doctor for them.

I hope this short item helped you to understand “rotator cuff syndrome” and understand the treatment options available to you from you therapist.

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