Australian Papers - Shoulder Impingement Part 4

Abstract

I began my study of the source of, and the treatment of, many forms of shoulder pain almost 20 years ago; as soon as i heard my anatomy mentor proclaim – “there is not one shoulder joint, there are four shoulder joints”, i was captured.

People presented at my clinic, reporting symptoms such as,( among others):

• Shoulder pain, in the vicinity of the lateral deltoid muscle.
• Restricted lateral abduction of the gleno-humeral joint.
• Some distal arm symptoms, such as a ”tingling”, or even a loss of grip strength.

A surprising number of these clients were armed with x-ray reports, that mentioned a possible tear of the supraspinatus tendon. In some other cases, comments were made about the condition of the sub-acromial bursa – it was obvious to even a simple manual therapist such as i, that the radiographer, either acting alone, or at the prompting of the physician that requested the x-rays, was focussing attention on the gleno-humeral joint – effectively ruling out all other possible causes of the reported symptoms. Indeed, it was not uncommon for most of these clients to proclaim that theirs was a “rotator cuff injury”

i commissioned an animated film of shoulder joint function, lasting about 20 seconds, which portrayed the movements of the scapula during full gleno-humeral abduction; when i showed this to an assembled group of medical practitioners in newcastle, they generally agreed – “this wasn’t taught at our medical school”.

So, you and i have reached the stage where we have reviewed shoulder function; in that review, we saw how the  gleno-humeral joint accounts for about 90 degrees of abduction; beyond the horizontal mark three other joints must be activated – the s.C., the a.C., and the s.T.
Unless these three joints function, as a team, impingement is a certainty.
Let us now speculate on the damage caused by impingement, and a recommended strategy for the client to adopt that might prevent its recurrence.

The Ideal Function.

I know I’m repeating myself, but here are posterior views of the gleno-humeral at various stages of lateral abduction:

The point of interest here is, for abduction to proceed beyond the horizontal, the scapula must rotate downwards; such a movement demands the stretch of at least two muscles, levator, and rhomboid. If either, or both, of these are contracted, this downwards rotation cannot occur.

Abduction beyond the horizontal will, in such circumstances, lead to impingement; portion of the upper humerus will collide with a portion of the scapula, crushing any tissue trapped between these two bony surfaces. Pain is the immediate result, and the shoulder area is on some degree of alert, and muscular contractions are one of the immediate by-products of such an alert.

The Damage.

Any contractions that were present in the levator and/or rhomboid before impingement occurred will now be confirmed; the client's GH abduction is certainly limited. Lateral deltoid use is restricted, and the muscle will quickly lose tone and strength. Contraction of any muscle leads, unavoidably, to compression of the nearest joint – levator contraction will compress the cervical spinal joints, which could account for the hand/wrist symptoms resembling brachiitis.

The x-ray reports, not just from my home town, but from around Australia, and the USA, regularly talk about signs of damage to the supraspinatus tendon – these reports, as well as scientific discussion papers refer to full or partial thickness tears. To my simple mind, if the supraspinatus tendon has suffered a full thickness tear, this could have a significant impact on GH abduction, but we need to ask ourselves, "what caused this apparent tear ? "

My theory is : as the tubercle approaches the acromion, (assuming the scapula is locked, and unable to rotate downwards), damage will be inflicted on :

• The inferior surface of the acromion.
• The tubercle itself.
• The sub-acromial bursa..
• The acromio-humeral ligaments.
• The gleno-humeral joint capsule, and
• The supraspinatus tendon.

Damage will not necessarily be caused to all of these structures, nor in this exact order, but sudden, or gradual abduction against a locked scapula will produce a significant "pinch" or "crush" of tissues. My other theory about these events is "when investigations are made, and radiographic or ultrasound photos are taken, the technician, or the physician, will focus on irregularities – seeking something out of the normal order of things".

If, for instance, there is an apparent imperfection in, say, the supraspinatus tendon, then it is tempting to deduce; "here is the cause of your discomfort". My proposition is: such noticeable soft-tissue damage could be a result of the injury, not necessarily the cause of the injury.

If the source of the client's pain has been identified as a torn supraspinatus tendon, then surgery in some form will be recommended; if, on the other hand, the cause is frozen shoulder, or, temporary failure of the scapulo-thoracic joint, initiated by contractions on say, levator scapula and/or rhomboidus, then a capable manual therapist can reduce or remove such contractions, thus freeing-up the ST joint. Surely it would be more sensible to postpone surgery, while the less-invasive manual therapy is tried ?

The Long-Term Strategy

What can be done to reduce the possibility of such contractions returning ? Why did they occur in the first place? A capable manual therapist could make his/her own deductions, but I have strong feelings that, in many instances, weakness in the lateral deltoid muscle will often promote an over-activity in the levator scapula, ( and often the upper trapezius).

Simple abduction exercises using 1 or 2 KG weights have in these instances, proved to be highly beneficial

The Landscape.

Here is a scene from parklands not far from our home – as this is government owned and controlled, and these animals are a protected species, their numbers are increasing rapidly, much to the concern of nearby landowners, who don’t share the opinion that kangaroos are cute.