The Shoulder

The shoulder is a complex structure that is comprised of 4 joints: glenohumeral (GH), acromioclavicular(AC), sternoclavicular(SC) and the scapulothoracic, which is a muscular ‘joint.’ The trade-off for having a structure with such a great range of motion is that it is highly unstable and susceptible to various types of injury due to that. The rotator cuff muscles, which you have probably heard of, are very important for the shoulder’s overall health and function. Their strength and flexibility directly determine the shoulder’s stability.

When someone separates their shoulder they are referring to an injury of the AC joint, the point where the collar bone articulates with the acromion of the shoulder blade. Falls onto the point of the shoulder or onto an outstretched arm can cause this separation. Depending upon severity, it is often treated with a Kenny-Howard sling and no overhead movements are allowed for 4-6 weeks.

Impingement syndrome can have many causes, but the most common would be a weakness of the rotator cuff muscles. Their function is to keep the head of the arm bone (humerus) tightly compressed against the socket of the shoulder blade. Failure to do this results in the head riding upwards and causing compression of a bursa and often, a rotator cuff muscle tendon as well. Pain is created when the shoulder is lifted past 90 degrees and these structures are most compressed. Assuming this is caught early enough, rest and rehab of these muscles with specific exercises will cure it.shoulder If, however, somebody must repeat an overhead aggravating motion repetitively due to their sport ( swimmer, baseball pitcher) or occupation ( painter, electrician, for example), then the tendon will become fibrotic and thicken and becomes a permanent lesion. At this point extensive rehab is required to get out of pain and regain function. The third stage of impingement syndrome involves tearing of the tendon, either partially or fully. These cases aren’t necessarily surgical, however, conservative care may be effective as well, but are evaluated on a case-by-case basis.

Falls can result in a dislocation of the humeral head. Due to the anatomy and how all is attached in this area, the GH joint tends to dislocate forwards and will be obvious with the amount of pain it creates, the bump that will be apparent as the humeral head sits outside its joint and finally, the lack of proper mobility the individual will have. A dislocation in the other direction is much more innocuous and can go relatively unnoticed until they are asked to do a specific test to look for it.


Frozen shoulder is a condition more common in middle-aged women whose exact cause is unknown. We know that the lining of the GH joint capsule thickens and doesn’t have proper synovial fluid flow, but why this occurs is a mystery. The condition goes through 3 stages: freezing, frozen and thawing, the time-frame for which can last around 2 years, if left untreated. The freezing stage is the most painful although there is no true loss of range of motion. The frozen stage involves a lack of proper mobility of the GH joint, particularly lifting it to the side (abduction). After several months the shoulder will start to ‘thaw’ and the person will progressively regain their mobility. It is possible, however, that it may not return to full range.  Treatment of the rotator cuff muscles, both hands-on work and strengthening exercises, such as pendulum exercises, can help. Application of heat at home prior to stretching can aid a better stretch. Here’s a video of a few exercises you can work on:

As mentioned, the shoulder is a complex joint and the conditions outlined above are only a very few of those possible. If you are dealing with shoulder pain get it properly evaluated and diagnosed so you can be on the road to recovery as soon as possible.



Dr. Mark Strudwick is a third-generation chiropractor in Victoria, B.C.


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