When Shoulder Instability was first Recognised:
Shoulder instability has not been new , and has been recognised over 3000 years ago on Papyrus in Egypt. Hippocrates used the old fashioned technique of placing a heel in the axilla of the unfortunate injured person and applied traction and with various degrees of success helped to “put the shoulder back in the right place.
Dynamic Anatomy of Shoulder Instability
There are a group of Static stabilisers including:
The Dynamic Stablisers include:
- Glenohumeral Ligaments
- Coracohumeral Ligaments
- Negative pressure (which helps “suck in arm to shoulder”.
- The rotator cuff
- Scapula stabilisers.
Anatomy of Instability
Instability happens when one of the above structures goes wrong eg the labrum a soft tissue lining that cloaks the joint may weaken, as it also is the anchor for ligaments.
There is good news as when we age this shoulder bone stiffens and becomes stronger reducing the propensity to disclocation.
The ligaments above the joint (the superior glenohumeral ligaments act as a restraint fo inferior/ posterior translation
The middle gleno humeral ligaments act as a restraint for inferior translation and also limits external rotation.
Testing the Shoulder
For any shoulder issue a general range of motion is done to see how far the shoulder will move, along with seeing how strong all the particular strengths and range of movements are: (external rotation, internal rotation, flexion and extension).
The patients overall laxity must also be assessed. Generally as an overall test for laxity the mobility of fingers, thumbs, elbows, knees and palms to ground is assessed. A score of above 6 indicates hyper-mobility. This is often found in conditions such as Marfans and Ehler’s – Danlos syndromes.
The other tests that are done are X Ray , MRI arthrogram, and CT arthrogram.
Types of Instability
Shoulder instability leading to anterior dislocation is at 90% the most common, which affect 2% of the population, around 90% of these occur under the age of 20, 14% recur after the age of 40.
Posterior dislocation comprise only 2 -5% of shoulder dislocations in such cases patients are unable to externally rotate their arm.
Surgery For Recurrent Dislocations
If a shoulder dislocates too often or recurs then surgery should be considered. This is particularly the case when there is structural pathology and when this occurs ligaments can be tightened , and any looseness of the joint capsule repaired.
What Can Be Done Before Dislocation?
If a shoulder shows signs of instabilty there are plenty of shoulder strengthening exercises that can be done to address this issue.
Osteopathy and Acupuncture
Are very useful tools that can help both help ensure better stability, and is helpful in the post surgical rehabilitation where there might be residual stiffness and awkwardness in movement.