Shoulder Instability

The shoulder joint is a highly mobile joint. Unlike the hip joint which is a ball in a deep socket, the top of the humerus (long bone of upper arm) articulates on the glenoid (a part of the shoulder blade) and resembles a ‘golf ball on a tee’. Shoulder instability refers to excessive movement of the humeral head on the glenoid, resulting in pain, dislocations, or apprehension. People may be fearful of this instability, and worried about further injuries - either traumatic or non-traumatic. 

Why is shoulder stability important?

The shallow joint in the shoulder enables us to move our shoulder through great ranges of motion, giving us the capacity to reach overhead, behind our back and out to the side. Due to the lack of bony congruence, the shoulder relies heavily on surrounding soft tissues such as the rotator cuff muscles, labrum, joint capsule and ligaments for stability.

The 4 rotator cuff (RC) muscles arise from different aspects of the shoulder blade (scapula) and attach to the humerus. They merge and blend in tightly with the joint capsule, which is further reinforced by the labrum, coracohumeral and glenohumeral ligaments. The labrum is a fibrocartilaginous rim surrounding the glenoid that deepens the socket, providing extra stability.

Physio or surgery for Shoulder Instability?

Non-operative conservative management (i.e. physiotherapy) should be the primary intervention for treating shoulder instability. Exercise has been shown to improve shoulder pain and function just as effectively as surgical treatments in both the short and long term. Therefore, a minimum trial of at least 3 months physiotherapy should be performed before considering surgery, especially for those with atraumatic dislocations. Staying patient during the initial trial is important as it takes approximately 12 weeks for significant improvements to be noticed2. Avoiding surgery in this time will significantly reduce the odds of having surgery later down the track.

‘‘But my scan says I have a Cabral or rotator cuff tear… surely I will require surgery to fix it!?’’

Rotator cuff tears are common findings in people without shoulder pain or disability. Surgery may not improve shoulder pain or function compared with exercise therapy in small to medium atraumatic degenerative rotator cuff tears. 

Who are more likely to get shoulder dislocations?

Males are approximately 2.5x more likely to get shoulder dislocations than females4. In particular, males in the 16-20 years old age bracket have the highest rates of dislocations, potentially due to more risk-taking behaviours. Interestingly, the incidence of dislocation significantly increases in women over the age of 50, but this trend is not observed in men. The majority of shoulder dislocations are seen in the active population and are due to sporting injury, with anterior dislocations being the most common.

Given that shoulder dislocations can compromise the structural integrity of the shoulder, it is of no surprise that history of a previous dislocation is a big risk factor for future episodes. Conditions affecting connective tissue integrity such as generalised joint hypermobility, Marfan’s and Ehlers Danlos syndromes may predispose people to instability and recurrent dislocations. Patients with these conditions are most likely to present with recurrent dislocations without any significant pain or traumatic event. The Beighton score for hypermobility is a quick and easy tool that can screen for such connective tissue disorders.

What can I do to improve my prognosis?

Engaging in a structured, progressive shoulder strengthening exercise program for a minimum of 12 weeks is highly likely to provide good functional outcomes. Physiotherapy advice on activity modification and how to deal with flare ups or manage symptoms is important throughout this process. Staying positive, patient and trusting in the process (and your shoulders ability) is key. Addressing modifiable factors such as limiting alcohol consumption, weight loss and improving diet and sleep can assist in the natural healing process.

If you have any questions on whether physio is the best option for you, or you have any questions about MVMNT in general, feel free to contact via email.

- Jay Towolawi, Specialist Sports Physiotherapist and MVMNT Founder.