Let’s start off with a brief overview of shoulder anatomy…

The shoulder is comprised of four different joints: the glenohumeral joint, scapulothoracic joint, sternoclavicular joint and the acromioclavicular joint. In simple terms, the glenohumeral joint is where the humerus (arm) bone connects into the socket of the shoulder. The scapulothoracic joint is where the scapula or shoulder blade meets with the thoracic spine. The sternoclavicular joint connects the rib cage to the clavicle (collar bone). The acromioclavicular joint is where the acromion process of the scapula (shoulder blade) connects to the clavicle (collar bone). In essence, the shoulder is how the arm, scapula, clavicle, and sternum and all work together to allow movement.



From a musculoskeletal standpoint, there are a few major muscles that are necessary for healthy shoulder movement. The most commonly known is the rotator cuff. The rotator cuff is a group of four muscles that have the responsibility of keeping the humerus within the glenoid cavity. These four muscles are the supraspinatus, infraspinatus, teres minor, and subscapularis. Three of the four rotator cuff muscles allow the arm to rotate outward and the fourth allows the arm to rotate inwards. They all must work synonymously to keep the humerus stable in the cavity.



Within the glenoid cavity sits the labrum. This is a fibrocartilaginous disc that sits on the rim of the glenoid fossa and is responsible for deepening the cavity and providing a “suction-like” seal to keep the head of the humerus in the fossa and avoid dislocation. The biceps brachii muscle is inherently important as well because of its origin of the long head of the biceps. The long head of the biceps attaches into the labrum which can create the potential for decreased stability and further room for structural damage.

Outside of the glenoid cavity is the capsule of the shoulder. Think of this being the “saran wrap” around the shoulder to help keep it in place. The capsule is a tissue that can become more stiff or loose (also called laxity) depending on the forces placed on it. This becomes very important when looking at shoulder stability.

Within the shoulder, there are multiple bursa sacs that help to reduce friction and provide cushion for the bones. The bursa can become inflamed in the shoulder which creates acute pain because there is less space for the tendons to fit and move.



The shoulder is a ball and socket joint and is one of the most mobile joints within the body… therefore making more room for potential injury. If the scapula does not provide accessory stability and work together with the rest of the shoulder, movement is not going to be balanced and will lead to the potential of a few different types of injuries. The scapular muscles are comprised of the rhomboids, latissimus dorsi, teres major, trapezius, levator scapulae, and serratus anterior. These all have an attachment to the scapula and are responsible for an upward or downward rotation and/or protraction or retraction. If these muscles have a strength imbalance compared with the rest of the shoulder musculature, most likely there will be some type of shoulder pain or damage in the front (anterior) part of the shoulder.



What does shoulder stability mean?

To keep it simple, shoulder stability means the head of the humerus stays within the socket of the shoulder with an appropriate amount of mobility. It means that all of the shoulder muscles are working together to keep the shoulder together!

So what does it mean if the shoulder is unstable?

Again for simplicity, shoulder instability means there is a strength imbalance that allows the shoulder to slip out of the socket (sublux) and/or dislocate. It can be due to a multitude of reasons and usually is always related to more than one.

Common Shoulder Injuries due to Shoulder Instability

Rotator Cuff Strain

Labrum Tear

Biceps tendinitis

Bursitis

Shoulder Impingement

A rotator cuff strain is going to occur when the shoulder is placed in a position in which the rotator cuff muscles are working hard to keep the shoulder in place and the forces are greater than the strength of the rotator cuff. This means that one or more rotator cuff muscles has been “stretched out” or potentially partially or completely torn. Typically, if there is not a complete tear, corrective exercise and strengthening will be sufficient for recovery from this injury. If there is a complete tear, surgical intervention would be necessary.

A labrum tear occurs when the shoulder subluxes or dislocates. When the head of the humerus comes out of the glenoid cavity, the shearing force will cause a tear to the labrum which sits on the rim of the glenoid fossa. There are different types of tears that can occur to the labrum. Usually, once the shoulder has subluxed or dislocated once, it is more susceptible to it happening again. Not only does the labrum accrue damage, but the capsule of the shoulder becomes stretched out as well and now has more potential for shoulder instability. Surgery to repair the labrum is typically recommended for those individuals that have reoccurring dislocations.

Biceps Tendinitis is more of a chronic shoulder injury in which there is a repetitive stress occurring that is irritating the biceps tendon. Usually this goes hand in hand with a muscle imbalance and shoulder instability that ends up causing the tendinitis. With this type of injury, making the corrections to build strength and stability in the shoulder is essential to alleviate pain and irritation to the biceps tendon. Treating just the biceps tendon and trying to reduce pain and chronic inflammation will only work for so long. As soon as the repetitive forces are placed on the shoulder again, the injury will likely come back.

Bursitis within the shoulder is a similar concept to biceps tendinitis in that there is a repetitive stress causing the irritation to the bursa. This is usually do to shoulder instability again that is causing less space in the anterior portion of the shoulder and the bursa is then becoming inflamed. Treatment for this injury needs to also utilize corrective therapy to make the lasting changes so the injury does not continue to occur.

Shoulder impingement is also in the same category as tendinitis and bursitis. The difference is that a rotator cuff tendon is becoming “pinched” or trapped in either the anterior or posterior portion of the shoulder because of shoulder instability. To “fix” the impingement, the shoulder muscles needs to be working together to glide within the cavity properly to allow proper space for the tendons. Corrective therapy will be the fix for this injury as well!

What about posture? I have heard that I should work on sitting up straight more and not be hunched over?

Posture is HUGE for shoulder health. HUGE! But… there is a lot more to it than just simply sitting up straight. To have good posture, the musculature needs to be strong enough to hold the correct posture on its own without having to “try to sit up straight”. It takes corrective therapy which involves strengthening, stability and mobility work to improve posture in the long term. Without proper posture, there is an increased chance for injury. The anterior musculature will become tight, the posterior musculature will become weak and a chain of issues will occur. Working on improving posture is the best way to prevent shoulder injuries.

So what should I be doing to prevent or improve shoulder instability?

KINECT with us so we can teach you how to make the improvements! We want to help you reduce the risk of injury, reduce pain, and get you back to doing all of the activities that you love without any issues! Understand that to create a more stable shoulder, it does take work and commitment. There is NOT a quick fix to shoulder injuries. Decreasing pain is very important, but not as important as correcting an issue to make a lasting change. Our goal at Kinect Health is to improve quality of life… not just for today, but for the future!

In the mean time… here are a few corrective exercises you can do to help with shoulder instability.



Lat Pulldowns

You will need a band, cable, or lat pull machine to do this exercise. Make sure the shoulders are relaxed down and you are squeezing the bottom of the shoulder blades together when you pull back. There should not be any tension in the upper trapezius muscle (top of shoulders/neck). You should feel this exercise in your mid back. Perform 3 sets of 10-15 reps.



Supine Foam Roll Stretch

Lay on top of a long foam roller so that your head is resting on the foam roller. Place both arms out to the sides with palms facing upwards. Lay in this position for 3-5 minutes. If numbness or tingling starts to occur in the hands, you can bring both arms down by your sides.



Plank with Renegade Row

Start off in a plank position with hands on dumbbells. Make sure the core is tight and back is not rounded or sinking towards the floor. While shifting weight onto one side, perform a row with one arm making sure to think about squeezing the bottom of the shoulder blade towards the spine and relaxing the neck. Perform the same movement with the other arm. Perform 3 sets of 10-15 reps.