Our shoulders are the most movable joints in our body. Most activities whether simple or strenuous engage both our shoulders. That is the reason why with a little bit of pain in our shoulders, we find it very difficult to do even the simplest of tasks like putting on a coat or carrying groceries. Sometimes there is a crunchy sensation or you may hear clicking and popping sounds while you move your shoulder or do weights. This pain can worsen making you feel frustrated, leaving your shoulders feeling weaker than normal and stiff to move. There could be many reasons for the cause of your shoulder pain but the most common injury that could possibly show these type of symptoms would be a rotator cuff injury.
What is the rotator cuff and how does it get injured?
The Rotator cuff is a group of muscles coming from the shoulder blade and ending in tendons that attach to the arm bone. These muscles cup the shoulder and are responsible for its stability during movement. The muscles of the rotator cuff muscles include:
- Teres Minor
“Centralisation”- Your rotator cuff is important
The function of the rotator cuff, in addition to generating torque, is to dynamically stabilize the shoulder joint. It keeps the ball of the shoulder centred over the small glenoid socket. Thus, stronger rotator cuff muscles result in the better glenohumeral joint stabilization and hold the humeral head into the glenoid by depressing it. This prevents impingement and decreased chances of shoulder dislocation when the deltoid abducts(arm sideways up) the shoulder. Without an intact rotator cuff, particularly during the first 60 degrees the ball of the shoulder would migrate up the glenoid cavity causing the rotator cuff attachments to get compressed by the acromion leading to impingement of the rotator cuff. In patients with large rotator cuff tears, the humeral head is poorly depressed and can migrate cephalad during active elevation of the arm.
Rotator cuff injuries
Sometimes sudden fall or high impact sports could be the cause of injury but in most cases, it is due to the repetitive injury over the tendons as they being pulled beyond their capacity to stretch. This gradually worsens causing partial or full tear of the tendons. Due to the way these tendons cup the shoulder by being closely spaced, they are more at risk of friction. Especially when you turn your shoulder or lift any weight at the end range of shoulder movement, the tendons in this tight space become taut and rub against the bony knob (acromion process of the scapula) above them or against a ligament at the front of the shoulder. This causes friction, pain and as a normal response, inflammation sets leading to pain, swelling and movement restriction.
Physiology of rotator cuff damage
1. Tendonitis (acute Inflammation)
Tendonitis can occur in a particular rotator cuff tendon causing pain, inflammation and irritation. If this condition becomes more chronic, more tendons can become involved or it may progress to a tendinosis (degeneration).
2. Impingement Syndrome (compression of the tendon)
The most common site of impingements is within the “supraspinatus outlet”. This outlet is a space formed by the acromion process of the scapula, the coracoacromial ligament and the upper rim of the humeral head.
Impingement within the outlet can be caused by:
- Thickened Coracoacromial ligament: This can cause impingement by becoming thickened due to excess calcium deposits that will compress the supraspinatus tendon.
- Hooked acromium: In repetitive overhead activities, the tendons rubs against the acromion process of the Scapula and gets damaged. When the inflammation spreads into the pocket of fluids (subacromial bursa) that lubricates the rotator cuff tendons under the acromion bone. This causes subacromion bursistis and the pain gets even worse on movements.
- Abnormal Scapular Movement: With normal shoulder movement, the scapula moves outward and upwards helping the shoulder to move up
- In the case of an unhealthy shoulder, the scapula does not move in the same fashion as the healthy shoulder and gets “stuck” in a lower position. This could lead to abnormal movement of the scapula during shoulder movement. Poor scapular movement will cause compression of the tendons in the supraspinatus outlet increasing the chances of impingement of the rotator cuff tendon that goes under it.
- The picture below shows an unhealthy right shoulder at a risk of impingement, showing improper movement in the scapula.
3. Rotator cuff tears
A tear is a result of the worsening of the tendon damage. Although an acute fall can tear the rotator cuff tendon, chronic inflammation and degeneration due to impingement is the major cause of tears. This tear can start small and get larger over time due to repetitive use or a re-injury. When a tear occurs, there will be severe weakness and atrophy(loss of muscle mass) of the muscles around the arm and loss of movements of the shoulder.
How is Rotator Cuff Injury Diagnosed?
Pain in the shoulder could be caused by various other reasons like joint injury, capsule injury, nerve problems and many more. A thorough examination of the shoulder should be done to distinguish the injury type. If a tear is suspected in the rotator cuff an MRI or an arthrogram (X-ray of the shoulder joint after injecting a contrast dye) can be taken.
Prevention and Management
A proper diagnosis and plan of management is necessary for the treatment and prevention of rotator cuff damage. Initial treatment would be pain relief, rest and avoiding any activity that aggravates pain in order to enhance the healing process. Further treatments will be decided upon the individual’s condition. Thorough assessment and planning by the experts with an application of knowledge of the condition and correct methods of treatment will promote recovery and prevent injury reoccurrence.