Rotator Cuff Injury

Common conditions, Injury, Pain

shoulder

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?

Rotator cuff injury

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:

  • Supraspinatus
  • Infraspinatus
  • Subscapularis
  • 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. Subacromial outlet

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

scaphumerorhythm movement

  • 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.

chances of impingement

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. impingement

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.

normal

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.

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Shoulder 101

anatomy, Exercise

shoulder

The main joint of our upper limb is the shoulder joint which can be moved in various positions when looked at in a three-dimensional perspective. In order to be able to have these movements, many other components help in order to maintain a stable shoulder. In short, there is a complex interplay between the shoulder joint, other joints, muscles and ligaments that make the shoulder a complex and unique part of our body.

Anatomy of the Shoulder Complex

The Shoulder complex consists:

  • The true joint called the Shoulder joint (Glenohumeral joint – GH)
  • The Clavicular joint with the scapula (Acromioclavicular joint – AC)
  • The Scapular joint with the body wall (Scapulothoracic joint – ST)
  • The Clavicular joint with the breastbone sternum (Sternoclavicular joint – SC).

The shoulder joint (GH) is made of two main bones that articulate with each other forming the ball and socket joint. The ball of the arm bone(humerus) and the glenoid cavity of the shoulder blade(scapula) is articulated at the shoulder joint (GH joint). Similarly, on the inner chest, the clavicle articulates with sternum to form the SC joint while on the outer end towards the shoulder the clavicle articulates with the acromion process of the scapula bone to form the AC joint. Both GH, SC and AC are true joints with union by fibrous, cartilaginous or synovial tissues. Lastly the ST joint, while this is not a true bony joint, its muscular attachments create a shoulder joint complex.SHOULDER

The humeral head (ball) is about three times larger than the glenoid fossa. Actually, only 25 percent of the humeral head articulates with the glenoid fossa. Glenoid cavity (fossa) forms a very shallow socket as compared to the hip socket of the hip joint. Therefore, the humeral head articulates with a smaller open and shallow saucer- type of articulation, lacking stability in its own. However, it is with all the soft tissue structures both inside and outside the joint that are responsible for the overall stability of the arm during movements.

Soft tissue structures that support the Shoulder Joint

The important soft tissue structures are:

  • Articular Cartilage
  • Labrum
  • Joint Capsule
  • Ligaments
  • Muscles

Articular Cartilage

A smooth, white tissue that covers the humeral head (ball) and the glenoid fossa to make it easier for the two bones to move at the joint. It allows the bones to glide over each other with very little friction.

Articular cartilage

Labrum 

Since the head(ball) of the upper arm bone is larger than the glenoid fossa, the articular cartilage forms a soft fibrous tissue rim called the labrum which surrounds the socket to help fit the head into it thus stabilizing the joint.

labrum

The socket can be divided into four regions namely anterior (front), posterior ( back), superior (the upper end near your head), and inferior (the lower end which is towards the elbow). Based on these regions the labrum is also called as superior, inferior, anterior and posterior labrum.

labrum 2

Joint Capsule

The shoulder joint capsule is a membranous sac that encloses the entire joint. The joint capsule of the shoulder is attached along the outside rim of the glenoid labrum of the glenoid cavity and attaches to the neck of the arm bone. The capsule by itself is quite loose and it is the surrounding reinforcement by the muscles, tendons, and ligaments that are largely responsible for keeping the shoulder joint stable.

capsule of the shoulder

Ligaments

In the shoulder, there is a group of ligaments that is responsible for the stability of the shoulder.

ligaments

Glenohumeral Ligaments (GHL)

This ligament attaches from along the outer glenoid socket covering the joint to the upper part of the arm bone.

  • Superior (upper) GHL
  • Middle GHL
  • Inferior (lower) GHL

Coraco-acromial Ligament (CAL)
This ligament attaches from the coracoid process to the acromion process of the shoulder blade (Scapula).

Coraco-clavicular Ligaments (CCL)
These two ligaments (trapezoid and conoid ligaments) attaches from the clavicle to the coracoid process of the scapula. This ligament can carry the load and is extremely strong. These tiny ligaments (with the AC joint) keep the stability between the scapula and the clavicle and thus keeping your shoulder ‘square’.

Transverse Humeral Ligament (THL)

This ligament protects the long head of biceps tendon muscle in the groove of the arm bone.

Muscles for the stability of the Shoulder Joint

Muscles of the shoulder connect the shoulder girdle, the clavicle and arm bone.

  • Muscles that origin from the spine and attaches to scapula and/or clavicle
  • Muscles that origin from the clavicle or scapula and/or body wall(ribs) to the top end of the humerus.

Trapezius, Levator scapulae, Rhomboids and Serratus Anterior

Originate from the base of the skull and/or spine and connect the scapula and clavicle to the trunk of the body.

traps, levator...

  • Trapezius forms cross-shaped web along the neck and run from the spinal column out to the shoulder blade and clavicle bone. It helps to shrug the shoulders.
  • Rhomboids and levator scapulae are important muscles that join the shoulder blade to the spinal column helping the scapular movements.
  • Serratus anterior muscle helps to stabilize the shoulder blade on the chest wall. When this muscle is weak, winging of the scapula occurs which is when the shoulder blade protrudes from the back.
winged scapula

Winged Scapula

Deltoid, Pectoralis major, Pectoralis minor, Latissimus dorsi, Teres major, Serratus Anterior

These arise from the clavicle and/or scapula and/or body wall and connect to the upper end of the arm (humerus) and anchor the shoulder joint to our body.

MUSCLES PECS

  • Deltoid muscle is a muscle that is responsible for overhead activities. It helps to move the arm sideways up.
  • Pectoralis major muscle like the deltoid is another powerful muscle which is the main muscle when doing push-ups. It originates from the front of the chest and collar bone and inserts on the upper part of the arm bone (humerus).
  • Latissimus dorsi is another powerful muscle that together with the teres major muscle pulls the arm down to the side. We use this muscle when doing chin-ups.

What are the Shoulder blade movements?

The muscles of the shoulder complex work together to perform a particular action. The Scapula and arm bone move together in a pattern to perform a movement.

The movements of the Scauplo-thoracic joint includes,

  • Depression – Downward arm and shoulder girdle movement
  • Elevation – Upward arm and shoulder girdle movement
  • Retraction – backward shoulder girdle movement
  • Protraction – forward shoulder girdle movement

movements in shoulder

Rotator cuff muscles- small in size, big in importance

The four rotator cuff muscles are important for the stability and movements of the shoulder joint. They are,

  • Subscapularis
  • Supraspinatus
  • Infraspinatus
  • Teres minor

Rotator cuff

These muscles connect the shoulder blade (Scapula) to the arm bone (Humerus) supporting the entire shoulder joint during movements.

The major function of the four rotator cuff muscles is to work simultaneously with each other to allow the arm to move freely in numerous positions. They do all this while pulling the humeral head downward and inward within the glenoid fossa.

Movements at the shoulder joint

The main movemnts at the GH joint are:

  • Flexion-Extension
  • Abduction-Adduction
  • Internal and External rotation

MOVEMENTS AT THE SHOULDER

  • Supraspinatus assists with lifting the arm with the deltoid above the head (abduction). This is the most common muscle / tendon to tear in the shoulder.
  • Subscapularis twists the arm behind (Internal rotation) the back.
  • Infraspinatus and the teres minor twists the arm outwards(External rotation) and sideways from the body.
  • Subscapularis assists with Deltoid, Biceps, coracobrachialis, Tere major to bring about shoulder forward flexion movement.
  • Triceps, latissimus dorsi, pectoralis major, teres major brings the arm backwards (Extension).

Why is the Rotator cuff is so important?

In order to prevent upward dislocation of the arm or tear within the inner soft tissue structures like labrum and capsule of the shoulder, balanced rotator cuff strength and function are necessary.  All the rotator cuff muscles work together stabilizing the humeral head within the glenoid while the larger muscles like the ltissimus dorsi, pectoralis major and deltoid produce the forces necessary for movements.

Common Injuries to the shoulder

  • Broken collar bone (Clavicle)
  • Dislocations of the shoulder
  • Frozen shoulder (Adhesive capsulitis)
  • Rotator cuff injury or strain (tendonitis or tendinopathy)
  • Acromioclavicular joint sprain
  • SLAP Tear (Superior Labrum Anterior Posterior tear)
  • Bankart’s lesion (Anterior inferior Labral tear, sometimes a part of the genoid cavity bone is also broken)

Most injuries to the shoulder are due to sudden trauma or repetitive trauma to the soft tissues and bones. Some of the injuries occur because of improper exercise selection, faulty technique, lack of warm-up, lack of dynamic stretches, dehydration and many more. However, knowing the anatomy and functions of the joints and soft tissue structures of the shoulder complex not only gives you a better understanding of it but will possibly give you a prospective as to how important is their role in maintaing the stability of the shoulder.