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Common Sports and Training Injuries: The Shoulder

Common Sports and Training Injuries: Shoulder Injuries

The Shoulder

The shoulder joint is composed of three bones – the clavicle (collarbone), the scapula (shoulder blade), and the humerus (upper arm bone). Your shoulders are the most movable joints in your body and can also be unstable because the ball of the upper arm is larger than the shoulder socket that holds it.

Because your shoulder can be unstable, it can be easily injured. Often, the first treatment for shoulder problems is RICE. This stands for Rest, Ice, Compression, and Elevation. Other treatments include exercise and medicines to reduce pain and swelling. If those don’t work, you may need surgery.

Bones

  1. humerus– the upper arm bone, articulates with the scapula above and the ulna below. Its proximal end forms a ball that articulates with the scapula, known as the glenohumeral joint
  2. clavicle- also known as the collarbone, is a curved bone that forms part of the shoulder complex; its lateral end articulates with the acromion of the scapula, and its medial end articulates with the sternum.
  3. scapula-  also known as the shoulder blade, is a triangular flattened bone articulating laterally with the clavicle. It also forms the socket of the glenohumeral joint

Articulations

  1. glenohumeral-the ball-and-socket joint connecting the humerus and the scapula
  2. sternoclavicular-the articulation between the clavicle and the sternum
  3. acromioclavicular the articulation of the clavicle and the acromion process of the scapula
  4. scapulothoracic-the articulation between the scapula and the dorsal ribs

Ligaments

  1. glenohumeral-three bands that reinforce the anterior portion of the shoulder joint
  2. sternoclavicular-a band that reinforces the sternoclavicular articulation
  3. acromioclavicular– two bands that reinforce the superior and inferior portion of the acromioclavicular articulation
  4. coracoclavicular– a band that reinforces the coracoid process of the scapula and the clavicle
  5. coracoacromial– a band that reinforces the coracoid process of the scapula and the acromion process of the scapula

Muscles

  1. deltoid– responsible for shoulder flexion, abduction, and extension
  2. pectoralis major and minor– responsible for shoulder adduction and horizontal adduction
  3. latissimus dorsi– responsible for shoulder extension and horizontal abduction
  4. teres major– responsible for shoulder extension
  5. rhomboid– responsible for shoulder adduction
  6. trapezius-upward rotation, elevation, and adduction of the scapula
  7. levetor scapula-elevation of the scapula
  8. serratus anterior-responsible for shoulder abduction
  9. biceps– responsible for elbow flexion and shoulder abduction
  10. triceps– responsible for elbow extension

Four Rotator Cuff Muscles (S.I.T.S.):

  1. supraspinatus-abduction and glenohumeral stabilization
  2. infraspinatus– external rotation, horizontal abduction, extension and glenohumeral stabilization
  3. teres minor-external rotation, horizontal abduction, extension and glenohumeral stabilization
  4. subscapularus– internal rotation, adduction, extension, and glenohumeral stabilization

Movements

  1. flexion– a movement of limb straightforward
  2. extension– a movement of limb straight backward
  3. adduction– a movement of a limb toward the mid-line of the body
  4. abduction– a movement of a limb away from the mid-line of the body
  5. internal rotation– rotary movement toward the body
  6. external rotation– rotary movement away from the body
  7. horizontal adduction– a movement of the humerus at 90 degrees of abduction toward the body
  8. horizontal abduction– a movement of the humerus at 90 degrees of abduction away from the body
  9. circumduction (multidirectional joint)- circular movement

Scapular movements:

  1. adduction (retraction)- a movement of the scapula toward the spine
  2. abduction (protraction)- a movement of the scapula away from the spine
  3. elevation– a movement of the scapula upward (shoulder shrugs)
  4. depression– a movement of the scapula downward
  5. upward rotation– a movement of the inferior angle of the scapula upward and laterally away from the spinal column
  6. downward rotation– returning the inferior angle of the scapula downward and medially; back to its normal position

Common Shoulder Injuries:

Impingement Syndrome

Involves the mechanical pinching of the supraspinatus tendon, the long head of the biceps tendon and the subacromial bursae. When the tendons/bursa become inflamed, less space is available for them to move through the coracoacromial arch (humerus and acromion). This condition occurs when the humerus is abducted above 90°.

Signs:

  • pain with abduction and external rotation above 90° (overhead activity)
  • pain in the subacromial space
  • pain at night; especially when trying to sleep
  • mild edema
  • weak external rotator muscle group
  • forced flexion, horizontal adduction and internal rotation tests are positive

Causes:

  • inflamed tendons/bursa decreasing the space in the coracoacromial arch when the humerus is abducted above 90°. Most commonly seen in overhead activities, such as throwing, swimming, and serving a tennis ball
  • hypermobility of the glenohumeral joint; if this ball and socket joint is unstable, the translation (increased movement) and resultant friction can cause an irritation to the surrounding tissues, potentially leading to rotator cuff strain and bursitis.
  • pre-existing rotator cuff weakness and/or injury or bursitis
  • postural deficiencies such as a forward head, rounded shoulders, and a hunched mid-back. These change the position of the bones and consequently decrease the space within the coracoacromial arch.
  • external rotator muscle group is too weak in relation to the internal rotator muscle group
  • tight posterior muscles and joint capsule
  • muscle fatigue
  • inadequate warm-up
  • poor biomechanics of the overhead activity
  • irregularly shaped acromion process (flat, curved, hooked, spurred)
  • fall on an outstretched arm (F.O.O.A.) or when the humerus is forced into an excessive position

Treatment:

  • moist heat or ultrasound prior to activity; keeping the shoulder warm during activity
  • stretch within a pain free range of motion, especially prior to activity   
  • apply ice after activity
  • electrical muscle stimulation
  • anti-inflammatory medication
  • strengthen weak muscles (external rotators, rotator cuff muscles, and scapular stabilizers)
  • core stabilization exercises can help to improve posture and shoulder joint mechanics
  • correct any postural deficiencies
  • joint mobilization to reduce capsule tightness
  • remedy poor biomechanics, to include training the components of the kinetic chain.  Proper throwing technique requires the use of the kinetic chain that begins with the legs, followed by the hips, torso, and then shoulder.
  • modify activity
  • return to activity gradually
  • may need to rest until symptoms resolve
  • surgery may be necessary to increase the space for the tissues to pass; most commonly an arthroscopic subacromial decompression is performed  

*bicipital tenosynovitis is also common with overhead activities. The long head of the bicep tendon sits in the bicipital groove of the humerus and is held in by the transverse humeral ligament. When the tendon and its synovial sheath become inflamed, the tendon can put too much pressure on the ligament and result in chronic tendon subluxations and/or tendon degeneration.

Rotator Cuff Strain/Tendinopathy

The four (4) rotator cuff muscles are the supraspinatus, infraspinatus, teres minor, and subscapularis. The acronym S.I.T.S. is often used to remember the names of the four muscles. The major purpose of the rotator cuff is to stabilize the humerus in the socket of the glenoid fossa (ball and socket joint), abduct and rotate the humerus. The supraspinatus is the most frequently injured rotator cuff muscle/tendon.

Signs:  

  • point tender pain on attachment to the humerus
  • pain with active and/or resistive range of motion
  • mild swelling
  • decreased range of motion in direction of injured muscle
  • decreased strength in direction of injured muscle
  • empty can test, drop arm test, and impingement test is positive

Causes:

  • overuse-overhead high-velocity rotation of humerus, such as throwing motions, tennis serves, volleyball spikes/serves, and the butterfly stroke in swimming.  It usually presents slowly over a period of weeks or months.
  • poor biomechanics; especially with overhead activities
  • hypermobility of the glenohumeral joint; if this ball and socket joint is unstable, the translation (increased movement) and resultant friction can cause an irritation to the surrounding tissues, potentially leading to impingement syndrome and bursitis.
  • pre-existing impingement syndromes or bursitis
  • postural deficiencies such as a forward head, rounded shoulders, and a hunched mid-back. These change the position of the bones and consequently decrease the space within the coracoacromial arch
  • muscle imbalance between the internal and external rotators
  • weak muscles that stabilize the scapula
  • tight rotator cuff muscles and/or joint capsule
  • muscle fatigue
  • inadequate warm-up
  • fall on an outstretched arm (F.O.O.A)
  • trauma forcing the humerus into an excessive position
  • rotator cuff tears are more common in people over the age of 40

Treatment:

  • moist heat or ultrasound prior to activity, and keeping the shoulder warm during activity
  • stretch within a pain-free range of motion, especially prior to activity   
  • ice after activity
  • electrical muscle stimulation
  • anti-inflammatory medication
  • strengthen weak muscles; rotator cuff muscles and scapular stabilizers
  • core stabilization exercises may be helpful to improve posture and shoulder, joint mechanics
  • correct postural deficiencies
  • joint mobilization to reduce capsule tightness
  • remedy poor biomechanics to include training the components of the kinetic chain; proper throwing technique requires the use of the kinetic chain beginning with the legs, hips, torso and then shoulder
  • modify activity
  • return to activity gradually
  • may need to rest until symptoms resolve
  • surgery to increase the subacromial space and/or repair the tear

Acromioclavicular Sprain (Separated Shoulder)

The clavicle is held to the acromion by the acromioclavicular ligament, and to the coracoid process by the coracoclavicular ligament. When these ligaments are sprained, the clavicle separates from the scapula. The degree of injury is based on the amount and direction of the instability, and the structures involved. There are six classifications (Type 1-6) of Acromioclavicular (AC) separations ranging from mild to severe.

Signs:

  • point tender pain on the AC joint and possibly on the sternoclavicular joint; considered one of the most painful shoulder injuries
  • pain upon most movements
  • swelling
  • decreased range of motion
  • a bump can be seen on the AC joint as a result of the upward displacement of the clavicle (Type 2 and above); the more damage to the ligaments, the greater the bump
  • AC traction test and AC compression tests are positive

Causes:

  • fall on the acromioclavicular joint (tip of the shoulder)
  • a direct blow to the acromioclavicular joint
  • fall on an outstretched arm (F.O.O.A.) or fall on an elbow
  • pre-existing rotator cuff injury

Treatment:

  • x-ray to rule out clavicle fracture and a weighted x-ray to determine the extent of separation  
  • sling to immobilize AC joint
  • ice to decrease pain and/or muscle spasm
  • anti-inflammatory medication
  • increase the range of motion with stretching exercises as tolerated
  • strengthening exercises and joint mobilization
  • brace and/or protective pad for activity
  • surgery- Types 1-3 usually don’t require surgical intervention, but Types 4-6 generally require surgical repair

 

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