Little League Elbow Syndrome


Over the past several decades, the number of organized sports for children has grown significantly, with millions of children participating in organized athletics each year. This increase in participation has been paralleled by an increase in sports-related injuries in the pediatric population. Emphasis on organized training and competition, as well as the seasonal nature of activity, has led to an increase in the number of overuse injuries. One type of overuse injury common in Little League baseball players is little league elbow, which is caused by repetitive throwing motion.

 

  • During the throwing motion, valgus stress is placed on the elbow. This valgus stress results in tension on the medial structures (ie, medial epicondyle, medial epicondylar apophysis, medial collateral ligament complex) and compression of the lateral structures (ie, radial head, capitellum). Repeated stress results in overuse injury when tissue breakdown exceeds tissue repair. Recurrent microtrauma of the elbow joint can lead to little league elbow, a term that encompasses the following group of disorders:

     

    • Medial epicondylar apophysitis

       

      • Delayed or accelerated growth of the medial epicondyle

         

      • Traction apophysitis (medial epicondylar fragmentation)

         

      • Avulsion of the medial epicondylar apophysis

       

    • Osteochondrosis and osteochondritis of the capitellum

       

    • Deformation and osteochondrosis of the radial head

       

    • Olecranon apophysitis with or without delayed closure

       

    • Hypertrophy of the ulna

       

    • Medial (ulnar) collateral ligament sprain

     

  • Medial epicondylar apophysitis and stress fractures through the medial epicondylar epiphyses caused by repetitive valgus stress generally present with progressive medial pain, decreased throwing effectiveness, and decreased throwing distance. Medial epicondylar avulsion fractures occur when a large acute valgus stress is applied during throwing. The above injuries present with point tenderness and swelling over the medial epicondyle, as well as an elbow flexion contracture often greater than 15°. Repetitive medial stress also can cause attenuation and microstretching of the ulnar collateral ligament complex, causing mild instability over time.

     

  • Lateral compression of the elbow results in osteochondrosis, as well as deformation and osteochondrosis of the radial head. Osteochondrosis of the capitellum generally occurs in children aged 7-12 years. These children complain of elbow swelling and a dull aching elbow pain that worsens with activity. Decreased range of motion (ROM) is uncommon. This type of injury starts with degeneration of the capitellum followed by regeneration and secondary calcification. Osteochondrosis manifests as a localized lesion of the subchondral bone and the overlying articular cartilage. This is a self-limited condition.

     

  • Osteochondritis of the capitellum, also caused by lateral compression, occurs in adolescents aged 13-17 years. These patients complain of a general dull elbow pain that worsens with activity, have a flexion contracture of 15° or greater, and exhibit decreased elbow extension. Loose body formation, residual capitellum deformity, and elbow disability are potential sequelae. This type of lesion can be separated into the following 3 types:

     

    • Type I has no displacement and no articular cartilage fracture.

       

    • Type II has evidence of articular cartilage fracture or partial displacement.

       

    • Type III is completely displaced with loose bodies in the joint.

     

  • Injuries to the olecranon also can occur because of repetitive throwing. During the follow-through stage of throwing, extension overload and valgus stress can result in injury of the olecranon. During childhood, the clinical presentation of the pathological conditions, osteochondrosis and osteochondritis of the olecranon, may include loose bodies and olecranon nonunion. These conditions can cause pain and locking in adolescents. Young adults additionally have injuries that result in partial avulsion of the olecranon or secondary osteophyte formation. These injuries may present with a limitation of elbow extension.

 

Frequency

United States

Annually, an estimated 4.8 million children aged 5-14 years participate in baseball and softball. The incidence of all baseball-related injuries is 2-8% per year. In the adolescent age group, the incidence of overuse injuries is estimated to be 30-50% of all injuries. However, the true incidence of sports-related injuries is unknown since a large number are treated at home or in an outpatient setting.

Functional Anatomy

Ligaments, capsular structures, and articular surfaces provide static stability of the elbow while musculoligamentous structures provide dynamic stability. The medial (ulnar) collateral ligamentous complex consists of the anterior oblique bundle, posterior oblique bundle, and transverse ligament. These structures are the primary medial support of the elbow during valgus stress. The lateral (radial) ligamentous complex, composed of the lateral collateral, lateral ulnar collateral, and accessory lateral collateral ligaments, provides support during varus stress. Additional static stability is provided by the ulnohumeral joint and the radial head.

Sport Specific Biomechanics

The pitching or throwing motion can be divided into 4 stages.

 

  • Windup consists of shifting the body weight to the ipsilateral lower extremity and coiling the lower extremities to potentiate energy release. Significant stress is not placed on the upper extremities.

     

  • The cocking phase begins with transfer of body weight to the contralateral lower extremity. The humerus is in extreme abduction and external rotation, and the elbow is flexed. During this phase, medial tension and lateral compression forces are applied to the elbow. Hyperextension and posterior medial sheer force also place stress on the olecranon.

     

  • Acceleration occurs when the throwing arm is "whipped" in the direction of the throw, resulting in lateral extension overload and tension of the medial ligaments.

     

  • Release and follow-through creates an avulsion stress at the origin of the flexor-pronator musculature as the forearm flexes and pronates, and the humerus internally rotates and adducts across the chest.