Little League Elbow Syndrome

Updated: Aug 30, 2018
  • Author: Holly J Benjamin, MD, FAAP, FACSM; Chief Editor: Craig C Young, MD  more...
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Little league elbow (LLE) syndrome is a valgus overload or overstress injury to the medial elbow that occurs as a result of repetitive throwing motions. 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. [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12]

Increased single-sport participation with year-round training, higher intensities at young ages, and longer competitive seasons are contributing factors to the increased injury rates seen in pediatric athletes. [13] Conditioning and training errors also contribute significantly to the risk and frequency of injury. Although briefly discussed below, injuries to the lateral, posterior, and anterior elbow are separate entities and should not be confused with the medial injuries referred to as little league elbow syndrome.

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 syndrome that encompasses (1) delayed or accelerated growth of the medial epicondyle (medial epicondylar apophysitis), (2) traction apophysitis (medial epicondylar fragmentation), and (3) medial epicondylitis. [1, 8, 14, 15, 16, 17]

Medial epicondylar apophysitis and stress fractures through the medial epicondylar epiphyses caused by repetitive valgus stress generally manifest with progressive medial pain, decreased throwing effectiveness, and decreased throwing distance.

Other causes of medial elbow pain include avulsion fractures of the medial epicondyle and ulnar collateral ligament (UCL) sprains or tears. Although a fracture is usually an acute traumatic event, a preceding history of medial elbow pain is common and is thought to be a risk factor for progression to acute fracture. Therefore, any thrower who is experiencing medial elbow pain should refrain from pitching until he or she has had a thorough evaluation. [1, 3, 5, 8, 18]

A medial epicondyle fracture manifests as point tenderness and swelling over the medial epicondyle, often with an elbow flexion contracture greater than 15°. Repetitive medial stress can also cause attenuation and microstretching of the UCL complex, causing mild instability over time. [1]

UCL injuries can manifest as acute ligament tears following a single valgus stress or as overuse sprains following repetitive valgus overloads. The clinical presentation is similar to little league elbow; however, the typical age range of the athlete is the older teenager who is skeletally mature. Suspected UCL injuries should be referred for further evaluation by a sports medicine specialist. Athletes with UCL injuries should not be allowed to pitch until they have been evaluated.

Although uncommon in children, neurologic injuries such as C8-T1 radiculopathy and ulnar neuritis can manifest as medial elbow pain and should be included in the differential diagnosis (see Differentials and Other Problems to Be Considered).

Lateral compression of the elbow most frequently results in injuries to the capitellum and radial head. Osteochondrosis of the capitellum (known as Panner disease) generally occurs in children aged 7-12 years and manifests as dull, achy, activity-related lateral elbow pain. Swelling, clicking, and decreased range of motion are uncommon associated symptoms. Panner disease tends to be a benign self-limited condition that does well over time and is treated with complete rest from inciting activities such as throwing and weight bearing on the elbow. Osteochondral injuries can also be observed in the radial head.

Osteochondritis dissecans (OCD) of the capitellum occurs in adolescents aged 13-17 years. This is a localized injury to subchondral bone that results from repetitive lateral compression of the elbow during overhead motions. These patients report a general dull elbow pain that worsens with activity, often have a flexion contracture of 15° or greater, and may have mechanical symptoms of clicking or popping. Loose body formation, residual capitellum deformity, and elbow degenerative joint disease are potential sequelae. Different treatment options are used based on the age and skeletal maturity of the patient and the type of lesion present.

Osteochondritis dissecans lesions can be separated into type I, which has no displacement and no articular cartilage fracture; type II, which has evidence of articular cartilage fracture or partial displacement; and type III, which is completely displaced with loose bodies in the joint.

Posterior elbow injuries also occur as a result of throwing. During the follow-through stage of throwing, extension overload and valgus stress can result in injury of the olecranon. These athletes present with posterior elbow pain, clicking, and possible loss of elbow extension. Loose bodies and olecranon nonunion can occur in younger athletes. Older athletes may experience olecranon fractures or secondary osteophyte formation. These injuries are sometimes treated surgically. [1, 3, 4, 5, 6, 7, 9, 10, 11, 19]

For excellent patient education resources, visit eMedicineHealth's First Aid and Injuries Center. Also, see eMedicineHealth's patient education article Repetitive Motion Injuries.




United States

Annually, an estimated 4.8 million children aged 5-14 years participate in baseball and softball. The incidence of all baseball-related overuse injuries is 2-8% per year. The incidence of overuse injuries in the 9- to 12-year-old range for baseball is 20-40%, and in the adolescent age group is 30-50%. The true incidence of sports-related injuries is unknown because a large number of athletes never seek medical care. Early recognition of little league elbow syndrome is important, because it leads to better outcomes and decreases the risk of persistent functional disabilities in the athletes.


No data are available for the annual incidence of little league elbow syndrome in the international community.


Functional Anatomy

Evaluation of the young adolescent elbow presents some anatomic challenges to the healthcare provider in that the elbow consists of numerous ossification centers and cartilaginous physes. Becoming familiar with the chronologic order of appearance and ossification of these growth centers is important. Consider the mnemonic CRITOE (ie, capitellum, radius, internal epicondyle, trochlea, olecranon, external epicondyle).

Each of the ossification centers appears at a relatively predictable time starting around age 1-2 years, with 2-year intervals between the next center's appearance. Closure of each of the apophyses occurs from age 14 to 16 years, with the medial epicondyle specifically closing at approximately age 15 years. The elbow likely reaches full skeletal maturity by the late teen years, at which time injuries to the UCL are far more common. Until then, the young thrower is at risk for little league elbow syndrome. [1, 4, 14, 18, 20]

The static stabilizers around the elbow include the bony articulations, the joint capsule, and the various ligament bundles. 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.

The dynamic stabilizers primarily include the muscles that cross the elbow joint, such as the triceps, biceps, and brachioradialis. The flexor-pronator group stabilizes against valgus stress, and the extensor-supinator group stabilizes against varus stress.

Elbow biomechanics include flexion/extension range of motion and pronation/supination. Slight hyperextension 5-15° through flexion of approximately 150° is within normal limits. Baseball pitchers with years of throwing experience often have relative 5-10° flexion contractures on their dominant side; however, in the young thrower, a flexion contracture can be a sign of injury. Pronation of 75° and supination of 85° is normal. Varus-valgus laxity of 3-4° is normal.


Sport-Specific Biomechanics

One should be familiar with the stages of throwing to understand the complexities of the biomechanical forces that contribute to the young thrower's risk of injury, such as in little league elbow syndrome. The pitching or throwing motion can be divided into 6 stages. Medial elbow injuries are the most common type seen in throwers and occur most commonly in the cocking and acceleration phases of throwing, owing to the presence of maximum valgus extension or distraction forces. [1, 14, 15, 16, 17]

  1. Windup begins with the pitcher balancing his weight over his rear leg, with the elbow flexed and the forward leg flexed at least 90°.

  2. Stride starts with the lead leg beginning to descend toward the plate, and the 2 arms separate. The elbow moves from extension into flexion of 80-100°.

  3. Cocking occurs when the humerus is in extreme abduction and external rotation and the elbow is flexed. The lead foots contacts the ground, the pelvis and trunk rotate, and elbow torque transfers valgus force across the elbow joint. During this phase, medial tension and lateral compression forces are applied to the elbow.

  4. Acceleration is the shortest pitching phase, lasting from maximal external shoulder rotation to ball release. In this phase, the trunk rotates as the elbow extends. Maximum elbow angular velocity is comparable during fastballs, sliders, and curveballs, but it less during the change-up pitch. Velocity comes from rotation of the trunk, shoulder, and hips. Varus torque forces during this phase act to resist the valgus extension "overload" phenomenon and can contribute to posterior elbow (olecranon) impingement.

  5. Deceleration is initiated at ball release and ends when the shoulder has reached full internal rotation. The body must decelerate the arm and dissipate forces in the elbow and shoulder.

  6. Follow-through is the final phase of the baseball pitch and ends with the pitcher reaching a balanced fielding position with full-trunk rotation and the body weight fully transferred from the rear leg to the forward leg. During follow-through, the elbow flexes into a relaxed position and crosses the body.