Little leaguer’s elbow: a growing concern

While practice might make perfect, too much preparation can damage growing bones. Chris Mallac explains how pitching mechanics and skeletal immaturity contribute to little leaguer’s elbow.

2019 South Williamsport, PA, pitcher Egan Prather (24) throws a pitch in the third inning against the Caribbean Region during the Little League World Series. Credit: Evan Habeeb-USA TODAY Sports

Little league baseball games were once one of America’s favorite summer recreational pastimes. Today, there are over 200,000 little league teams in the United States, and the play is often serious⁽¹⁾. The growth in popularity and competitiveness of little league baseball and the increased opportunities to play year-round make young players ever more susceptible to overuse injuries.

A survey of 203 baseball players under 18 years of age found that nearly three-quarters of them experienced pain when throwing⁽¹⁾. Furthermore, 83% complained of pain the next day in their throwing arm⁽¹⁾. The increasing elbow stress from little league play has become a growing problem for young athletes who hope to one day make the majors.

Little leaguer’s elbow’ (LLE) usually refers to an injury to the medial elbow in a young throwing athlete.  Brogden and Crow first proposed this term in 1960, when they identified medial elbow fractures in young baseball pitchers⁽²⁾. However, the term little leaguer’s elbow now encompasses a host of injury patterns to both the medial and lateral elbow. An LLE may consist of a combination of the expected medial elbow trauma and an associated lateral or posterior pathology⁽³⁾.

Relevant anatomy

The adolescent elbow is unique in the number of ossification centers and cartilage physis that developing and fusing in chronological order as the athlete matures (see figure 1). Six primary ossification centers appear at various ages. These ossify and close sequentially so that the elbow is skeletally mature by the late-teens.

Figure 1: Appearance and closure of the ossification centers of the elbow^*

The ossification centers in the elbow are ordered and remembered using the mnemonic CRITOE, which refers to the capitellum, radial head, internal or medial elbow, trochlea, olecranon, and external or lateral elbow⁽⁴⁾. Note the particular vulnerability during the pre-adolescent and early adolescent years when many ossification sites are open. *Open Sourced from JAAOS Global Research & Reviews1(8):e040, November 2017.

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Signs and Symptoms

The clinical diagnosis for LLE is reasonably straightforward. It occurs in those youth and adolescent athletes who frequently throw and pitch. Pain is the most common complaint. The temporal pattern of pain also highlights if the injury is an avulsion type injury (acute onset of symptoms) or the more common apophysitis (longstanding and chronic type pain).

Differential diagnosis

Repetitive traction forces applied to the medial elbow by excessive valgus forces are the root cause of LLE. It occurs primarily in young baseball pitchers; however, it may also present in other sports that involve repetitive throwing actions such as cricket, water polo, and javelin. Although the diagnosis of LLE encompasses a range of injuries at the elbow, damage to the medial aspect is the most common feature of this syndrome (see table 1). In fact, medial epicondyle fractures are the third most common type of fracture in children⁽⁵⁾. The high rate of medial side damage is likely because the medial epicondyle epiphysis is one of the last epiphysis to fuse at around 16-17 years of age in males (earlier in females)⁽⁶⁾.

Table 1: Differential diagnosis of little leaguer’s elbow⁽⁶⁾

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Imaging

Plain films may show widening or distal displacement of the medial epicondyle. Consult a surgeon if the apophyseal separation is more than three to five millimeters⁽⁴⁾. An MRI can be used to view early edema on the medial apophysis or in the ulnar collateral ligament (UCL) itself. Confirm suspected sprains or tears of the UCL with an MRI or ultrasound⁽⁷⁾.

Researchers at the University of California conducted a cohort study of 26 adolescent baseball players⁽⁸⁾. The athletes underwent baseline MRIs and physical exams, which were repeated three years later. After three years, the study found that 58% of the players had pathology in their throwing arm. Eighty percent of these were new or progressive findings since their baseline study. Those who played baseball year-round were more likely to have a positive physical exam and significant MRI findings.

Management

A treatment plan for a youth suffering from LLE:

1. Unload and rest the arm for four to six weeks, usually without splinting or casting. Elbow flexion and extension are allowed in pain-free positions but avoid any valgus force.
2. Use pain and inflammation-reducing medications to calm down an aggressive inflammatory process.
3. Continue with strength training for the legs, hips, and trunk muscles to improve force production in these areas. Baseball pitchers must generate a considerable amount of force from the hips and trunk to reduce the shoulder and elbow load. Weak pitchers who underuse the hips and trunk will overcompensate with a greater windup and pitching sequence, placing undue stress on the medial elbow.
4. Perform shoulder rotation and scapular strength training to improve shoulder girdle stability.
5. Return to pitching after six to eight weeks with modified pitch counts.

The impact of pitching mechanics

The baseball pitch is divided into six stages (see figure 2). The greatest tensile force on the elbow occurs during the late cocking phase when the shoulder reaches full external rotation and the elbow is flexed. In the acceleration phase, the elbow experiences a valgus load equal to 4.6% of the young baseball pitcher’s bodyweight⁽⁹⁾. The valgus strain allows the medial side to ‘open up’ and subjects the medial growth plate to a high shear load.

The forearm flexor and pronator muscles also exert a strong pull on the unfused bone in the acceleration phase and can contribute to an avulsion injury. While adult pitchers may strain the ulnar collateral ligament, the UCL’s attachment site at the medial apophysis is more vulnerable in young players^(10,11).

The radius and capitellum of the humerus also experience compressive and shearing forces during a pitch. Repetitive application of these forces can cause osteochondritis dissecans (OCD) of the capitellum. Osteochondritis dissecans is a localized area of necrosis that can lead to fragmentation of the bone and is classified as a Salter-Harris type V fracture. Thus, injuries may occur to both the medial and lateral side of the elbow^(12,13).

The highest incidence of LLE occurs in nine to 14 year old’s when the epiphysis on the medial epicondyle is still unfused and prone to damage from high traction forces. At this age, players become more enthusiastic about pitching, the game becomes more competitive, and pitching counts start to accelerate. They are also the most susceptible to faulty technique as sudden growth spurts change the arm bone’s leverage and length⁽¹⁴⁾. It takes the muscles time to lengthen in response to the skeletal growth and strengthen to support the longer lever arm. Young athletes who continue to pitch with faulty kinematics during this time are more vulnerable to injury⁽¹⁰⁾.

Figure 2: The baseball pitch

The pitch is divided into six stages: windup, stride, cocking, acceleration, deceleration, and follow-through^(10,11). Of the 6 phases, the windup and stride are the most important as they form the foundation of pitch mechanics. Better technique during these phases generates more force from the legs, hips, and trunk and minimizes the strain on the arm (see table 2).

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Verbal Cue	Description
Lead with the hips	During the stride phase, the pelvis leads the trunk toward home plate.
Hand-on-top position	Place the throwing hand on top of the ball as hands separate in the stride phase.
Arm in the throwing position	Time maximum shoulder abduction to coincide with foot contact in stride.
Closed shoulder position	Lead shoulder points toward home plate at foot contact in stride.
Stride foot toward home plate	At foot contact, the stride foot points toward home plate.

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Pitching Load

Little leaguer’s elbow is essentially an overuse injury caused by excessive pitching loads and high-load pitching styles. Therefore, a large part of the prevention of LLE is to limit the pitch numbers in games and training and to introduce pitch types at appropriate developmental ages. The USA Baseball Medical and Safety Advisory Committee suggests guidelines regarding the number of pitches and types of pitches for a player depending on their age (see table 3).

The highest load pitch is known as a breaking pitch, and children should not throw these until they reach skeletal maturity. Pitchers should not compete for more than nine months each year and avoid all overhead activities during the three months of rest. In addition, discourage pitchers from after-game pitching practice and participating in more than one league during overlapping seasons.

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Age (years)	OK to throw	Pitches per game	Pitches per week	Pitches per season	Pitches per year
2021-08-10 00:00:00	Fastball	50	75	1000	2000
2021-11-12 00:00:00	Change-up	75	100	1000	3000
13-14	Curve	75	125	1000	3000
15-16	Slider, forkball, splitter, knuckleball	90	-----	-----	3000
17-18	Screwball	105	------	-----	-----

This table represents a chronological age progression.  As some youths mature faster than others, the youth may be slotted into an earlier or later age group based on developmental age or their baseball league’s rules.

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Conclusion

Little leaguer’s elbow is a generic term that denotes more than one definitive pathology of the youth pitching elbow. Specifically, it is a throwing-related apophysitis of the unfused ossification center on the elbow’s medial epicondyle. It is a common injury caused by excessive pitching and pitching many breaking type pitches. Adolescent growth spurts and relative weakness in the hips and trunk muscles also contribute to the development of LLE. Treatment requires complete arm rest while building strength around the legs, hips, trunk, shoulder, and scapula. Emphasize correct technique during this stage as the immature and growing skeleton makes young pitchers even more vulnerable to injury.

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