Little Leaguer’s Shoulder

Cuba’s national youth baseball pitcher Oscar Hernandez warms up before a friendly game against Japan at the Latinoamericano stadium in Havana, Cuba.

Youth participation in baseball and other overhead sports continues to rise worldwide. With this growth comes an increasing incidence (~8% per year) of Little Leaguer’s Shoulder, also known as proximal humeral epiphysiolysis — an overuse injury of the proximal humeral physis in skeletally immature athletes⁽¹⁾. Little Leaguer’s Shoulder most commonly affects baseball pitchers aged 11–16 years, but any youth athlete engaged in repetitive overhead activity may be at risk, such as tennis, badminton, and cricket^(1,2,3).

Although usually self-limiting, mismanagement risks recurrence, chronic pain, and, in rare cases, growth plate complications. For physiotherapists and sports clinicians, a thorough understanding of the biomechanics, risk factors, and evidence-based management of Little Leaguer’s Shoulder is crucial.

Pathophysiology and Epidemiology

The proximal humeral physis accounts for 80% of humeral growth and remains open until 16–21 years of age⁽⁴⁾. Repetitive overhead motions, such as throwing (baseball) or serving (tennis), place rotational torque across this vulnerable growth plate, resulting in microtrauma and progressive physeal widening^(4,5).

Approximately 5% of youth baseball players develop radiographic evidence of Little Leaguer’s Shoulder(6). Risk factors include year-round play, single-sport specialization, early introduction of breaking pitches, glenohumeral internal rotation deficit (GIRD), and excessive pitch/serve counts (see table 1)^(1,7).

Table 1: Risk factors for Little League’s Shoulder and clinical correlates

Athletes complain of a gradual onset of lateral shoulder pain with throwing or serving, often without a discrete injury event. They may also report fatigue, weakness, or referred elbow pain(1,4). Clinicians should keep Little Leaguer’s Shoulder in the differential diagnosis for adolescent athletes presenting with shoulder pain, alongside rotator cuff and bursal pathology.

Beyond Baseball — Other Sports at Risk

• Cricket: Case reports confirm Little Leaguer’s Shoulder in fast bowlers; the whip-like delivery produces stresses similar to pitching⁽³⁾.
• Tennis: MRI studies in elite adolescents show growth plate changes and early rotator cuff pathology, even in asymptomatic athletes⁽⁷⁾.
• Badminton: A case report describes an elite junior player with a proximal humeral epiphyseal stress fracture following intensive training, highlighting the risk of overuse in racket sports⁽²⁾.
  
  

Diagnosis

Clinical assessment remains central. Localized tenderness over the proximal humerus and pain with resisted rotation are common findings⁽⁴⁾. Radiographs typically reveal widening of the proximal humeral physis (Salter-Harris type I) in the dominant arm. While clinicians increasingly use MRI to confirm diagnoses and identify coexisting pathology, such as labral or rotator cuff changes (8,9). However, asymptomatic MRI abnormalities are common in youth throwers and overhead athletes, emphasizing the need to interpret imaging in the context of the clinical presentation^(7,9).

Clinical Red Flags

• Persistent pain despite three months’ rest.
• Premature growth plate closure on imaging.
• Mechanical symptoms (clicking, instability) suggesting co-pathology.

“More than 90% of athletes achieve full recovery, and complications are uncommon.”

Management

Little Leaguer’s Shoulder is best managed nonoperatively:

• Rest: Cessation of throwing or serving for ~three months^(3-5).  
• Physiotherapy: Clinicians should address GIRD, strengthen rotator cuff and scapular stabilizers, and correct kinetic chain deficits.
• Return to throwing: Athletes must only begin throwing when pain-free with full strength and range of motion. Repeat imaging is unnecessary, as radiographic recovery lags behind clinical improvement⁽¹⁰⁾. Importantly, clinicians must create structured, graded programs to reduce the risk of recurrence⁽⁴⁾.
• Return to serving: Similar to throwing, athletes must progress gradually. They can start with slice serves (~10 reps at ~70% RPE), then move to flat, and finally kick serves, increasing volume and intensity stepwise⁽⁶⁾.
• Outcomes: Most athletes return to full sport within four to six months. Recurrence occurs in 7–19% of cases, particularly in those with persistent GIRD^(1,4). 

Long-term Prognosis

More than 90% of athletes achieve full recovery, and complications are uncommon. However, in rare cases, complications include premature physeal closure and chronic shoulder pain⁽⁴⁾. These risks underscore the importance of early recognition, adequate rest, and adherence to throwing guidelines.

Prevention

The most effective strategy is prevention: 

• Follow age-based pitch counts and mandated rest days (see table 2).
• Ensure at least one seasonal break from throwing each year⁽⁶⁾.
• Identify and correct GIRD early.
• Promote multi-sport participation to reduce repetitive stress⁽⁷⁾.
• Encourage close collaboration between clinicians, physiotherapists, coaches, and parents.

Practical Prevention Tips

• Track pitch/serve/bowling counts across all teams.
• Teach sound throwing and serving mechanics early, with emphasis on kinetic chain efficiency.
• Delay breaking pitches (curveballs, sliders) and limit kick serves until skeletal maturity.
• Screen annually for deficits in range of motion and eccentric strength.

Table 2: USA Baseball pitch count recommendations (ages 7–16)