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Basics ⬇

Author(s): MikeLaGrange, MD, FAAFP, CAQSM and TracyRay, MD, FACSM, CAQSM

Description

  • Also known as thrower’s shoulder
  • Remodeling and deformation of the proximal humeral physis
  • Overuse injury from recurrent, excessive torque placed on the growth plate
  • Typically seen in overhead athletes, especially adolescent baseball pitchers; results from recurrent, excessive overhead activity
  • First described in 1966 as osteochondrosis of the proximal humeral epiphysis and then reported again in 1974 as proximal humeral epiphysiolysis in adolescent baseball players

Epidemiology

  • Uncertain exact prevalence due to underreporting of pain with throwing
  • Most common in male baseball players between ages of 11 and 16 yr
  • Has also been reported in swimming, volleyball, and cricket
  • Can occur in any adolescent athlete involved in repetitive overhead rotational activities

Etiology and Pathophysiology

  • Unknown exact etiology
  • Biomechanical studies have revealed shear stress arising from high torque during late cocking phase is large enough to lead to deformation of the proximal humeral growth plate.

Genetics

No known genetic disposition

Risk-Factors

The following risk factors are based on expert opinion because no studies have evaluated this to the author’s knowledge:

  • Year-round pitching without 3 mo of rest from throwing during the course of the year
  • Playing in multiple leagues at the same time
  • Going over recommended age-specific pitch count for game, season, or year (1)[C]
  • Inadequate rest between pitching outings
  • Improper throwing mechanics
  • Throwing with a fatigued shoulder

General Prevention

Prevented by avoiding excessive, repetitive overhead activities; having adequate rest between outings; and not throwing with shoulder fatigue or pain

Diagnosis ⬆ ⬇

Diagnosis based on history, physical, and classic radiographic findings

History

  • Patients typically complain of pain while throwing or with overhead activity.
  • Pain with throwing is typically constant throughout throwing cycle.
  • Most commonly presents with pain laterally over the proximal humeral physis but can present with diffuse pain all over shoulder or referred pain to upper arm
  • Insidious onset of pain
  • Patients may report recent increase in number of pitches thrown or recent change to playing on a larger field.

Physical Exam

  • Typical physical exam finding is tenderness to palpation over the proximal humeral physis without erythema, increased warmth, or soft tissue swelling.
  • Can present with painful range of motion, including pain with abduction or forward flexion >150 degrees
  • Can present with decreased strength of the rotator cuff musculature secondary to pain. Most common is reduced strength and pain with resisted external rotation.
  • Can have reduced internal rotation of the shoulder due to posterior capsular tightness, but this finding can also be normal in an adolescent overhead athlete and is not pathognomonic for injury

Differential Diagnosis

  • Rotator cuff tendonitis/impingement
  • Multidirectional instability
  • Labral tear (usually superior labrum anterior posterior [SLAP] tear)
  • Salter-Harris type I fracture of the proximal humeral physis
  • Biceps tendonitis
  • Osteochondral fragment of the glenoid

Diagnostic Tests & Interpretation

  • Standard x-rays are the diagnostic gold standard.
  • Ultrasound can be helpful and can help to document tenderness at the physis.
  • Anteroposterior of the affected shoulder in external rotation and internal with comparison films of the unaffected side are standard.
  • Typical findings are widening of the affected growth plate, especially on the lateral side of the growth plate.
  • May also see osteolysis and cortical irregularity of the bone surrounding the physis
  • Although not required for diagnosis, magnetic resonance imaging (MRI) will also show widening of the growth plate on the T1-weighted images with possible extension of signal into the metaphysis on T1 and gradient echo images.

Treatment ⬆ ⬇

General Measures

  • Treatment consists of rest from throwing and limited use of over-the-counter (OTC) pain medications such as acetaminophen or nonsteroidal anti-inflammatory drugs (NSAIDs) as needed for pain (2)[C].
  • Recommend rest from throwing for 3 to 12 mo (3)[C].
  • Physical therapy during rest period should focus on rotator cuff strengthening, core muscle strengthening, and improved range of motion at the shoulder.
  • Recommended to complete an interval throwing program after finishing physical therapy or 3-mo rest before returning to full activity

Medication

Age-appropriate dose of any NSAID or acetaminophen can be used as needed for pain during initial period of rest.

Surgery/Other Procedures

No surgical correction required

Ongoing Care ⬆ ⬇

Follow-up Recommendations

  • After 3- to 12-mo rest/physical therapy to reassess exam and give guidance on starting an interval throwing program
  • Repeat x-rays are not necessary because it can take up to a year for growth plate to return to normal.

Patient Education

  • Patients, parents, and coaches should be educated on age-appropriate pitching recommendations, including pitch counts and age restrictions on throwing specialty pitches.
  • Should also stress importance of not throwing with a fatigued arm or painful shoulder because this can lead to future injury

Prognosis

Patients treated with appropriate rest have an excellent long-term prognosis.

Complications

Alteration of throwing mechanics from throwing with pain may lead to other injuries, such as labral tears or injuries to the elbow of the same arm.

Additional Reading ⬆ ⬇

DiFiori JP, Benjamin HJ, Brenner JS, et al. Overuse injuries and burnout in youth sports: a position statement from the American Medical Society for Sports Medicine. Br J Sports Med. 2014;48(4):287–288.

References ⬆ ⬇

Little League. Regular season pitching rules—baseball and softball. https://www.littleleague.org/playing-rules/pitch-count/. Accessed October 17, 2018.

  1. Shanley E, Thigpen C. Throwing injuries in the adolescent athlete. Int J Sports Phys Ther. 2013;8(5):630–640.
  2. Arnold A, Thigpen C, Beattie PF, et al. Overuse physeal injuries in youth athletes. Sports Health. 2017;9(2):139–147.

Clinical Pearls ⬆

  • An adolescent should never throw with shoulder pain or fatigue.
  • Loss of velocity or pitch control during an outing are signs of shoulder fatigue.
  • Pain with external rotation and pain along physis can indicate thrower’s shoulder.