The Shoulder in Youth Baseball

1
The Shoulder in Youth Baseball

• Koco Eaton, M.D.

2
Little Leaguers Shoulder

• Originally described by Dr. Dotter in 1953
• Best described as a stress fracture of the
  proximal humeral physis
• Overuse inflammation of proximal humeral physis
  vs. stress fracture of physis

3
Little Leaguers Shoulder

• Mechanism
• Appears to be caused by rotational stress applied
  to proximal humeral physis during act of throwing
• During throwing, shoulder is forcibly internally
  rotated and adducted from an externally rotated
  abducted position
• Results in repetitive microtrauma caused by the
  large rotational torques needed to throw

4
Little Leaguers Shoulder

• Mechanism
• Growing bones are very vulnerable to injury from
  repetitive microtrauma because of the weakness of
  the growth plate compared to the attached muscles
  
• Once the growth plates fuse, the athlete is more
  likely to injure ligaments and tendons
• Overuse injuries occur when tissue breakdown
  exceeds repair

5
Little Leaguers Shoulder

• Crockett, Gross, Wilk et al, AJSM 2002
• Adaptive remodeling
• High-level baseball pitchers have greater
  external rotation and less internal rotation in
  their dominant shoulder compared to the
  nondominant shoulder and the shoulders of
  nonthrowers
• Adaptive remodeling occurs at the proximal
  humeral physis of skeletally immature athletes in
  response to muscular forces and torques that
  accompany pitching

6
Little Leaguers Shoulder

• Adaptive remodeling
• Increases external rotation and reduces
  impingement of the rotator cuff on the glenoid
  rim
• Helps create the anatomy necessary to become an
  elite pitcher as an adult, but does not mean that
  it allows unlimited throwing in the skeletally
  immature athlete
• Young thrower's safe and successful development
  straddles a fine line between overuse and
  appropriate use

7
Little Leaguers Shoulder

• Risk Factors
• Position played (pitcher, catcher, outfield, 3rd
  base, shortstop)
• Higher than recommended number of throws
• Nine to 12 months of play in a year
• Poor pitching mechanics
• Throwing pitches too advanced for age

8
Little Leaguers Shoulder

• Symptoms
• Gradual onset of pain in throwing shoulder
• Localized to proximal humerus during throwing
• Pain worse with increased velocity and duration
• Average age 14
• Average duration of symptoms 8 months

9
Little Leaguers Shoulder

• Diagnosis
• Tenderness over physis
• Pain with motion at extremes
• Possible discomfort with resistance testing

10
Little Leaguers Shoulder

• Radiology
• Widening of the proximal humeral physis
• Easily seen on bilateral AP internal and external
  rotation x-rays
• Associated findings
• Demineralization
• Sclerosis
• Fragmentation of lateral aspect of proximal
  humeral metaphysis

11
Radiographic findings

• Affected shoulder

• Normal shoulder

12
Little Leaguers Shoulder

• Treatment
• Rest until symptoms subside with pain-free ROM
• Gradual return to throwing when symptoms subside
  remodeling on x-ray can take several months
  longer
• PT usually not beneficial may have worse pain
  with strengthening exercises

13
Little Leaguers Shoulder

• Guidelines for return to throwing
• Full, painless ROM
• Full strength
• No apprehension or discomfort in the cocking
  phase of throwing

14
Little Leaguers Shoulder

• Carson Gasser, AJSM 1998
• Average patient age 14
• Average duration of symptoms 7.7 months
• 83 of patients were pitchers
• All 23 patients had widening of physis on x-ray
• All patients treated with rest for an average of
  3 months
• 91 returned to baseball and were asymptomatic

15
Little Leaguers Shoulder

• Conclusion