The Shoulder in Youth Baseball Koco Eaton, M.D.

Little Leaguer’s 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

Little Leaguer’s 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

Little Leaguer’s 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

Little Leaguer’s 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

Little Leaguer’s 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

Little Leaguer’s Shoulder Risk Factors  Position played (pitcher, catcher, outfield, 3 rd 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

Little Leaguer’s 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

Little Leaguer’s Shoulder Diagnosis  Tenderness over physis  Pain with motion at extremes  Possible discomfort with resistance testing

Little Leaguer’s 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

Radiographic findings Affected shoulder Normal shoulder

Little Leaguer’s 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

Little Leaguer’s Shoulder Guidelines for return to throwing  Full, painless ROM  Full strength  No apprehension or discomfort in the cocking phase of throwing

Little Leaguer’s 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

Little Leaguer’s Shoulder Conclusion