Little League Shoulder

Little League Shoulder (Proximal Humeral Epiphysiolysis) is an overuse injury affecting the proximal humeral growth plate in skeletally immature throwing athletes.

Pathophysiology:

• Essentially a Salter-Harris Type I stress fracture of the proximal humerus physis
• Occurs due to repetitive rotational shear and distraction forces
• The physis (growth plate) is the "weak link" in the kinetic chain of the young athlete
• The proximal humerus contributes 80% of longitudinal growth of the arm
• Rapid growth spurts increase susceptibility as the physis widens and weakens

Epidemiology:

• Age: 11-16 years (skeletally immature)
• Gender: Nearly exclusive to males
• Sport: Baseball pitchers (most common), tennis, volleyball, cricket
• Mechanism: Repetitive overhead throwing with high torque

Proximal Humerus Development:

• Ossification centers:
  • Head (appears 6 months)
  • Greater Tuberosity (appears 3 years)
  • Lesser Tuberosity (appears 5 years)
• Coalescence: Centers merge at age 5-7 to form single epiphysis
• Physeal Closure: Typically closes at age 14-17 (females earlier) or 16-19 (males)
• Contributes 80% of humeral length

Mechanics of Injury:

• Late Cocking Phase: Maximal external rotation places rotational shear stress across the physis.
• Deceleration Phase: Distraction forces pull the epiphysis.
• The physis is weaker against shear and tension than compression.
• Repetitive microtrauma leads to widening of the hypertrophic zone of the physis, failure of calcification, and eventual stress fracture.

Blood Supply Considerations:

• The proximal humeral epiphysis is supplied by the arcuate artery (ascending branch of the Anterior Humeral Circumflex Artery).
• The physis acts as a barrier to blood flow from the metaphysis.
• Although damage to the physis can theoretically disrupt supply, avascular necrosis (AVN) is extremely rare in Little League Shoulder because the fracture is usually Type I (slipped) without significant displacement or vessel disruption.

Adaptive Changes (Humeral Retrotorsion):

• Throwers normally develop increased humeral retroversion (bony adaptation).
• The proximal humerus "twists" during growth to allow the hand to reach further back in late cocking.
• This results in increased External Rotation (ER) and decreased Internal Rotation (IR).
• Total Arch of Motion (ER + IR) should remain equal to the contralateral side.
• This allows greater external rotation range without checking the capsule.
• In Little League Shoulder, "Opening Up Early" (anterior trunk rotation) causes the arm to lag behind, increasing the torque on the physis beyond its limits.
• Biomechanical analysis often reveals that the pitcher relies too much on the arm and not enough on the legs/trunk ("Arm Thrower").

History:

• Patient: Young male pitcher (11-16 years)
• Pain: Progressive onset shoulder pain
• Location: Proximal humerus / Lateral shoulder (Deep ache)
• Timing: Initially only with throwing, progresses to ADLs
• Volume: History of high pitch counts, recent increase in play, or "showcase" events
• Mechanics: Often reports fatigue or "dead arm" sensation

Physical Examination:

• Inspection: Usually normal. Mild atrophy in chronic cases.
• Palpation: Maximal tenderness over the proximal humeral physis. This is the hallmark. (Lateral aspect, just below acromion).
• ROM:
  • GIRD (Glenohumeral Internal Rotation Deficit) common
  • Increased External Rotation (adaptive)
• Strength: Often normal, but pain with resisted abduction/rotation.
• Special Tests:
  • Neer/Hawkins: Negative (or false positive due to extensive irritability)
  • O'Brien's: Usually negative
  • Scapular Dyskinesis: Check for winging/dysrhythmia (predisposing factor)

Plain Radiographs (Mandatory):

• Views: AP (Internal/External Rotation), Axillary Lateral.
• Must order COMPARISON VIEWS of the contralateral shoulder.

MRI:

• Usually not necessary if X-rays are diagnostic.
• Indicated if:
  • X-rays normal but high clinical suspicion (early stress reaction)
  • Unusual presentation (rule out tumor/infection)
  • Assessing healing/return to sport (sometimes)
• Findings:
  • Physeal edema (high T2 signal)
  • Metaphyseal edema usually extending into shaft
  • Periosteal edema

CT Scan:

• Rarely indicated. Avoid radiation in children.

Growth Arrest:

• The most feared complication.
• Continued throwing through pain leads to bar formation.
• Result: Shortened humerus or varus deformity.
• Usually humerus shortening is well tolerated functionally but cosmetically apparent.

For Standard Nonoperative Cases: (Refer to Management > Nonoperative Protocol)

If Surgery was performed (Acute Fraction Fixation):

• 0-4 Weeks: Sling immobilization. Pendulums only.
• 4 Weeks: Pin removal (if K-wires used). Start Active Assist ROM.
• 6-12 Weeks: Strengthening phases.
• Return to Sport: Delayed compared to stress fracture (often 6 months+).

Prognosis:

• Excellent with compliance.
• Almost all athletes return to previous level of play.
• Key determinant: Patient/Parent compliance with rest.

Long term:

• No association with adult osteoarthritis.
• Adaptation of humeral retroversion persists.

Counseling for Growth Arrest:

• Although rare (less than 1%), premature closure can occur if warnings are ignored.
• Resultant shortening is usually 1-2cm if near skeletal maturity.
• If young (e.g., 10-12 years), shortening can be significant (5cm+).

Epidemiology:

• Less common in Australia than USA due to lower baseball participation.
• Seen in Cricket (Bowlers) - although pars defects (spondylolysis) are more common in bowlers.
• Seen in Tennis: Particularly in players utilizing the "kick serve" which requires extreme external rotation and back arching, similar to the baseball pitch.
• Seen in Volleyball: Frequent in spikers and jump servers due to repetitive overhead loading.
• Emerging in "Academy" style baseball programs in Australia.

Cricket Fast Bowlers:

• While lumbar stress fractures (spondylolysis) are the classic injury in fast bowlers, proximal humeral stress pathology can occur.
• Mechanism: High rotational torque during the delivery stride.
• Differences: Cricket bowlers deliver with a straight arm. The distraction forces are higher, but the rotational torque might be different compared to the "late cocking" of baseball.
• Management principles remain identical: Bowling workload management (e.g., Cricket Australia guidelines).

Prevention Strategies:

• Adherence to Cricket Australia / Baseball Australia pitch/over count guidelines.
• Mandatory rest periods (3 months off per year).
• Avoidance of "showcase" events where intensity is effectively 100% without buildup.

Management:

• Managed by Sports Physicians or Orthopaedic surgeons.
• Physiotherapy led rehabilitation.
• Standard consultation reimbursements apply. There are no specific procedural codes for rest management.