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Medial epicondyle apophysitis
Other Resources UpToDate PubMed

Medial epicondyle apophysitis

Contributors: Brianna Caraet MD, Surya Mundluru MD
Other Resources UpToDate PubMed


Causes / typical injury mechanism: The mechanism that predisposes the pediatric population to this injury involves repeated valgus stress to the elbow during pitching. This repetitive trauma causes tensile overload on the medial epicondyle and compressive force on the lateral epicondyle during cocking and acceleration.

Classic history and presentation: Little League elbow is a common injury, predominantly seen in skeletally immature baseball players. It is also seen with other overhead athletic activities. The pathology can present as medial epicondyle apophysitis in younger children (less than 12 years), and in extreme cases as a medial epicondyle avulsion fracture in older children (aged 12-14 years).

Growth cartilage is vulnerable during childhood, as it is less resistant to stress than the articular cartilage present in skeletally mature patients. In addition to medial epicondyle injury, capitellum osteochondritis dissecans, flexor-pronator muscle mass injury, and ulnar collateral ligament (UCL) injury may be seen.

  • Little League elbow occurs most commonly in the pediatric population, as the medial epicondyle is the weakest structure in the medial elbow in the skeletally immature.
  • Age – Incidence among this group is 20%-40%.
Risk factors:
  • The primary risk factor for skeletally immature patients is overuse with unregulated pitch volume. In one study, when pitchers aged 9-12 years threw more than 75 pitches in a game, there was a 35% increase in elbow pain. When they exceeded 600 pitches in a season, there was a significant increase in elbow pain.
  • Poor pitching / throwing mechanics and physical conditioning.
  • Throwing despite arm fatigue.


M77.00 – Medial epicondylitis, unspecified elbow

3951000119103 – Medial epicondyle apophysitis due to overuse

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Diagnostic Pearls

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Differential Diagnosis & Pitfalls

Medial elbow pain:
Since repetitive valgus overload creates a compressive force on the lateral side, evaluate for lateral side injuries as well:

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Last Reviewed:04/01/2022
Last Updated:04/04/2022
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Medial epicondyle apophysitis
Copyright © 2023 VisualDx®. All rights reserved.