The ulnar collateral ligament loading paradox between in-vitro and in-vivo studies on baseball pitching: (narrative review)

Bart Van Trigt*, Liset Vliegen, Ton Leenen, Dirk Jan Veeger

*Corresponding author for this work

Research output: Contribution to JournalReview articleAcademicpeer-review


Ulnar collateral ligament (UCL) weakening or tears occur in 16% of professional baseball pitchers. To prevent players from sustaining a UCL injury, it is important to understand the relationship between the UCL properties and elbow stabilizers with the load on the UCL during pitching. In-vitro studies showed that the ultimate external valgus torque of 34 Nm would rupture the UCL, which is in apparent conflict with the reported peak valgus torques in pitching (40–120 Nm). Assuming both observations are correct, the question rises why ‘only’ 16 out of 100 professional pitchers sustain a UCL rupture. Underestimation of the effect of other structures in in-vivo studies is most likely the explanation of this mismatch because the calculated in-vivo torque also includes possible contributions of functional and structural stabilizers. In-vitro studies show that the flexor-pronator mass has the potential to counteract valgus torque directly, whereas the elbow flexor-extensor muscles combined with the humeroradial joint might have an indirect effect on valgus torque by increasing the joint compression force. Accurate experimental electromyography data and a more detailed (musculoskeletal)mechanical model of the elbow are needed to investigate if and to what extent the structural and functional stabilizers can shield the UCL during pitching.

Original languageEnglish
Pages (from-to)19-29
Number of pages11
JournalInternational Biomechanics
Issue number1
Early online date28 Apr 2021
Publication statusPublished - 2021

Bibliographical note

Funding Information:
This work was supported by the NWO Domain Applied and Engineering Sciences (AES) under project number [R/003635]. This NWO-funded project, called Breaking the High Load?Bad Coordination Multiplier in Overhead Sports Injuries part of the Citius Altius Sanius perspective program (Project 7), is a cooperative effort between the Royal Dutch Baseball and Softball Federation, Royal Dutch Tennis Federation, Vrije Universiteit Amsterdam, Delft University of Technology, Mil? Fysiotherapy, PitchPerfect and PLUX. We would like to thank Dr. Michel van den Bekerom for proofreading the paper and Eva Galjee for helping with the figures.

Publisher Copyright:
© 2021 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.

Copyright 2021 Elsevier B.V., All rights reserved.


  • elbow injury
  • electromyography; Tommy John Surgery;
  • musculoskeletal modelling
  • overhead sports
  • UCL


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