Impact of changes in pitch limit guidelines on position distribution and capitellar OCD in youth baseball: A 6-year cohort study

Rikuto Yoshimizu; Junsuke Nakase; Yasushi Takata; Naoki Takemoto; Manase Nishimura; Kentaro Fujita; Satoru Demura

doi:10.1016/j.jsams.2026.04.007

Impact of changes in pitch limit guidelines on position distribution and capitellar OCD in youth baseball: A 6-year cohort study

J Sci Med Sport. 2026 Apr 20:S1440-2440(26)00146-5. doi: 10.1016/j.jsams.2026.04.007. Online ahead of print.

Authors

Rikuto Yoshimizu¹, Junsuke Nakase², Yasushi Takata², Naoki Takemoto², Manase Nishimura², Kentaro Fujita², Satoru Demura²

Affiliations

¹ Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kanazawa University, Japan; Fukui General Hospital, Japan. Electronic address: cogito_ergo_sum_1010@yahoo.co.jp.
² Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kanazawa University, Japan.

PMID: 42062171
DOI: 10.1016/j.jsams.2026.04.007

Abstract

Objectives: To evaluate changes in position distribution and capitellar osteochondritis dissecans detected at annual screening before and after the 2019 introduction of pitch limit guidelines, focusing on dual-role players.

Design: Retrospective observational study using an interrupted time series design.

Methods: Annual ultrasonography screening was performed from 2017 to 2023 in 1576 players aged 10-12 years. Players were classified as pitcher, catcher, or dual-role. Position distribution was analyzed using interrupted time series binomial models; chi-square tests were used for supplementary comparisons. Osteochondritis dissecans was analyzed using interrupted time series Poisson regression with an offset for the annual number screened and 95% confidence intervals. Worst-case sensitivity analyses assumed all missing confirmatory examinations were osteochondritis dissecans; analyses were repeated in males only.

Results: Catcher proportion decreased from 21.2% to 15.6% in a supplementary pre-post comparison (p = 0.011). Dual-role players accounted for 18.1% pre-guideline and 22.3% post-guideline and increased from 17.4% in 2017 to 26.1% in 2023 (p = 0.040). Overall osteochondritis dissecans was 3.6% pre-guideline and 1.8% post-guideline (p = 0.055); among dual-role players, 6.7% and 1.9% (p = 0.083). In Poisson interrupted time series using confirmed cases only, no significant level change was detected (incidence rate ratio 0.53, 95% confidence interval 0.09-3.00). Under the worst-case assumption, guideline introduction was associated with an immediate decrease in overall osteochondritis dissecans (incidence rate ratio 0.15, 95% confidence interval 0.035-0.64). Findings were consistent in males only.

Conclusions: Guideline introduction coincided with fewer catchers and more dual-role players, while osteochondritis dissecans detected at annual screening did not show evidence of an increase among dual-role players.

Keywords: Baseball; Capitellar OCD; Dual-role player; Osteochondritis dissecans; Pitch count limit.