Incidence and Characteristics of Elbow Injury in Japanese Youth Baseball Players: Comparison Between 2011 and 2021

Abstract

Background: Little League elbow, including humeral epicondylitis and osteochondritis dissecans, is a severe throwing injury in school-aged pitchers. Recent rule revisions have been implemented, and thus, prevention awareness may have increased.

Purpose: To compare the incidence of elbow injury in 2011 from a previous study with that in 2021 and examine changes in the incidence and characteristics of players with elbow injuries.

Study design: Cross-sectional study; Level of evidence, 3.

Methods: A survey based on the 2011 survey was conducted from September 1 to December 31, 2021, among 4060 third- to sixth-grade Little League players belonging to 203 teams in Kyoto, Japan. This survey included a 23-item checklist on physical condition and injury. The participants were classified into 2 groups according to the presence or absence of an elbow injury in the dominant arm during the season. The Wilcoxon rank-sum test was conducted to compare differences in basic information between the 2 groups. We also compared the differences in the 23 checklist items between the 2 groups using the chi-square or Fisher exact probability test.

Results: Overall, 98 teams (1335 players; age range, 8-12 years) returned the questionnaires (collection rate, 32.9%). The final analysis population (excluding incomplete questionnaires) was 678 (mean age, 10.6 ± 1.1 years). Elbow injuries accounted for 30.7% of all injury sites in the players. Overall, 61 players (9.0%) reported elbow injuries in 2021 compared with 19.1% of the players in the 2011 survey (P < .01) A significantly higher percentage of players with elbow injuries had elbow pain in extension (item 2 on the survey checklist, P < .001) and flexion (item 4, P < .0024), were regular players (item 5, P = .0288), played baseball under fatigue (item 8, P = .0028), and had lower and upper limb inflexibility (item 17, P = .0379; item 18, P = .0146; and item 22, P = .0085).

Conclusion: Study findings indicated that the incidence of elbow injuries has decreased significantly over the past 10 years, although the elbow joint still accounted for almost one-third of all injuries in Japanese youth baseball players.

Keywords: Little League elbow; pain; shoulder flexibility; throwing injury.

Figure 1.

(A) Percentage of players with injury according to area of the body. (B) Percent of players with elbow injury among players with pain in some part of the body..