Characteristics of subscapularis muscle strain in professional baseball players: A case series

Background: Subscapularis muscle strains can develop in professional baseball players, rendering the players unable to continue playing for a certain period. However, the characteristics of this injury are not well known. The purpose of the present study was to investigate the details of the injury and the post injury course of subscapularis muscle strain in professional baseball players. Methods Of 191 players (83 fielders and 108 pitchers) who were members of a single Japanese professional baseball team between January 2013 and August 2022, 8 players (4.2%) had subscapularis muscle strain and were enrolled in this study. The diagnosis of muscle strain was made on the basis of shoulder pain and magnetic resonance imaging findings. The incidence of subscapularis muscle strain, the details of the site of the injury, and the time to return to play were examined. Results Subscapularis muscle strain occurred in 3 (3.6%) of 83 fielders and 5 (4.6%) of 108 pitchers, with no significant difference between fielders and pitchers. All players had injuries on the dominant side. Most injuries were located at the myotendinous junction and in the inferior half of the subscapularis muscle. The mean time to return to play was 55.3 ± 40.0 (range, 7-120) days. At a mean 21.0 months after the injury, there were no re-injured players. Conclusions Baseball players who have shoulder pain should be regarded as having possible subscapularis muscle strain, and proactive examination should be considered. Trial registrations: Not applicable