title: Anterior translation and morphologic changes of the ulnar nerve at the elbow in adolescent baseball players.
abstract: The effect of repetitive throwing on the ulnar nerve is not clear. There are no published imaging studies regarding this issue in adolescent baseball players. The purpose of this cross-sectional ultrasonographic study was to use 5- to 10-MHz frequency ultrasonography to define the anterior translation and flattening of the ulnar nerve in different elbow positions. We divided 39 adolescent baseball players into two groups, 19 pitchers and 20 fielders, according to the amount of throwing. Twenty-four non-athlete junior high school students were also included as controls. We ultrasonographically examined each participant's ulnar nerve in the cubital tunnel with the elbow extended and at 45°, 90° and 120° of flexion. Anterior translation and flattening of the ulnar nerve occurred in all groups. Pitchers had larger-scale anterior translation than did controls. In pitchers, the ulnar nerve exhibited more anterior movement on the dominant side than on the non-dominant side. The anterior subluxation of the ulnar nerve occurred in players without ulnar nerve palsy and was not correlated with elbow pain. In addition to the known musculoskeletal adaptations of pitchers' elbows, ultrasonography revealed new changes in the ulnar nerve, anterior translation and subluxation, after repetitive throwing. These changes might also be physiologic adaptations of throwing elbows.
authors.affiliation: Department of Orthopaedics, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan; Department of Orthopaedics, Tainan Hospital Sinhua Branch, Tainan, Taiwan.
authors.forename: Ta-Wei
authors.initials: TW
authors.lastname: Tai
authors.forename: Li-Chieh
authors.initials: LC
authors.lastname: Kuo
authors.forename: Wen-Chau
authors.initials: WC
authors.lastname: Chen
authors.forename: Lin-Hwa
authors.initials: LH
authors.lastname: Wang
authors.forename: Shu-Yi
authors.initials: SY
authors.lastname: Chao
authors.forename: Christine Nai-Hui
authors.initials: CN
authors.lastname: Huang
authors.forename: I-Ming
authors.initials: IM
authors.lastname: Jou
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology; D000293:Adolescent; D018771:Arthralgia / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology*; D001484:Baseball / Q000293:injuries*; D004550:Elbow / Q000033:anatomy & histology / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D006801:Humans; D008297:Male; D009038:Motion; D009068:Movement; D014459:Ulnar Nerve / Q000033:anatomy & histology / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D014463:Ultrasonography
keywords: Adaptation; Adolescent; Baseball; Elbow; Ulnar nerve; Ultrasonography