title: Effects of sex differences on scapular motion during arm elevation.
abstract: BACKGROUND
  Scapular motion during arm elevation is frequently evaluated in patients with shoulder disorders because it provides clinically useful information. With the development of measurement devices and improvement in accuracy, comparisons under various conditions have recently been reported. However, in most of these reports, the subjects examined were limited to males, or a mixed population of males and females. Only a few reports have described sex differences. In the current study, we performed three-dimensional dynamic analysis of arm elevation and investigated whether there is a sex difference in scapular motion.
  
  
  METHODS
  Subjects included 18 healthy adult males (18 shoulders) and 19 healthy adult females (19 shoulders). Thirty-seven shoulders were on the dominant side. The age range was 20.5 ± 0.03 years. Subjects performed scapular plane arm elevation, and kinematic data were recorded using an electromagnetic tracking device. Scapular upward rotation and internal rotation angles and the posterior tilt angle accompanying arm elevation were calculated from recorded data. Changes in each angle during scapular motion were recorded according to sex.
  
  
  RESULTS
  There were sex differences in scapular upward rotation and internal rotation angles. The upward rotation angle was significantly greater in males, whereas the internal rotation angle was significantly greater in females. No sex differences were noted in the scapular posterior tilt angle.
  
  
  CONCLUSIONS
  Findings of this study may serve as basic data for scapular motion during scapular plane elevation in healthy males and females. In addition, it is necessary to evaluate and treat the shoulder while taking sex differences in scapular movement into consideration.
authors.affiliation: Department of Physical Therapy, Fukuoka Rehabilitation College 3-29-17 Hakataekimae Hakata-ku, Fukuoka-si, Fukuoka Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Nagamatsu
authors.affiliation: Faculty of Health Science, Kyoto Tachibana University 34 Yamada-cho Oyake Yamashina-ku Kyoto-si, Kyoto Japan.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Kai
authors.affiliation: Department of Orthopedic Surgery, Kurume University Medical Center 155-1 Kokubu-machi Kurume-si, Fukuoka Japan.
authors.forename: Masafumi
authors.initials: M
authors.lastname: Gotoh
authors.affiliation: Kurume University School of Medicine Graduate School 67 Asahi-machi Kurume-si, Fukuoka Japan.
authors.forename: Kazuya
authors.initials: K
authors.lastname: Madokoro
authors.affiliation: Department of Orthopedic Surgery, Kurume University 67 Asahi-machi Kurume-si, Fukuoka Japan.
authors.forename: Naoto
authors.initials: N
authors.lastname: Shiba
keywords: Dynamic analysis; Electromagnetic tracking device; Kinematics; Scapula; Sex differences