title: Glenoid stress distribution in baseball players using computed tomography osteoabsorptiometry: a pilot study.
abstract: BACKGROUND
  It is important to understand the loading conditions when considering the pathology of shoulder disorders in overhead athletes. However, because throwing is a complicated motion and methods to directly determine stress distribution are complex, direct measurement of the stress distribution across the glenohumeral joint has not been attempted. Subchondral bone density reportedly reflects the cumulative stress acting on a joint surface under actual loading conditions.
  
  
  OBJECTIVE
  To assess alterations in stress distribution across the glenoid cavity caused by pitching, we investigated the distribution of subchondral bone density in nonathletic volunteers and asymptomatic baseball players, including fielders and pitchers.
  
  
  METHODS
  We collected CT imaging data from the dominant-side shoulder of 10 nonathletic volunteers (controls), 10 fielders, and 10 pitchers in a competitive college baseball league (all men aged 19–24 years, mean 20.7 years). We measured the distribution of subchondral bone density of the glenoid cavity using CT osteoabsorptiometry. The obtained stress distribution map was divided into four segments: anterosuperior, anteroinferior, posteroinferior, and posterosuperior regions. We quantitatively analyzed the location and percentages of high-density regions on the articular surface.
  
  
  RESULTS
  The percentages of high-density regions, including the anteroinferior and posterior segments, were greater in pitchers and fielders than in controls. The percentages of high-density regions did not differ between pitchers and fielders.
  
  
  CONCLUSIONS
  The bicentric density patterns indicated that the cumulative force of pitching activity affected the long-term stress distribution across the glenoid cavity.
  
  
  CONCLUSIONS
  Our data should be useful for analyzing pitching activity and clarifying the pathology of shoulder disorders associated with throwing.
authors.affiliation: Department of Orthopaedic Surgery, Hokkaido University School of Medicine, Kita 15 Nishi 5 Kita-ku Sapporo, Hokkaido 0608368, Japan.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Shimizu
authors.forename: Norimasa
authors.initials: N
authors.lastname: Iwasaki
authors.forename: Kinya
authors.initials: K
authors.lastname: Nishida
authors.forename: Akio
authors.initials: A
authors.lastname: Minami
authors.forename: Tadanao
authors.initials: T
authors.lastname: Funakoshi
mesh_terms: D015502:Absorptiometry, Photon; D000328:Adult; D001484:Baseball / Q000293:injuries*; D001696:Biomechanical Phenomena; D015519:Bone Density; D012090:Cumulative Trauma Disorders / Q000000981:diagnostic imaging / Q000503:physiopathology*; D061165:Glenoid Cavity / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006801:Humans; D008297:Male; D000070599:Shoulder Injuries; D012785:Shoulder Joint / Q000000981:diagnostic imaging / Q000502:physiology; D014057:Tomography, X-Ray Computed; D055815:Young Adult