title: Ultrasound imaging of the humeral capitellum: a cadaveric study.
abstract: BACKGROUND
  Ultrasound is suitable for routine examinations of capitellar osteochondritis dissecans because it can visualize both the subchondral bone and the overlying articular cartilage non-invasively. The radial head interferes with the sonographically visible area of the articular surface of the humeral capitellum, although the precise extent of this is currently unknown. This study aimed to investigate the visible area of the humeral capitellum using both anterior and posterior ultrasonographic scans.
  
  
  METHODS
  Twelve elbows were used from cadavers with a mean age of 85.6 years. After marking a 45° angle in the anterior capitellum in a caudal direction using a drill, anterior and posterior, long-axis ultrasonographic scans were performed with the cadaveric elbows bent. The elbow-flexion angle at which the 45° point was obscured by the radial head was measured and these ultrasonic measurements were then verified by macroscopic observation.
  
  
  RESULTS
  The elbow-flexion angle at which the 45° point was obscured by the radial head was 24° in anterior scans and 102° in posterior scans. These ultrasonic measurements corresponded to the macroscopic measurements. The results showed that anterior, long-axis ultrasound scans could visualize the capitellum from 45° through the rest of the anterior area at 24° flexion of the elbow: the radial head obscured the area of the capitellum that is 21° anterior to the elbow flexion angle. Similarly, posterior long-axis scans could visualize the capitellum from 45° through the rest of the posterior area at 102° flexion of the elbow: the radial head obscured the area of the capitellum that is 57° posterior to the elbow flexion angle. The radial head obscured a 78° (21° + 57°) arc of the capitellum in ultrasonography.
  
  
  CONCLUSIONS
  This study thus clarified the area of the humeral capitellum visible in both anterior and posterior ultrasound scans in the sagittal plane.
authors.affiliation: Department of Orthopaedic Surgery, Nagoya City University Graduate School of Medical Science, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya, 467-8601, Japan, take10280425@yahoo.co.jp.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Takenaga
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Goto
authors.forename: Masahiro
authors.initials: M
authors.lastname: Nozaki
authors.forename: Masahito
authors.initials: M
authors.lastname: Yoshida
authors.forename: Takeshi
authors.initials: T
authors.lastname: Nishiyama
authors.forename: Takanobu
authors.initials: T
authors.lastname: Otsuka
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002102:Cadaver; D002358:Cartilage, Articular / Q000000981:diagnostic imaging*; D004551:Elbow Joint / Q000000981:diagnostic imaging / Q000503:physiopathology; D005260:Female; D006801:Humans; D006811:Humerus / Q000000981:diagnostic imaging*; D008297:Male; D010008:Osteochondritis Dissecans / Q000000981:diagnostic imaging* / Q000503:physiopathology; D016059:Range of Motion, Articular; D015203:Reproducibility of Results; D014463:Ultrasonography