title: Distal pectoralis major tears: sonographic characterization and potential diagnostic pitfalls.
abstract: OBJECTIVE
  Distinction between musculotendinous tears of the pectoralis major and distal tendon avulsions is important, as the latter typically requires surgical repair. The objective of this study was to characterize the sonographic appearances of surgically proven distal tendon avulsion tears of the pectoralis major.
  
  
  METHODS
  A retrospective search of the radiology database (2001-2011) revealed 22 cases of pectoralis major tears on sonography, of which 9 had surgical correlation. Sonograms were retrospectively characterized by 3 fellowship-trained musculoskeletal radiologists in consensus with respect to the location and size of the fluid collection and the presence of tendon or tendonlike tissue superficial to the biceps brachii tendon.
  
  
  RESULTS
  At surgery, complete distal tendon avulsions or tears of the sternal head of the pectoralis were present in all 9 cases: isolated in 6 and combined with clavicular head tears in 3. The location of the fluid collection was at the musculotendinous junction in 89% (8 of 9) and medial to the biceps brachii tendon in 11% (1 of 9), with a mean largest dimension of 3.8 cm (range, 0.7-6.2 cm). In no case was fluid seen at the humeral attachment of the pectoralis. In 67% (6 of 9), linear thickened hypoechoic tissue was seen superficial to the biceps brachii tendon, which simulated an abnormal but intact tendon, whereas in 33% (3 of 9), a normal distal pectoralis tendon was seen.
  
  
  CONCLUSIONS
  Surgically proven distal pectoralis major tendon avulsions most commonly showed fluid collections at the musculotendinous junction and not at the humeral shaft, with either a normal tendon or hypoechoic tendonlike tissue over the biceps brachii long-head tendon. These findings may potentially cause misdiagnosis of distal tendon avulsions or tears as musculotendinous injuries.
authors.affiliation: Department of Radiology, University of Michigan Medical Center, 1500 East Medical Center Dr, TC2910L, SPC 5326, Ann Arbor, MI 48109 USA. jjacobsn@umich.edu.
authors.forename: Sun Joo
authors.initials: SJ
authors.lastname: Lee
authors.forename: Jon A
authors.initials: JA
authors.lastname: Jacobson
authors.forename: Sung-Moon
authors.initials: SM
authors.lastname: Kim
authors.forename: David
authors.initials: D
authors.lastname: Fessell
authors.forename: Yebin
authors.initials: Y
authors.lastname: Jiang
authors.forename: Gandikota
authors.initials: G
authors.lastname: Girish
authors.forename: Olaf
authors.initials: O
authors.lastname: Magerkurth
mesh_terms: D003951:Diagnostic Errors / Q000517:prevention & control*; D005260:Female; D006801:Humans; D022125:Lacerations / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D010369:Pectoralis Muscles / Q000000981:diagnostic imaging* / Q000293:injuries*; D015203:Reproducibility of Results; D012421:Rupture / Q000000981:diagnostic imaging; D012680:Sensitivity and Specificity; D013898:Thoracic Injuries / Q000000981:diagnostic imaging*; D014463:Ultrasonography / Q000379:methods*; D055815:Young Adult
keywords: injury; magnetic resonance imaging; pectoralis; sonography