title: The superomedial bare area of the costal scapula surface: a possible cause of snapping scapula syndrome.
abstract: OBJECTIVE
  Scapulothoracic bursitis is a painful condition of the scapulothoracic articulation, which may be caused by various pathological anatomical associations. We have arthroscopically observed a constant bare area of bone on the costal scapula surface in patients with scapulothoracic bursitis, contradictory to traditional anatomical reports of scapular muscle relations. We undertook a cadaveric study to further define this anatomical feature.
  
  
  METHODS
  Twelve cadaveric shoulders were dissected. The costal surface of the scapula was systematically examined for the presence of a superomedial bare area in each shoulder by three independent clinicians, with dimensions measured using digital calipers.
  
  
  RESULTS
  In all shoulders, there was a clearly defined bare area of bone on the superomedial aspect of the costal surface of the scapula between the serratus anterior insertion and subscapularis origin. The bare area was typically crescenteric in shape, with variable length (mean 22.3 ± 6.0 mm) and width (10.8 ± 2.8 mm). The bare area length (p = 0.043) and width (p = 0.033) were significantly greater in female shoulders compared to male shoulders.
  
  
  CONCLUSIONS
  We have established the presence of the superomedial bare area of the costal scapula surface. With an absence of overlying subscapularis muscle, this bare area carries the potential for scapulothoracic impingement, and should be considered as a possible aetiological factor in all patients presenting with scapulothoracic bursitis.
authors.affiliation: Department of Orthopaedic Surgery, Auckland City Hospital, Private Bag 92024, Auckland Mail Centre, Auckland, 1142, New Zealand. drmattboyle@hotmail.com
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Boyle
authors.forename: Peter
authors.initials: P
authors.lastname: Misur
authors.forename: Seung-Min
authors.initials: SM
authors.lastname: Youn
authors.forename: Craig M
authors.initials: CM
authors.lastname: Ball
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001837:Body Weights and Measures / Q000379:methods*; D002062:Bursitis / Q000150:complications; D002102:Cadaver; D005260:Female; D006801:Humans; D007592:Joint Diseases / Q000209:etiology / Q000473:pathology; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D012540:Scapula / Q000033:anatomy & histology*; D012737:Sex Factors; D012785:Shoulder Joint / Q000033:anatomy & histology; D013577:Syndrome