title: Quantitative assessment of the vascularity of the proximal part of the humerus.
abstract: BACKGROUND
  The current consensus in the literature is that the anterolateral branch of the anterior humeral circumflex artery provides the main blood supply to the humeral head. While the artery is disrupted in association with 80% of proximal humeral fractures, resultant osteonecrosis is infrequent. This inconsistency suggests a greater role for the posterior humeral circumflex artery than has been previously described. We hypothesized that the posterior humeral circumflex artery provides a greater percentage of perfusion to the humeral head than the anterior humeral circumflex artery does.
  
  
  METHODS
  In twenty-four fresh-frozen cadaver shoulders (twelve matched pairs), we cannulated the axillary artery proximal to the thoracoacromial branch and ligated the brachial artery in the forearm. In each pair, one shoulder served as a control with intact vasculature and, in the contralateral shoulder, either the anterior humeral circumflex artery or the posterior humeral circumflex artery was ligated. Gadolinium was injected through the cannulated axillary arteries, and magnetic resonance imaging was performed. After imaging, a urethane polymer was injected, and specimens were dissected. For volumetric analysis, the gadolinium uptake on the magnetic resonance imaging was quantified in each quadrant of the humeral head with use of a custom automated program. The gadolinium uptake was compared between the control and ligated sides and between the ligated anterior humeral circumflex artery and ligated posterior humeral circumflex artery groups.
  
  
  RESULTS
  The posterior humeral circumflex artery provided 64% of the blood supply to the humeral head overall, whereas the anterior humeral circumflex artery supplied 36%. The posterior humeral circumflex artery also provided significantly more of the blood supply in three of the four quadrants of the humeral head.
  
  
  CONCLUSIONS
  The finding that the posterior humeral circumflex artery provides 64% of the blood supply to the humeral head provides a possible explanation for the relatively low rates of osteonecrosis seen in association with displaced fractures of the proximal part of the humerus. In addition, protecting the posterior humeral circumflex artery during the surgical approach and fracture fixation may minimize loss of the blood supply to the humeral head.
authors.affiliation: Hospital for Special Surgery, 535 East 70th Street, New York, NY 10021, USA. hettrichc@hss.edu
authors.forename: Carolyn M
authors.initials: CM
authors.lastname: Hettrich
authors.forename: Sreevathsa
authors.initials: S
authors.lastname: Boraiah
authors.forename: Jonathan P
authors.initials: JP
authors.lastname: Dyke
authors.forename: Andrew
authors.initials: A
authors.lastname: Neviaser
authors.forename: David L
authors.initials: DL
authors.lastname: Helfet
authors.forename: Dean G
authors.initials: DG
authors.lastname: Lorich
mesh_terms: D000368:Aged; D001158:Arteries / Q000033:anatomy & histology; D001366:Axillary Artery / Q000033:anatomy & histology; D002102:Cadaver; D003287:Contrast Media; D019786:Gadolinium DTPA; D006801:Humans; D006811:Humerus / Q000098:blood supply*; D066298:In Vitro Techniques; D018810:Magnetic Resonance Angiography; D008875:Middle Aged; D011108:Polymers
chemical_list: D003287:Contrast Media; D011108:Polymers; D019786:Gadolinium DTPA