Quantitative Assessment of the Vascularity of the Proximal Part of the Humerus

Carolyn M. Hettrich, MD, MPH¹, Sreevathsa Boraiah, MD¹, Jonathan P. Dyke, PhD², Andrew Neviaser, MD¹, David L. Helfet, MD¹ and Dean G. Lorich, MD¹

¹ Hospital for Special Surgery, 535 East 70th Street, New York, NY 10021.
² Weill Medical College of Cornell University, 1300 York Avenue, New York, NY 10021

Investigation performed at the Hospital for Special Surgery, New York, and Weill Medical College of Cornell University, New York, NY

Disclosure In support of their research for or preparation of this work, one or more of the authors received, in any one year, outside funding or grants in excess of $10,000 from Synthes. Neither they nor a member of their immediate families received payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity.

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.

Clinical Relevance Understanding the contributions to the blood flow to the humeral head can better aid in surgical planning and fracture fixation.