Courtesy: Prof Nabil Ebraheim
ANATOMY OF BLOOD SUPPLY
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The blood supply to the proximal humerus is derived primarily from branches of the axillary artery.
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The most important contributor is the anterior humeral circumflex artery.
Anterior Humeral Circumflex Artery
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Arises from the axillary artery.
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Forms an anastomosis with the posterior humeral circumflex artery.
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Gives rise to an important ascending branch.
Ascending Branch
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Runs a few millimeters posterolateral and parallel to the long head of the biceps tendon.
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Courses along the bicipital groove.
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Penetrates the bone near the anatomical neck.
Arcuate Artery
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The terminal branch of the ascending branch of the anterior humeral circumflex artery.
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Enters the humeral head beneath the articular surface.
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Provides the majority of the blood supply to the humeral head.
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Functions as an end artery, with limited collateral circulation.
CLINICAL SIGNIFICANCE IN FRACTURES
Types of Proximal Humerus Neck Fractures
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Anatomical neck fractures
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Surgical neck fractures
Anatomical Neck Fractures
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Equivalent to fractures of the articular segment of the humeral head.
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Often disrupt the ascending branch and the arcuate artery.
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This interruption can lead to avascular necrosis of the humeral head.
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High risk of compromised vascularity.
Surgical Neck Fractures
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Occur distal to the humeral head blood supply.
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Blood supply to the humeral head is usually preserved.
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Associated with a lower incidence of avascular necrosis compared to anatomical neck fractures.
FACTORS INFLUENCING AVASCULAR NECROSIS
The risk of avascular necrosis following proximal humerus fractures is influenced by:
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Degree of fracture comminution
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Disruption of soft tissue attachments
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Extent of surgical dissection
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Method and accuracy of fracture reduction
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Position and type of fixation implant
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Preservation or damage to the medial hinge
KEY POINTS
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The arcuate artery is the critical vessel supplying the humeral head.
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Anatomical neck fractures pose the greatest risk for vascular compromise.
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Surgical technique plays a major role in preserving humeral head viability.
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Careful handling of soft tissues is essential during fracture fixation.
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