Arterial supply of the tendinous rotator cuff insertions: an anatomical study.

Background: Confirming the presence of arteries crossing the osteotendinous junctions (OTJs) of the rotator cuff may explain why rates of avascular necrosis (AVN) of the humeral head vary between three- and four-part proximal humeral fractures. It is hypothesized that the humeral head remains better vascularized in three-part fractures because one tuberosity with its inserting rotator cuff tendons is still attached to the articular fragment and supplying it with blood.

Methods: Eighty rotator cuff tendons from 20 shoulder girdles of cadavers aged 68-94 years were studied. In six shoulder girdles, the anterior circumflex humeral artery and posterior circumflex humeral artery (PCHA) were injected with ink, and the extra- and intraosseous courses of the vasculature were dissected until the OTJs of the rotator cuff.

Results: The rotator cuff insertions received an arterial supply across their OTJs in 50% of cases (75% in supraspinatus, 67% in subscapularis, 33% in infraspinatus and 20% in teres minor). Supraspinatus and subscapularis insertions were vascularized by the arcuate artery, while the insertions of infraspinatus and teres minor were supplied by an unnamed terminal branch of the PCHA. This was named 'posterolateral artery'.

Conclusion: The presence of arteries crossing the OTJs of the rotator cuff, as well as the differences in the frequency arteries crossed the OTJs of individual rotator cuff tendons, may help explain why there is a lower rate of AVN of the humeral head in thee-part, compared with four-part proximal humeral fractures.