![]() ![]() With anterolateral plating, the axillary nerve is most frequently in danger when placing screws near the surgical neck through the middle segment of the plate. Care should be taken with incisions greater than 5 cm in length distal to the acromion. It is about 4.5 to 7 cm from the proximal humerus and 0.5 to 4 cm from the surgical neck, 15 traveling through the quadrilateral space with the posterior humeral circumflex artery. 14 During surgery, the axillary nerve can be difficult to identify, particularly in scarred shoulders. These are most commonly traction injuries that fully recover. The most commonly injured nerves in descending order are the axillary, suprascapular, radial, musculocutaneous, median, and ulnar nerves. Some degree of electromyographically detectable axonal loss occurs in 67% of patients with low energy proximal humerus fractures. The posterior humeral circumflex artery travels with the axillary nerve. The arcuate artery is a branch of the anterior humeral circumflex artery and ascends along the intertubercular groove before entering the humeral head. 13Īnteroposterior view of the shoulder illustrating the vascular supply to the proximal humerus. More than 90% of the reported cases occur in patients 50 years and older, possibly due to the loss of elasticity secondary to atherosclerosis. 12 Gross axillary artery injury is exceedingly rare however, in cases of significant shoulder trauma with a loss of Doppler signals and an enlarging axillary mass, vascular surgery should be consulted and a computed tomography angiogram ordered. 6, 11 Fractures with short calcar fragments (<8 mm), a disrupted medial hinge, and anatomic neck involvement are most prone to ischemia. The arcuate artery is the terminal, ascending branch of the anterior humeral circumflex artery and enters the humeral head near the anatomic neck. The proximal humeral blood supply is from the anterior and posterior humeral circumflex branches of the axillary artery, which are closely associated with the surgical neck and medial calcar ( Figure 2). GT denotes greater tuberosity LT, lesser tuberosity. 6Īnteroposterior view of the shoulder demonstrating tendinous attachments to the proximal humerus and the associated direction of fragment displacement. The pectoralis major inserts into the medial humeral shaft and deforms medially, while the deltoid inserts into the lateral humerus and deforms laterally ( Figure 1). The subscapularis inserts on the lesser tuberosity and produces medial deformity. The supraspinatus and teres minor insert on the greater tuberosity and produce a posterosuperior deformity. Tendons produce reliable deforming forces on bone fragments. Humeral shortening greater than 1 cm can impair deltoid function, whereas humeral lengthening and retroversion can impair tuberosity healing. 9 The pectoralis major tendon inserts 5 to 6 cm from the top of the humeral head, which is a reliable tool for estimating prosthetic stem length in severe fractures without landmarks. Most humeral heads have a diameter between 4 and 5 cm, and the head is slightly offset medially and posteriorly in relation to the humeral shaft. The glenohumeral joint is stabilized by the articular cartilage, labrum, ligaments, rotator cuff, and deltoid. ![]()
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