Vascular implications of minimally invasive plating of proximal humerus fractures

Objectives: Open reduction and internal fixation of proximal humerus fractures through the anterolateral acromial approach, which uses the anterior deltoid raphe and axillary nerve protection, has recently been advocated as a minimally invasive technique. Several recent reports have indicated variable and unpredictable vascular injuries to the humeral-head blood supply after a proximal humerus fracture, and thus a direct approach that minimizes further vascular compromise may be preferable. The purpose of this study was to define the relationship of this surgical interval to the lateral plating zone of the proximal humerus and to the penetrating vascular supply of the humeral bead. Design: Cadaveric vascular injection study. Setting: Cadaveric dissection laboratory. Patients: Six cadaveric specimens. Intervention: The anterolateral acromial approach was performed on six cadaveric upper-extremity specimens. A locking proximal humerus plate was applied to the lateral proximal humerus, and the axillary artery was cannulated proximal to the circumflex humeral arteries. Dyed latex polymer was injected and allowed to harden, and dissection was performed to visualize the vasculature of the proximal humerus. Plates were then removed and the specimens were further inspected to examine the blood supply. Main Outcome Measurements: The relationship of the anterolateral acromial approach to the lateral plating zone of the proximal humerus and the vascular supply of the humeral head. Results: In all specimens, the filling of the anterior and posterior vessels that supplied the humeral head were undisturbed after use of the anterolateral acromial approach and locked plating. The blood vessels to the head-penetrating vascular branches were not in the surgical field. A bare spot on the lateral proximal humerus existed in the region of the greater tuberosity, which was 30 mm wide and between two penetrating humeral-head epiphyseal vessels. The nearest penetrating vessels were close to the plate, 4 mm anterior and 7 mm posterior. The anterior humeral circumflex vessel and its ascending branch, which provides critical blood supply to the humeral head, coursed directly in the region of the deltopectoral approach. Conclusions: Minimally invasive techniques have many potential benefits for fracture healing, but new surgical approaches often must be used to take full advantage of these newer methods. Splitting the anterior deltoid raphe from the acromion distally allowed direct access to the lateral plating zone of the proximal humerus. The bare spot in this region may be a safe area for plate application, if the plate is placed appropriately with thorough knowledge of the vascular anatomy. These findings may be of particular importance if the vascular supply to the humeral head has already been partially compromised by preceding trauma. This direct approach to the lateral bare spot on the proximal humerus may minimize iatrogenic vascular injury when treating these fractures.