Safe Zones for Cerclage Wiring of the Humeral Diaphysis

Cerclage wiring of the humeral diaphysis entails particular danger to the radial nerve and the deep brachial artery. We sought to delineate safe zones for minimally invasive cerclage wiring of the humeral diaphysis, specifically in relation to the radial nerve and accompanying vasculature. Cerclage wires were percutaneously inserted into three groups of fresh-frozen cadaveric humeri. Group 1-proximal midshaft humerus at 30% of humeral height (n = 4); Group 2-midshaft spiral groove at 45% of humeral height (n = 4); and Group 3-distal midshaft humerus at 60% of humeral height (n = 4). Subsequently, an extensive surgical exploration of the arteries and nerves around the humerus was performed, noting any disturbance to the vessels or nerves and measuring the distance from the cerclage wire to the radial nerve. Neurovascular structures were injured in 75% of specimens when the cerclage wire was inserted at the level of the spiral groove. Both posterior structures, e.g. the radial nerve and the deep brachial artery, and medial structures, e.g., the median nerve and brachial artery, were incarcerated. Application of the cerclage at 30% or 60% of humeral height did not cause neurovascular injury. Minimally invasive application of the cerclage wire at the spiral groove, which is at 45% of humeral height, is likely to cause injury to neurovascular structures. Application of the cerclage at the proximal or distal midshaft humeral areas is associated with less risk of such injury. Clin. Anat. 33:552-557, 2020. © 2019 Wiley Periodicals, Inc.