Intraoperative Radiographic Method of Locating the Radial Head Safe Zone: The Bicipital Tuberosity View

HYPOTHESIS The proximal radius is asymmetrical, is mostly articular, and rotates through a large arc of motion. Because of these anatomic factors, there is limited space for hardware. This is magnified in the setting of complex fractures. The portion of the radial head where a radial head plate can be placed without compromising forearm motion has been termed the "safe zone." We hypothesized that the bicipital tuberosity could be used as a reproducible intraoperative fluoroscopic landmark to confirm radial head plate position in the safe zone. METHODS Seventeen cadaveric radii were evaluated. First, the anatomic safe zone was identified using the method previously described by Caputo et al. A proximal radial plate was then placed in the center of this safe zone. The relationship of the plate to the tuberosity was evaluated, and the angle from the point of the greatest tuberosity profile to the center of the safe zone was measured. RESULTS The maximum profile of the bicipital tuberosity is 166° ± 10° from the center of the safe zone as described by Caputo et al. By use of radiographic imaging, a radial head plate placed directly opposite the bicipital tuberosity will be within the safe zone. This position can be ascertained fluoroscopically with an anteroposterior view of the proximal forearm, in which the surgeon rotates the forearm into full supination. The plate should be placed opposite the bicipital tuberosity as seen on the greatest profile at maximum supination. With this method, the plate will be consistently placed within the safe zone. CONCLUSION The bicipital tuberosity can be used as a consistent radiographic anatomic landmark to ensure proximal radial plate placement within the safe zone. If the proximal radial head plate is placed 166° ± 10° opposite the bicipital tuberosity, a landmark easily identified on intraoperative imaging, the implant will be in the safe zone and will not impinge on the ulna in rotation.