The radial neck is the constricted segment of the proximal radius between the radial head and the radial tuberosity, approximately 10 mm long. The annular ligament encircles the radial neck, holding it against the ulnar radial notch and forming the proximal radioulnar joint. The neck angle relative to the shaft (neck-shaft angle, approximately 10-15 degrees) is critical in understanding radial head fractures and prosthetic replacement.
Radial neck fractures occur in children as the radius is more cartilaginous at this level, contrasting with adult radial head fractures. Significant radial neck angulation (greater than 30 degrees) or translation requires reduction in children. In Mason type IV and complex radial head fractures in adults, radial neck comminution often accompanies head fragmentation, requiring radial head replacement rather than fixation. The posterior interosseous nerve winds around the radial neck at the level of the radial head and is at significant risk during lateral elbow approaches that extend distally past the radiocapitellar joint.
In children, valgus stress at the elbow fractures the radial neck rather than the head due to its physis, producing angulation that requires closed reduction under anaesthesia or percutaneous leverage techniques when angulation exceeds 30 degrees or translation is more than 3 mm.
The posterior interosseous nerve winding around the radial neck at the level of the radial head is vulnerable during lateral elbow surgical approaches extending distal to the radiocapitellar joint, particularly in direct radial head replacement and radial neck plating, causing wrist and finger extensor weakness.
