Most fractures of the radial head involve a component of articular impaction in addition to shear. The simplest pattern of displacement involves failure of a margin of the head in compression. Higher energy injuries involving the radial neck often occur in the setting of associated failure of the soft-tissues of the elbow and/or forearm. A common injury pattern involves a radial head fracture, coronoid fracture and elbow dislocation (the “terrible triad”) with collateral ligament disruption. Elbow dislocation is seen in up to 10% of radial head fractures.
Internal fixation of the radial head is technically demanding due to the small and often comminuted nature of the fragments as the circumferential articular cartilage on the head. When the fracture involves only a segment of the radial head, K-wires are replaced with small compression screws for definitive fixation. Two millimeter and occasionally 1.5 mm implants are most commonly used. Care must be taken not to penetrate the opposite cortex and the screw heads are countersunk beneath the articular surface.When comminution extends down the radial neck, small 2.0 mm and 2.4 mm plates are commonly utilized to stabilize the radial head. When used, plates must be applied in the “safe zone” of the radial head that does not articulate with the sigmoid notch of the proximal ulna, defined as the quadrant located laterally with the forearm in neutral rotation or posteriorly in supination.
When radial head fractures are too comminuted to allow for stable internal fixation, a decision must be made whether to excise or replace the head. With intact ligaments, resection will not result in motion loss but will lead to weakness in grip and forearm loading. In fractures with associated elbow joint dislocation or forearm interosseous ligament failure, resection is contraindicated. In this setting, implants are required to restore the valgus and axial load bearing functions of the radial head and allow proper healing of the soft-tissues.
