Avoiding articular breakthrough in screw fixation of radial head fractures

BACKGROUND: The radial head is anatomically complex, making fracture fixation challenging because of the difficult visualization of the articular surface. As a result, screw penetration into the radiocapitellar joint can often occur. To facilitate safe placement of screws tangential to the joint surface, we define an approximate and reliable distance from the articular rim of the radial head that can minimize the risk of articular breach. METHODS: A Kirschner wire for cannulated drilling was placed tangential to the articular surface in 15 cadaveric proximal radii. The distance from the wire to the articular rim was measured 3 times. After insertion of a 3.5-mm compression screw, the radial head was divided in the coronal plane, bisecting the screw track, to visualize the cross section of the screw's position. Headless compression screws of 3.5 mm were placed the distance from the most proximal edge of the screw track to the radial head's articular surface was measured 3 times. RESULTS: The average distance from the articular rim to the distal surface of the Kirschner wire was 5.1 mm. The average distance from the articular rim to the proximal edge of the cavity was 1.7 mm. The screw placement was subchondral and extra-articular in all cases. CONCLUSION: When fixing Mason type 2 articular radial head fractures with 3.5-mm headless compression screws placed tangential to the articular surface, maintaining a screw entry point about 5 mm distal to the articular surface of the radial head will minimize the possibility of articular screw breach. This position also places the screw into subchondral bone, providing the best bone quality for mechanical support.