Radial head arthroplasty: A pillar of stability in complex elbow fractures

Figure 1 Mason-Johnston classification of radial head fractures. Type I fractures are non-displaced or minimally displaced injuries of radial head (less than 2 mm) without mechanical block to motion; type II fractures are displaced by more than 2 mm, with potential blocking effect, but lack comminution; type III injuries are both comminuted and displaced; and type IV refers to radial head fractures occurring in the setting of elbow instability.