The radial head plays an important role in the elbow joint valgus stability in coordination with the medial collateral ligament [1]. Radial head comminuted fractures are often complicated by coronoid process of the ulna fracture, olecranon fracture, and medial/lateral ulnar collateral ligament injuries, and the repair of each injured part is necessary to regain joint stability. However, osteosynthesis for radial head fractures with severe comminution or osteoporosis has a high risk of nonunion and implant failure; therefore, early elbow motion exercises are difficult and elbow stiffness tends to persist [2].

Recently, radial head arthroplasty (RHA) has been performed to allow patients to perform early motion exercises and to regain the stability of the elbow for comminuted fractures that cannot be osteosynthesized. Radial head implants can be broadly categorized as those with loose-fit or press-fit stem and bipolar or monopolar head. To the best of our knowledge, only one study has compared the clinical and radiographic outcomes of loose- and press-fit stems in monopolar RHA [3]. Therefore, this study aimed to evaluate the radiographic and clinical outcomes of the two prosthesis concepts.