In severe injuries of the radial head with multiple, displaced fracture fragments and concomitant ligament damage, excision of the fragments and replacement of the radial head with a metallic implant are indicated. Current radial head implants are composed of metal or a combination of metal and high molecular weight polyethylene. The prostheses are assembled intra-operatively as a solid unit (monopolar) or as an articulating implant with motion between the stem and head (bi-polar). The stem of the implant is inserted into the proximal radius for support and can be classified as either loose-fitting or fixed. According to the investigators, there are no studies that directly compare the clinical and radiographic outcomes between different radial head implant designs. The purpose of this retrospective study is to compare the clinical and radiographic results in patients treated for an irreparable radial head fracture with either a smooth stem, bipolar radial head implant or a monopolar, in-growth radial head implant. The study findings may provide useful clinical information regarding the similarities and differences in these two implant designs.