Orthopedic implant sizing instruments, systems, and methods for use during arthroplasty procedures, for example, radial head arthroplasty procedures, are provided. The sizing instruments include at least one sizer head having at least one visualization window or slot provided therethrough for allowing a user to visualize associated surgical structures or surfaces to ensure proper joint reduction. The orthopedic implant sizing instruments, systems, and/or related methods can utilize sizer heads and/or windows having a plurality of different sizes and/or shapes.
