Embodiments of the invention may provide a stem and a head and a liner that can be assembled together to form an implant, such as may be used in repair of the distal ulnoradial joint. A given head and liner and stem may be assembled to each other in more than one configuration, providing more than one possible external shape for a given set of stem and head and liner. The head may be non-symmetric about its midplane and may be open at both ends. A kit may contain more than one head assemblable to a given stem with an intermediate liner, with the various heads providing various different external shapes of the device.
