An orthopedic trial implant assembly configured to be implanted in a proximal radius, comprising: at least one radial trial implant including: a head body that defines a proximal head body surface and a distal head body surface opposite the proximal head body surface substantially along a longitudinal direction, and the head body has a height that extends from the proximal head body surface to the distal head body surface along the longitudinal direction; and a stem that extends from the head body along a distal direction that is substantially defined by the longitudinal direction; and at least one spacer that is configured to removably attach to the radial trail implant along a direction substantially perpendicular to the longitudinal direction so as to define a composite head including the head body and a spacer head of the spacer, wherein the composite head defines a proximal composite head surface and a distal composite head surface opposite the proximal composite head surface along the longitudinal direction, and the composite head defines a composite head height from the proximal composite head surface to the distal composite head surface, wherein one of the proximal composite head surface and the distal composite head surface is defined by the head body, and the other of the proximal composite head surface and the distal composite head surface is defined by the spacer head, and wherein the composite head height is greater than the head body height, characterized in that the distal head body surface defines a plurality of cutting teeth configured to planarize the radius as the head body is rotated about its central axis that is oriented along the longitudinal direction. at least one radial trial implant including: a head body that defines a proximal head body surface and a distal head body surface opposite the proximal head body surface substantially along a longitudinal direction, and the head body has a height that extends from the proximal head body surface to the distal head body surface along the longitudinal direction; and a stem that extends from the head body along a distal direction that is substantially defined by the longitudinal direction; and a head body that defines a proximal head body surface and a distal head body surface opposite the proximal head body surface substantially along a longitudinal direction, and the head body has a height that extends from the proximal head body surface to the distal head body surface along the longitudinal direction; and a stem that extends from the head body along a distal direction that is substantially defined by the longitudinal direction; and at least one spacer that is configured to removably attach to the radial trail implant along a direction substantially perpendicular to the longitudinal direction so as to define a composite head including the head body and a spacer head of the spacer, wherein the composite head defines a proximal composite head surface and a distal composite head surface opposite the proximal composite head surface along the longitudinal direction, and the composite head defines a composite head height from the proximal composite head surface to the distal composite head surface, wherein one of the proximal composite head surface and the distal composite head surface is defined by the head body, and the other of the proximal composite head surface and the distal composite head surface is defined by the spacer head, and wherein the composite head height is greater than the head body height, characterized in that the distal head body surface defines a plurality of cutting teeth configured to planarize the radius as the head body is rotated about its central axis that is oriented along the longitudinal direction.