A patient-specific implant includes (a) a body having a convex exterior surface configured to attach to a bone and a concave interior surface configured to receive a head portion of another bone, the body including a plurality of holes extending therethrough, the holes sized and shaped to receive a bone fixation element and (b) a gap filler formed on the exterior surface of the body and having dimensions and a position corresponding to a gap between the exterior surface of the body and the bone to which the implant is to be attached.