Unicondylar tibia implant devices having a bone-facing, distal side that can be detailed with cement fixation features and may include any of or a plurality of grooves, pegs, fins, rails, cavities, and/or coating whereby the geometry of the implant device improves implant-to-cement or cement-to-bone fixation characteristics exceeding that of a traditional flat surface. The implant device may also include a proximal side facing away from the bone-facing, distal side and having a geometry that provides either articulation with (cartilage and meniscal substituting) or receipt of a secondary device coupleable to the implant device on the distal side of the secondary device that features an away-from-bone facing articulating feature. Additionally, the geometry of the implant device in anterior-posterior and medial-lateral directions, among other directions, provides a variety of improvements relative to currently available devices.