Disclosed herein are improved methods, apparatus and/or systems for a tibial implant assembly that can facilitate balancing, positioning, insertion, locking and maneuvering of the modular tibial inserts during knee surgery. The system may include a plurality of modular tibial inserts with locking or engagement mechanisms that allow creation of a modular insert assembly, and a corresponding tibial tray and optional tray components. The system allows the quick and convenient mating and locking of the tibial insert assembly to the tibial tray. The various components can accommodate mobile-bearing and fixed-bearing designs for the tibial tray.