Implant system for a total ankle replacement, comprising: a tibial implant (1) being designed to be fastened to a distal end (4) of the tibia (T), as well as particularly an intermediate implant (2) and a talar implant (3). According to the invention a separate locking device (11) is provided being designed to be inserted into a first recess (R) of the tibia (T) extending along said distal end (4) of the tibia (T), wherein the tibial implant (1) comprises a peg (12) protruding from a base (1a) of the tibial implant (1), which peg (12) is designed to be inserted into a second recess (R') in said distal end (4) of the tibia (T), which second recess (R') particularly communicates with the first recess (R'), and wherein when the locking device (11) is inserted into the first recess (R) and the peg (12) is inserted into the second recess (R') the locking device (11) is designed to fasten the peg (12) and thereby the tibial implant (1) to the locking device (11).
