A subtalar joint implant (20) is disclosed for replacing a natural subtalar joint existing between the talus (102) and calcaneum (104) bones of a patient. In an embodiment the implant comprises talar (22) and calcaneal (24) portions that are configured to slide over each other in the implanted state. The implant is shaped so that the sliding is constrained to trajectories that involve pivoting of the talar portion relative to the calcaneal portion about a pivot point (36) or a line (38) of pivot points.