An orthopaedic joint distractor includes a stem post defining a pivoting axis, an actuator configured to cause translational movement of the stem post, a locking sleeve holding the actuator and the stem post, a distractor arc held by the locking sleeve orthogonally to the pivoting axis and having a surface, and a first locking member held by the locking sleeve that can be advanced away from and toward the surface. The first locking member prevents rotation of the distractor arc about the pivoting axis when it has advanced a sufficient distance toward the surface.