A 3D positional registration system incorporates one or more sensor assemblies positionable at anatomical reference points on or within a patient during repeat examinations. One such sensor assembly includes a mounting base comprising at least one flexible tab, a mounting flange forming a bottom surface of the mounting base, and a ledge positioned between a top surface of the at least one flexible tab and the mounting flange. A sensor housing is positioned on the ledge and rotatably engaged with the mounting base. The sensor housing has a cavity sized to receive a positional sensor and the at least one flexible tab engages an upward-facing surface of the sensor housing.
