The disclosed device for verifying a hip-knee-ankle angle includes a mountingbasehaving a planar abutting surface adapted for direct abutting against aresectedsurface on a distal femur, and a first inertial sensor in communication with acomputer assisted surgery (CAS) system to determine an orientation of themountingbase and to digitize a mechanical axis of the femur. A visual alignment guideelement is pivotably mounted to the mounting base such that the angularposition ofthe visual alignment guide element is adjustable so as to be visually alignedwith amechanical axis of a tibia. A difference between orientations of the mountingbaseand the visual alignment guide is calculated by the computer assisted surgerysystem to determine the hip-knee-ankle angle. The visual alignment guide mayinclude a second inertial sensor and/or a laser emitting element.
