A device for measuring displacement of the tibia in relation to the femur in response to an applied force or torque on the tibia comprises a first shaft being tiltable about a first axis close to the ankle and approximately parallel to the coronal plane of the patients body, a second shaft being connected to said first shaft and being rotatable about a second axis perpendicular to said first axis, and being close to the ankle and approximately parallel to the tibia, a foot support platform being mounted on said second shaft, the foot support platform having means for attaching the foot thereto at a fixed position, and a displacement test device for applying forces to the tibia and measuring the shift or displacement of the proximal tibia relative to the distal femur.
