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Purpose of this study was to control the suitability of Navi-Robot, a robotic system developed by our research group, to guide percutaneous needle placement under computed tomography (CT) in order to achieve lower radiation exposure and a shorter procedure. The system consists of a high precision six-degrees-of-freedom self-balanced arm, able to move both in passive and active modes, which allows the physician an accurate needle-insertion. The target and the needle entry points are selected by the surgeon on a desktop computer, that acquires DICOM images from the CT scan, and that, using software developed for this purpose, detects also the position of at least three radio opaque markers placed on the patient or on the stretcher. Once these data are obtained, a new system of reference is established based on the markers position, obtaining the coordinates of target and entry point in the new frame of reference. Going then to touch the tip of the spheres with the tip of the robot end effector in passive mode, and recording their position, the robot learns where the two points of interest are located in its frame of reference. A first test was performed on a Plexiglas board; the accuracy achieved was measured as the distance between the needle tip and the target. The results of the in vitro experiment showed that the system is able to reach the target with an accuracy of 1.2 mm.

It was found that the proposed system is effective for developing patient-oriented video-games for rehabilitation. The two main advantages are that the therapist is allowed to (i) develop personalized video-games without informatics skills and (ii) adapt the game settings to patients affected by different pathologies. Implications for rehabilitation Virtual reality and serious video games offer the opportunity to transform the traditional therapy into a more pleasant experience, allowing patients to train their motor and cognitive skills. Both the therapists and the patients should be involved in the development of rehabilitative solutions to be highly patient-oriented. A system for the design of rehabilitative games by the therapist is described and the feedback of three therapists and six patients is reported.

Hinged external fixators are used in knee dislocation treatment, where they have shown their effectiveness. They are proposed as a technique to protect ligament reconstructions while allowing early postoperative rehabilitation. A hinged external fixator usually consists of two rigid links connected to each other by a revolute joint. Each link is then fixed to the femur and tibia, via direct pin fixation. A single-axis hinged external fixator thus well accommodates the main knee movement, i.e. the flexion and extension. This paper presents an investigation on the conceptual idea of a double-axis hinged external fixator for the human knee, which accommodates for both flexion-extension and longitudinal internal-external rotation of the tibia respect to the femur. The potential advantage of such a design is foreseen in the increasing range of motion in postoperative knee rehabilitation and a better accommodation of natural knee motion.