Innovative endoscopic sino-nasal and anterior skull base robotics.

PURPOSE: Design a compact, ergonomic, and safe endoscope positioner dedicated to the sino-nasal tract, and the anterior and middle-stage skull base. METHODS: A motion and force analysis of the surgeon's movement was performed on cadaver heads to gather objective data for specification purposes. An experimental comparative study was then performed with three different kinematics, again on cadaver heads, in order to define the best architecture satisfying the motion and force requirements. RESULTS: We quantified the maximal forces applied on the endoscope when traversing the sino-nasal tract in order to evaluate the forces that the robot should be able to overcome. We also quantified the minimal forces that should not be exceeded in order to avoid damaging vital structures. We showed that the entrance point of the endoscope into the nostril could not be considered, as in laparoscopic surgery, as a fixed point but rather as a fixed region whose location and dimensions depend on the targeted sinus. CONCLUSION: From the safety and ergonomic points of view, the best solution would be a co-manipulated standard 6-degree of freedom robot to which is attached a gimbal-like passive remote manipulator holding the endoscope.

Computer-assisted and robot-assisted technologies to improve bone-cutting accuracy when integrated with a freehand process using an oscillating saw.

BACKGROUND: In orthopaedic surgery, many interventions involve freehand bone cutting with an oscillating saw. Such freehand procedures can produce large cutting errors due to the complex hand-controlled positioning of the surgical tool. This study was performed to investigate the potential improvements in cutting accuracy when computer-assisted and robot-assisted technologies are applied to a freehand bone-cutting process when no jigs are available. METHODS: We designed an experiment based on a geometrical model of the cutting process with use of a simulated bone of rectangular geometry. The target planes were defined by three variables: a cut height (t) and two orientation angles (beta and gamma). A series of 156 cuts were performed by six operators employing three technologically different procedures: freehand, navigated freehand, and robot-assisted cutting. After cutting, we measured the error in the height t, the absolute error in the angles beta and gamma, the flatness, and the location of the cut plane with respect to the target plane. RESULTS: The location of the cut plane averaged 2.8 mm after use of the navigated freehand process compared with 5.2 mm after use of the freehand process (p < 0.0001). Further improvements were obtained with use of the robot-assisted process, which provided an average location of 1.7 mm (p < 0.0001). CONCLUSIONS: Significant improvements in cutting accuracy can be achieved when a navigation system or an industrial robot is integrated into a freehand bone-cutting process when no jigs are available. The procedure for navigated hand-controlled positioning of the oscillating saw appears to be easy to learn and use.

Development and first in vivo trial of EvoLap, an active laparoscope positioner.

To determine essential specifications for an active endoscope holder, a survey of laparoscopic procedures was conducted. A review of the literature highlighted the advantages and limitations of existing scope-holding systems. From this analysis, basic requirements were listed for such devices. Pursuant to this, an ergonomic and user-friendly laparoscope manipulator was designed to assist the surgeon. A first in vivo procedure demonstrated feasibility of the device and its value in clinical practice, enabling surgeons to work more comfortably.

Design and preliminary in vivo validation of a robotic laparoscope holder for minimally invasive surgery.

BACKGROUND: Manual manipulation of the camera is a major source of difficulties encountered by surgeons while performing minimally invasive laparoscopic surgery. METHODS: A survey of laparoscopic procedures and a review of existing active and passive holders were conducted. Based on these analyses, essential requirements were highlighted for such devices. Pursuant to this, a novel active laparoscope manipulator was designed, paying particular attention to ergonomics and ease of use. Several trials on the pelvitrainer and a first in vivo procedure were performed to validate the original design of our device. RESULTS: Phantom experiments demonstrated ease of use of the robot and advantages of the intuitive joystick with omnidirectional displacements and speed control. The compactness of the device and image stability were appreciated during the surgical trial. CONCLUSIONS: A novel robotic laparoscope holder has been developed and produced. An in vivo trial proved its value in clinical practice, enabling surgeons to work more comfortably.

Accuracy in planar cutting of bones: an ISO-based evaluation.

BACKGROUND: Computer- and robot-assisted technologies are capable of improving the accuracy of planar cutting in orthopaedic surgery. This study is a first step toward formulating and validating a new evaluation methodology for planar bone cutting, based on the standards from the International Organization for Standardization. METHODS: Our experimental test bed consisted of a purely geometrical model of the cutting process around a simulated bone. Cuts were performed at three levels of surgical assistance: unassisted, computer-assisted and robot-assisted. We measured three parameters of the standard ISO1101:2004: flatness, parallelism and location of the cut plane. RESULTS: The location was the most relevant parameter for assessing cutting errors. The three levels of assistance were easily distinguished using the location parameter. CONCLUSIONS: Our ISO methodology employs the location to obtain all information about translational and rotational cutting errors. Location may be used on any osseous structure to compare the performance of existing assistance technologies.

Evaluation of the influence of probe pressure on the B-mode ultrasound measurement of arterial diameter.

This paper deals with the influence of the echographic probe pressure on the measurement of arterial diameter. It is common sense that arterial diameter measurements are affected by the pressure exerted on the B-mode ultrasound probe but we found no report in the current literature analyzing and quantifying this effect. We demonstrated this influence by the analysis of arterial images obtained with a conventional B-mode ultrasound system while monitoring the pressure exerted on the probe with a force sensor. Our preliminary results demonstrated that continuous measurement was feasible and could be used to assess the relationship between the blood pressure and the arterial diameter. This may prove useful for the quantitative evaluation and the follow-up of patients with cardio-vascular diseases.

A hybrid position/force control approach for identification of deformation models of skin and underlying tissues.

In this paper, the focus is on the design of two biomechanical models representing the skin as well as the underlying tissues behavior and properties during a robotized harvesting process. The first model is quasi-static (i.e., without considering velocity) in the pressure direction of the tool: it is principally issued from the work of d'Aulignac et al. and some interesting properties are exhibited from it. The second model is new and takes into account velocity and lubrication in the motion direction of the tool. The goal of this study is to improve skin harvesting process in robotized reconstructive surgery, by automatically selecting the force applied on the donor area and tuning the gain factors of the control law prior to harvesting. It requires extracting relevant parameters such as skin thickness and stiffness, friction coefficient, etc. that characterize the biomechanical properties of the skin and underlying tissues of each patient and of different harvesting surfaces on a given patient (thigh, skull, buttocks, ...). Due to the surgical constraint, the in vivo procedure should be performed in the operating room before starting the operation with the robot itself thanks to a suitable hybrid position/force controller. In this paper, a survey about soft tissue modeling is presented. Mathematical models are discussed along with identification protocols, and two models are chosen that meet our requirements. Finally, experimental results are presented on foam and human skin.