Clinical outcomes for total knee arthroplasty (TKA) are sensitive to lower extremity alignment, implant positioning, and implant size. Accurate determination of femoral implant size is the focus of this paper. As existing methods (conventional instrumentation, preoperative images, navigation) can be limited by issues including inaccuracy, time required, exposure, and cost, this study assesses a novel method for determining femoral component size using navigation.We used a commercially available navigation system (Exactech GPS, Blue Ortho, Grenoble, FR, with Total Knee V1.13 software). The system uses surface patches to collect small point clouds, and then computes points that match a given criteria (e.g. the most distal point). For femoral component sizing, the proposed method automatically defines a target area to be digitised on the anterior cortex.To do this, the surgeon acquires anatomical landmarks (i.e., knee centre, distal condyles, etc.) for all femoral implant parameters but the size. The surgeon...

Cet article présente les travaux réalisés au cours du projet Surgicobot auquel ont contribué deux laboratoires de recherche, deux équipes chirurgicales et deux industriels, dont l’un sera le vecteur de dissémination des résultats du projet. L’objectif de ce projet est de fournir une aide aux futurs chirurgiens pour réaliser de façon sûre et rapide les gestes de libération de la moelle épinière (laminectomie) dont l’indication augmente avec le vieillissement de la population. Le système comprend les sous-systèmes principaux suivants : un « cobot » (robot collaboratif) tenant l’outil de fraisage conjointement avec le chirurgien et capable d’exercer des efforts afin de l’empêcher de pénétrer dans des zones critiques, un système de navigation comprenant une caméra vidéo et ses cibles associées permettant de localiser précisément l’outil et la zone de travail, et un logiciel graphique dont le rôle est tout à la fois de réaliser les calculs géométriques nécessaires à la définition et à la représentation des zones à protéger, et de superviser de façon interactive l’ensemble des taches allant de l’imagerie préopératoire à la visualisation de l’opération elle-même. Le projet a permis de faire évoluer significativement l’ensemble des sous-systèmes et le prototype complet a été validé sur un mannequin en effectuant la totalité du scénario pré- et peropératoire.

To obtain a long lifespan of knee prosthesis, it is necessary to restore the alignment of the lower limb. In some cases of severe arthrosis, the ligament envelope of the joint may be deformed, inducing an asymmetric laxity once the lower limb is realigned. Because there is not yet unanimity regarding how to optimally measure or implement soft tissue balance, we provide a means to acquire a variety of measurements. In traditional surgery, the surgeon sometimes uses a “tensor”, which acts like a forceps. This system was redesigned, instrumented, actuated, and integrated into a navigation system for orthopaedic surgery. Improving the perception of the surgeon, it helps him to address the ligament balancing problem. Our first prototype has been tested on sawbones before being validated in an experiment on two cadavers. In our first attempt, the surgeon was able to assess soft tissue balance but judged the device not powerful enough, which led us to develop a new more powerful hydraulic system. In this paper, we present our approach and the first results of the new hydraulic tensor which is currently in an integration process. Copyright © 2005 John Wiley & Sons, Ltd.

The objective of this work was to design a compact, accurate, safe, and ease-to-use surgical robot for total knee arthroplasty. The goal of the bone-mounted robot, named Praxiteles, is to precisely position a surgical bone-cutting guide in the appropriate planes surrounding the knee, so that the surgeon can perform the cuts manually using the guide. The robot architecture is comprised of 2 motorized degrees of freedom (DOF) whose axes of rotation are arranged in parallel, and are precisely aligned to the implant cutting planes with a 2 DOF serial adjustment mechanism. An initial prototype was first developed and tested on saw bones and cadavers, and construction of a new, refined version is now well underway. A backdrivable system, with high-stiffness, high-precision static positioning capabilities and safe low-force dynamic movement is achieved using a quick-release, spring-loaded mechanical braking system integrated in a gear transmission unit at the level of the motor outputs. This paper discusses the technical challenges encountered during the development, design, and construction of the system.

Démontrer sur quelques exemples les potentialités des Gestes Médico-Chirurgicaux Assistés par Ordinateur. Quatre produits ou prototypes seront démontrés en permanence sur le stand I4 « GMCAO ». Les visiteurs pourront s’initier à une pratique innovante d’interventions médicales ou chirurgicales. Station SURGETICS® de PRAXIM-Medivision : station de navigation chirurgicale stratégies planifiée et réalisée sont comparées (à partir de données pré-opératoires de type tomodensitométrie ou IRM, ou à partir de données géométriques ou dynamiques acquises pendant l’intervention). Par exemple : chirurgie orthopédique, chirurgie de la base du crâne par voie ORL, chirurgie dentaire, ponction de rein sous guidage échographique. RPL (Robot de Ponction Léger sous scanner ou sous IRM). Ce prototype a pour objectif de transformer tout scanner ou IRM en scanner ou IRM interventionnels. Son architecture très particulière (parallèle et séquentielle) lui permet de suivre naturellement les mouvements physiologiques du patient (respiration par exemple). TER (Télé-Echographie Robotisée). Ce robot léger et intrinsèquement compliant permet à un opérateur distant de prendre complètement le contrôle d’un examen échographique. REL (Robot Endoscopique Léger). Ce robot permet de contrôler l’orientation et le zoom d’une caméra endoscopique. Il offre une « troisième main » au chirurgien. Les convergences entre GMCAO et radiologie interventionnelle sont multiples et fructueuses.

Research on "Computer Assisted Medical Interventions" (CAMI) was initiated in Grenoble in 1984, as an attempt to take up the challenge of "Minimally Invasive Interventions", thanks to the introduction of Information and Communication Techniques in the Operating Room. In a first section, we will describe our initial vision. The corresponding achievements will then be presented. A final section will show that the challenge now is to "invert this movement": instead of moving the computer in the Operating Room, we should embed the surgeon (or at least his or her expertise) into the Information Technology based tools he or she uses.

Démontrer sur quelques exemples les potentialités des Gestes Médico-Chirurgicaux Assistés par Ordinateur (GMCAO). A partir de données pré-opératoires de type tomodensitométrie ou IRM, ou à partir de données géométriques ou dynamiques acquises pendant l’intervention sur une station SURGETICS® de PRAXIM-Medivision (station de navigation chirurgicale), des stratégies planifiées et réalisées sont comparées. Par exemple : chirurgie orthopédique, chirurgie de la base du crâne par voie ORL, chirurgie dentaire, ponction de rein sous guidage échographique. RPL (Robot de Ponction Léger sous scanner ou sous IRM). Ce prototype a pour objectif de transformer tout scanner ou IRM en scanner ou IRM interventionnels. Son architecture très particulière (parallèle et séquentielle) lui permet de suivre naturellement les mouvements physiologiques du patient (respiration par exemple). TER (Télé-Echographie Robotisée). Ce robot léger et intrinsèquement compilant permet à un opérateur distant de prendre complètement le contrôle d’un examen échographique. REL (Robot Endoscopique Léger). Ce robot permet de contrôler l’orientation et le zoom d’une caméra endoscopique. Il offre une « troisième main » au chirurgien. Quatre produits ou prototypes seront démontrés en permanence sur le stand 14 « GMCAO ». Les visiteurs pourront s’initier à une pratique innovante d’interventions médicales ou chirurgicales. Les convergences entre GMCAO et radiologie interventionnelle sont multiples et fructueuses.

We discuss 3D bone surface reconstruction from a set of few digital X-ray projections acquired with a mobile C-arm system. We first show the C-arm calibration and the modeling of its mechanical deformation. Then a 3D shape reconstruction method based on elastic registration of a statistical model with a set of few projections (2 to 5) is discussed and applied to a lumbar vertebra.

UNLABELLEDTo make the surgical procedure safer and more precise in FESS, a non-invasive markerless computer-assisted system (CAS) is described for intra-operative navigation whenever the critical regions may be affected by surgical manipulation.PATIENTS AND METHODSTwenty patients with benign diseases of the paranasal sinuses were treated by Computer Assisted Video-endoscopic surgery, between December 1997 and March 1998. For the determination of accuracy and reproducibility of the system, ten anatomical landmarks on each side of the paranasal sinuses were chosen and measured. All of these points were identified on the direct live video-endoscopy image and compared to those obtained with the Optical Digitizing System (Flashpoint 5000(R)), on axial, coronal and sagittal view. The Optical Localizer we used detects the position of the relative coordinates of two rigid bodies made of IR-LED's each, one rigid body is secured to the head' of the patient with a headset, so that patient motion can be tracked, and the second rigid body attached to the operating instrument, leading to direct localization of the tip of the instrument. We use a markerless, skin surface-based registration method, which has the advantage to avoid doing a second CT scan examination usually performed to process the position of the fiducial markers. We register the data from the patient's usual paranasal CT scan.RESULTSComputer-assisted surgery does not increase significantly the duration of the operation. Our markerless skin surface points registration method is reliable enabling of the movements patient's head during the procedure. Computer assistance can be used in almost any type of endoscopic sinonasal procedure. We obtained a registration and calibration accuracy of less than 1.5 mm in 89.2% of cases.CONCLUSIONCAS enables the surgeon to have a more thorough understanding of the complicated anatomy of paranasal sinuses, and may be especially helpful in revision surgery when normal anatomic landmarks are lacking. Due to the passive optical technology (Passive Polaris(R)), we are continuing clinical studies in ENT surgery in order do improve the system and to simplify its current management.

This study presents early results of clinical experience with the application of Computer Assisted Surgery (CAS) to percutaneous iliosacral screwing, with comparison to a historical series of patients treated using percutaneous fluoroscopy. Four patients were instrumented using a CAS system, with 10 screws being inserted. Thirty patients were treated by percutaneous fluoroscopic screwing, with 51 screws being inserted. The follow-up assessment included the following criteria; operative time, parameters of radiation exposure, neurological examination, screw placement evaluation on CT-scan, antalgic drug consumption, pain, Majeed grading, and loosening of implants. In the CAS group, the average radiation time was 0.35 min per patient and 0.14 min per screw. No trajectories outside the bone and no postoperative neurological deficits were found. In the fluoroscopic group, the average radiation time was 1.03 min per patient and 0.6 min per screw. Twelve screws had outside-bone trajectories, and iatrogenic neurological deficits were found in seven patients. The average operative time was 50 min in the CAS group and 35 min in the fluoroscopic group. The present CAS technique shows better placement of iliosacral screws, with no outside-bone trajectories and lower radiation exposure.

This study presents early results of the clinical experience of computer assisted surgery (CAS) applied to percutaneous iliosacral screwing. The results of these 10 first cases (4 patients) are compared to an historical series of 51 cases (30 patients). The CAS technique shows better screw placement without outside bone screw and a very low radiation exposure.

The complications associated with misplaced pedicle screws are mostly neurological or vascular. Previous studies of surgical procedures have shown a significant rate of incorrect placement of pedicle screws, ranging from 15% to 40%. To increase the safety of screw placement, a technique that combines preoperative computed tomography (CT) imaging with intraoperative passive navigation is proposed. A combination of registration algorithms is used to match the preoperative model of the vertebra with intraoperative points that are obtained by using a pointer and a 3-dimensional optical localizer. Images and optimal trajectories are then reported in the intraoperative space. The tip and axis of any surgical tool or guide is visualized in real-time in the volume of preoperative CT images to perform the computer-assisted drilling procedure. Ninety-six pedicle screws have been inserted in lumbar and thoracic vertebrae (from T10 to L5) for various spine disorders with the computer-assisted system. Surgery was followed by postoperative radiographs and CT scans, on which measurements of screw position relative to pedicle could be performed. Nine percent to 12% penetration is obtained with the computer-assisted technique; 44% is obtained with the manual insertion. Preoperative errors from the CT scan data (image gap) and intraoperative errors that occur during the collecting of point coordinates may explain the computer-assisted technique failures. The results clearly show that the computer-assisted surgery technique provides much better safety and accuracy than manual insertion. This technology is evolving rapidly and many new extensions will occur in the years to come.

Several authors have employed finite element analysis for stress and strain analysis in orthopaedic biomechanics. Unfortunately, the definition of three-dimensional models is time consuming (mainly because of the manual 3D meshing process) and consequently the number of analyses to be performed is limited. The authors have investigated a new patient-specific method allowing automatically 3D mesh generation for structures as complex as bone for example. This method, called the mesh-matching (M-M) algorithm, generated automatically customized 3D meshes of anatomical structures from an already existing model. The M-M algorithm has been used to generate FE models of 10 proximal human femora from an initial one which had been experimentally validated. The automatically generated meshes seemed to demonstrate satisfying results.