Cu(In,Ga)Se2 films were prepared via a sputtering route with a following selenization process. In, CuIn, and Cu3Ga were observed in the precursor films. Selenization at 450 oC yielded monophasic Cu(In,Ga)Se2 films. The diffraction angles of the (112) peaks shifted toward high angles, and a uniform morphology of the obtained films was observed with high-temperature selenization. The amount of gallium ions incorporated into indium ions increased with the temperature. The probable formation mechanism of the sputtering-derived Cu(In,Ga)Se2 was proposed. Firstly, selenium species diffuse into the precursor films to form Cu(In,Ga)Se2 and Cu2−xSe phases. Subsequently, the complete reaction of selenium with residual species leads to the formation reaction of single-phased Cu(In,Ga)Se2. An efficiency of 8.34% was achieved for the fabricated solar cell.

L’orientation tridimensionnelle (3D) de l’acétabulum natif est un sujet fondamental en chirurgie orthopédique. La tomodensitométrie (TDM) permet la réalisation de mesures 3D de cette orientation acétabulaire, mais avec un surcroît d’irradiation non négligeable. En utilisant la stéréoradiographie basse dose EOS, les objectifs de cette étude était (1) de valider la reproductibilité du système de reconstruction sterEOS 3D pour l’acétabulum natif, (2)de donner les valeurs normales de l’orientation de l’acétabulum natif, en fonction du sexe ou du côté, (3) et de rechercher une relation entre l’antéversion acétabulaire et l’incidence pelvienne.Cent soixante-cinq patients asymptomatiques ont réalisé un EOS corps entier (face + profil) pour une étude prospective sur l’équilibre sagittal rachidien. Dans cette population, 102 patients avaient des images permettant l’analyse du bassin et de l’acétabulum, avec une distribution homme-femme équilibrée. Les images EOS ont été reconstruites en 3D grâce au logiciel SterEOS 3D, permettant des mesures 3D automatiques des paramètres acétabulaires (antéversion et inclinaison) et des paramètres pelviens (incidence pelvienne, version pelvienne et pente sacrée) dans deux référentiels : le plan pelvien antérieur (PPA) qui constitue un référentiel anatomique, et le plan vertical patient qui constitue un référentiel « fonctionnel ».Les reproductibilités intra-observateur et inter-observateurs étaient bonnes avec un coefficient de corrélation intra-classe supérieur à 0,9 et les intervalles de Bland et Altman étaient compris dans les limites de concordances. L’Antéversion et l’Inclinaison Acétabulaires Anatomiques (AAA et IAA) étaient significativement plus élevées chez la femme que chez l’homme, mais sans différence droite/gauche (AAA droite : femme 21,3 ± 3,4° versus homme 16,1 ± 3,3° (p < 0,001) ; IAA droite : femme 55,3 ± 3,7° versus homme 52,5 ± 3,0° (p < 0,001) ; AAA gauche : femme 20,9 ± 3,5° versus homme 15,6 ± 4,0° (p < 0,001) ; IAA gauche : femme 54,6 ± 3,5° versus homme 52,7 ± 2,8° (p = 0,003). L’antéversion acétabulaire fonctionnelle était corrélée à des sous-groupes d’incidence pelvienne (<44° ; 44–62°; > 62°).Le logiciel SterEOS 3D avec module pour acétabulum natif était un outil fiable et reproductible. Cette méthode innovante a permis d’obtenir pour la première fois des valeurs de référence de l’orientation acétabulaire 3D en position debout dans une population asymptomatique. Nos résultats ont renforcé le concept des relations hanche/rachis, grâce à une technique d’imagerie à basse irradiation.Étude cas témoin.

Purpose of the study: We describe a surgery navigation system based on virtual fluoroscopy images established with a 3D optic localizer. The purpose of this work was to check the accuracy of the system for posterior spinal implants in comparison with conventional surgery. Duration of radiation and duration of surgery were compared. Material and methods: A 3D optic localizer was used to monitor the position of the instruments in the operative field, as well as the fluoroscopy receptor. The surgeon took two views, ap and lateral, with a total exposure of two seconds. The C arm was then removed. After image correction, the ap and lateral views were displayed on the work station screen where the computer superimposed to tools on each image. Twenty osteosynthesis procedures for implantation of pedicular screws via a posterior approach to the thoracolumbar spine were performed with this virtual fluoroscopy technique (20 patients, 68 screws). During the same study period, twenty other procedures were performed with the conventional technique (ap and lateral x-ray with the C-arm after drilling the pedicle, 20 patients, 72 screws). The position of the spinal implants was compared between the two series on the ap and lateral views and postoperative CT. Similarly time of exposure to x-rays and duration of the surgical procedure were recorded. Results: The rate of strictly intrapedicular implantation was less than 8% (5/68 screws) in the virtual fluoroscopy series versus 15% (11/72 screws) in the conventional series. Time of exposure to radiation was significantly lower in the virtual fluoroscopy series with a 1 to 3 improvement (3.5 s versus 11.5 s on average) over the conventional method. With training, this method is not more time consuming (10 min per screw for the conventional method versus 11.25 min for virtual fluoroscopy). Discussion and conclusion: Compared with conventional fluoroscopy, the virtual technique enables real time navigation while significantly reducing the dose of radiation, both for the patient and the surgery team. There are two types of advantages of virtual fluoroscopy over CT-based systems: first virtual fluoroscopy is immediately available without specific preoperative imaging and secondly it provides real non-magnified images acquired once during the procedure, after which the C-arm is removed. 3D virtual fluoroscopy is probably the next step but requires further experience.

PURPOSE OF THE STUDY:Standard methodology is lacking for evaluating the accuracy of surgical navigation systems. The purpose of the present study was to propose a new approach to error measurements of an image-free navigation system used for total hip arthroplasty.MATERIAL AND METHODS:This new approach evaluates the overall accuracy of the system and quantifies the influence of clinical application on this global error. The majority of hip navigation systems use the anterior pelvic plane as part of the reference system. With image-free systems, anatomic pelvic landmarks must be acquired intraoperatively in order to define the anterior pelvic plane. This step could potentially introduce a significant error for navigation. Two studies were performed to measure this error, one on patients and the other on pelvic phantoms. Both used the difference between the intraoperative cup orientation, as displayed by the navigation system and the postoperative cup position, measured on computer tomography (CT) data. The CT measurements used the same reference system as the navigation system.RESULTS:The intraobserver measurement variability ranged from 48.4 degrees to 49.5 degrees for cup abduction and from 12 degrees to 13.5 degrees for anteversion. The interobserver variability ranged from 47.5 degrees to 19 degrees for cup abduction and from 11.8 degrees to 13.8 degrees for anteversion. Overall errors were calculated for cup abduction and anteversion. Cup navigation was accurate on pelvic bone phantoms. The anteversion error ranged from 0 degrees to 2.5 degrees (mean 0.9 degrees, standard deviation 0.7 degrees). For the clinical study, abduction errors ranged from 2.1 degrees to 16.7 degrees. The mean abduction error introduced by the acquisition of anatomic landmarks was 7.2 degrees.DISCUSSION:The proposed simple clinical end-to-end accuracy evaluation model provides the surgeon with sufficiently accurate information. The evaluation model was able to identify and more importantly to quantify the clinically induced error. This study proves that ameliorating the reference system acquisition would improve the system's overall accuracy.

Purpose of the studyStandard methodology is lacking for evaluating the accuracy of surgical navigation systems. The purpose of the present study was to propose a new approach to error measurements of an image-free navigation system used for total hip arthroplasty.Material and methodsThis new approach evaluates the overall accuracy of the system and quantifies the influence of clinical application on this global error. The majority of hip navigation systems use the anterior pelvic plane as part of the reference system. With image-free systems, anatomic pelvic landmarks must be acquired intraoperatively in order to define the anterior pelvic plane. This step could potentially introduce a significant error for navigation. Two studies were performed to measure this error, one on patients and the other on pelvic phantoms. Both used the difference between the intraoperative cup orientation, as displayed by the navigation system and the postoperative cup position, measured on computer tomography (CT) data. The CT measurements used the same reference system as the navigation system.ResultsThe intraobserver measurement variability ranged from 48.4 degrees to 49.5 degrees for cup abduction and from 12 degrees to 13.5 degrees for anteversion. The interobserver variability ranged from 47.5 degrees to 19 degrees for cup abduction and from 11.8 degrees to 13.8 degrees for anteversion. Overall errors were calculated for cup abduction and anteversion. Cup navigation was accurate on pelvic bone phantoms. The anteversion error ranged from 0 degrees to 2.5 degrees (mean 0.9 degrees, standard deviation 0.7 degrees). For the clinical study, abduction errors ranged from 2.1 degrees to 16.7 degrees. The mean abduction error introduced by the acquisition of anatomic landmarks was 7.2 degrees.DiscussionThe proposed simple clinical end-to-end accuracy evaluation model provides the surgeon with sufficiently accurate information. The evaluation model was able to identify and more importantly to quantify the clinically induced error. This study proves that ameliorating the reference system acquisition would improve the system's overall accuracy.

The present study tested the accuracy of an image-free navigation system used for total hip arthroplasty (THA). Two parallel, prospective studies were performed: one on real patients and the other on pelvic phantoms. We used a comparison between the intra-operative cup orientation, as displayed by the navigation system, and the post-operative cup position, as measured on CT data. The mean intrinsic overall error (± standard deviation) found in the phantom study was 2.6 ± 1.1° (range: 1.5-4.4°) for cup abduction, and 0.9 ± 0.7° (range: 0-2.5°) for cup anteversion. The system was less accurate in the clinical operative setting. The evaluation model was able to identify, and more importantly quantify, the clinically induced error. Ameliorating this would improve the clinical accuracy of the system.

Les systèmes d’imagerie médicale numérique et les techniques informatiques qui sont actuellement développés pour planifier et réaliser certains actes opératoires en chirurgie du rachis procurent au chirurgien orthopédiste une panoplie d’outils performants qui sont capables d’améliorer la précision du geste opératoire, sa fiabilité et le résultat clinique, en même temps d’ailleurs que de permettre une réduction du coût des soins et de la durée de l’hospitalisation. Les principaux systèmes de navigation chirurgicale au niveau du rachis sont équipés de quatre sous-ensembles. 1. Un système de recueil et d’enregistrement des informations numériques spécifiques à chaque patient : images préopératoires (radiographies conventionnelles, tomodensitométries [TDM], imagerie par résonance magnétique [IRM]) ; images peropératoires (fluoroscopie, ultrasons) ; positionnement peropératoire d’outils ou de segments osseux à l’aide de localisateurs tridimensionnels. 2. Un système de recalage permettant de replacer toutes les informations et images numériques dans le champ opératoire du patient en utilisant la fluoroscopie ; les ultrasons ; des repères anatomiques remarquables ou de surface acquis de façon randomisée et aléatoire. 3. Un système d’aide à la décision permettant de planifier le geste opératoire à l’aide d’informations multimodales : positionnement interactif d’outils ou de segments osseux dans le champ opératoire ; éléments prévisionnels de navigation (directions, axes, orientations, longueurs d’un instrument…). 4. Un système d’aide à la réalisation du geste opératoire, permettant de réaliser la stratégie optimale définie en préopératoire : le système est passif lorsqu’il fournit des informations sur la position des outils chirurgicaux dans le champ opératoire ; il est semi-actif lorsqu’il permet de positionner des guides de coupe ou de forage ; il est actif lorsqu’il s’agit d’un robot qui effectue une tâche précise, autonome et déterminée à l’avance. Dans le futur, on peut envisager que les systèmes de navigation chirurgicale au niveau du rachis permettront aux chirurgiens d’évaluer la fiabilité et la précision de différentes techniques opératoires, première étape de l’optimisation des thérapeutiques.

This study presents a clinical validation of postoperative measurements of acetabular cup alignment following total hip arthroplasty (THA). The methodology was based on concurrent anatomic three-dimensional (3D) measurements of both the acetabular cup alignment and pelvic orientation, using an original CT/X-ray matching algorithm named Xalign. The subjects were 19 patients who had undergone bilateral THA using CT-based surgical navigation. All patients had postoperative pelvic CT scans and multiple antero-posterior (AP) pelvic X-rays. Using a proprietary software algorithm, the X-rays included in the study were matched with the corresponding postoperative CT scans. The goal of this method was to allow 3D anatomic pelvic and acetabular measurements on two-dimensional AP X-rays. The postoperative cup abduction, version and pelvic flexion angles were determined in three different ways: using CT images directly, applying the Xalign method, and finally by performing conventional (abduction only) measurements on AP pelvic X-rays. The cup orientation measured on CT images was taken as the ground truth. The Xalign measurement errors were defined as the difference between the CT cup values and those obtained by applying the matching method. The mean cup abduction error was 0.85 degrees +/- 1.3 degrees (+/- standard deviation) and the mean version error was 0.01 degrees +/- 1.99 degrees . Conventionally measured cup abduction ranged from 44 degrees to 62 degrees and correlated significantly (p = 0.001, r = -0.5) with pelvic flexion angle, proving the linear negative correlation between pelvic flexion and the error in conventional radiographic cup measurements. The Xalign method offered reasonable accuracy for cup orientation, and allowed cup and pelvic 3D anatomic measurements at different times.

Abstract Recent advances in hip arthroplasty, including minimally invasive techniques, partial resurfacing, robotics and surgical navigation, need a rigorous and continuous evaluation. The increased accuracy and safety and reduced soft tissue trauma should improve the wear, stability, and functional results. To study the possible benefits of these new technologies, it is important to identify the existing challenges for total hip arthroplasty (THA).

Joint reconstructive surgery is experiencing new and important developments. Less and minimally invasive techniques for hip and knee replacement have been described recently by several investigators. They have outlined not only the positive aspects, but also some of the difficult challenges. Accuracy and safety of the surgery could be increased, despite the smaller approaches, with navigation tools. Although promising,the initial clinical experience is limited and needs to be supported by further, prospective analysis.

Although traditional total hip arthroplasty offers good visualization of bony landmarks and allows for the accurate orientation and fixation of implants, these benefits are achieved at the expense of extensive soft-tissue dissection and can result in postoperative complications and a delayed return to full function. To address these disadvantages, navigational tools were coupled with a mini-incision technique that allowed accurate bone preparation and orientation of the implant components without direct visualization of the bony landmarks. Additionally, image-guided systems provide three-dimensional information before and during surgery, making it possible to know, in real time, the orientation of implants and to visualize the full bony anatomy. This "computer-enhanced vision" allows surgeons to perform less invasive and eventually minimally invasive total hip arthroplasty with improved accuracy.

Summary This study presents early results of the clinical experience of computer-assisted surgery (CAS) applied to percutaneous iliosacral screwing compared with an historical series of patients treated by percutaneous fluoroscopy. Four patients were instrumented with a CAS, with 10 screws being inserted. Thirty patients were treated by percutaneous fluoroscopic screwing, with 51 screws inserted. The follow up included operative time, the parameters of the radiation exposure, the neurologic examination, the screw placement evaluation on computed tomography scan, antalgic drug consumption, pain, Majeed grading, and the loosening implants. In the CAS group, the radiation time by patient was 0.35 minutes and by screw 0.14 minutes. No outside bone trajectories and no postoperative neurologic deficit were found. In the fluoroscopic group, the radiation time by patient was 1.03 minutes and 0.6 minutes by screw. Twelve screws had outside bone trajectories. In 7 patients, iatrogenic neurologic deficit was found. The average operative time was 50 minutes in the CAS group and 35 minutes in the fluoroscopic group. The present CAS technique shows better placement of iliosacral screws without outside bone trajectories and lower radiation exposure.

Purpose: The purpose of this work was to compare the precision and reliability of screw fixation using two different guiding systems. The first system was based on computed tomography (CT) imaging and the second on digitalized fluoroscopic imaging. Material and methods: Between 1998 and 2000, 88 patients underwent spinal fixation for diverse disease states (idiopathic scoliosis in 43, and fracture, spondylolisthesis or instability in 45). Pedicular screws (n = 223) were inserted in levels T4 to S1. The passive CT navigation system was used for 73 patients (177 pedicular screws) and the fluoroscopic navigation system for 15 (46 pedicular screws). An independent observer identified the position of the pedicular screws on the postoperative CT. Results: Among the 73 patients who underwent a CT-guided procedure (177 pedicular screws) the rate of incorrect screw position was 6.2% (11/117) with = 2 mm penetration of the cortical. Among the 15 patients who underwent a fluoroscopy-guided procedure (46 pedicular screws), the rate of incorrect screw position was 17% (8/46) again with = 2 mm penetration of the cortical. For scoliosis patients, the rate of erroneous screw insertion was 6% for CT navigation and 28% for fluoroscopic navigation. For fractures and degenerative instability, the rates were 6% and 11% respectively. Discussion: The passive nature of the two navigation systems used do not induce any peroperative constraint on the surgeon. With the CT system, landmarks have to be collected peroperatively on the posterior arch of the operated vertebra, a step that is not needed for the fluoroscopic system. The two techniques appear to be reliable for insertion of pedicular screws. We did not have any neurological disorders in this series. It can be recalled that the conventional method produces a 15 to 40% rate of erroneous insertion. The CT system provides better results for all types of diseases; the improvement is about 6%. Conclusion: With CT-navigation, a large portion of the per-operative radiographs are no longer necessary. Operative time is slightly longer than for the classical procedure due to the collection of the 3D information, particularly important for scoliosis. With the fluoroscopy system, no special preoperative imaging is required. Two or three peroperative radiographs are sufficient, limiting irradiation during insertion of the pedicular screws. The fluoroscopic system does not however provide 3D images.

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.