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At least 685 records · Page 38Linked to original sources
PubMed2003

The influence of stem insertion rate on the porosity of the cement mantle of hip joint replacements.

This study investigates the effect of stem insertion rate on the porosity of the cement mantle. An experimental protocol was developed to simulate the surgical technique of cementing a prosthetic stem into the medullary canal of the femur. Cement mantle specimens were produced for three different stem insertion rates. The presence of porosity in the cement mantle was investigated. Additionally, the mechanical strength of the bone cement was assessed. Increasing the stem insertion rate did not have a significant effect on the porosity distribution within the bulk cement mantle. However, for all stem insertion rates investigated, the porosity concentration increased significantly moving from the cement/pseudofemur interface through to the stem/cement interface. In all cases, the presence of porosity significantly decreased the mechanical behaviour of the bone cement. High porosity concentration at the stem/cement interface seems to be attributed also to the rheology of the cement during implant insertion. Nevertheless, the surgeon cannot influence the formation of porosity by changing the stem insertion rate.

Arthroplasty, Replacement, Hip↗
PubMed1995

Three-dimensional imaging of craniomaxillofacial structures with a standard personal computer.

OBJECTIVE: To implement 3D-reconstruction of CT and MR data by a standard MS-DOS personal computer. METHODS: User-specific software has been developed for the 3D-reconstruction and quantitative evaluation of hard and soft tissues of the skull. RESULTS: The software displays a 3D-reconstruction and secondary reformatted vertical sections within 4-30 s on the monitor. The 3D-structures can be evaluated quantitatively with a freely-superimposable grid. Distances or angles between two landmarks can be measured directly. Various tools for the simulation of surgical treatment are available. CONCLUSIONS: Gross skeletal and soft-tissue malformations, topographical relations and the degree of asymmetry of severe maxillofacial deformities can be evaluated in more detail. Access to a readily available low-cost computer system for 3D-evaluation of the head will enable a larger number of clinicians to use 3D-methods in diagnosis and treatment planning. The off-line computing system permits a higher of flexibility independent of any computing centre.

Anatomy, Cross-Sectional↗
PubMed2001

Accuracy of volumetric measurements after virtual right hepatectomy in potential donors undergoing living adult liver transplantation.

OBJECTIVE: The purpose of this study was to evaluate accuracy for determining the total and lobar liver volumes using a multidetector CT scanner in potential donors undergoing living adult right lobe liver transplantation. SUBJECTS AND METHODS: Fifty-two adult donors underwent CT using a multidetector scanner after IV injection of 180 mL of contrast material. For volumetric determination, portal venous phase images were acquired at 60 sec. Hand-tracing was used to isolate the entire liver, and a curved hepatectomy plane was then identified in a manner simulating the surgical incision. Two observers performed hand-tracing of the entire liver to calculate total liver volume, and of the right lobe to calculate expected graft volume. RESULTS: The mean volume of the entire liver, right lobe, and left lobe was 1807 mL, 990 mL, and 817 mL, respectively, for observer 1, and 1788 mL, 1007 mL, and 781 mL, respectively, for observer 2. There was significant agreement between the two observers in determining total and lobar liver volumes (r = 0.996, 0.977, and 0.965 for total, right lobe, and left lobe volumes, respectively; p< 0.0001). There was no statistically significant difference between the two observers in measuring total or lobar liver volumes (p< 0.0001). There was significant agreement between right lobe volume measured by each observer and graft weight obtained in 14 donors at surgery (r = 0.898 and 0.879, for observers 1 and 2, respectively; p <0.001). CONCLUSION: Total and lobar volume determinations after virtual right hemihepatectomy provides accurate and reproducible information that is critical in selecting potential living liver donors.

Adolescent↗
PubMed2004

C-arm-based mobile computed tomography: a comparison with established imaging on the basis of simulated treatments of talus neck fractures in a cadaveric study.

OBJECTIVE: To analyse the image quality and diagnostic effectiveness of a new C-arm-based 3D imaging method (C-arm-CT) for intraoperative evaluation of screw osteosyntheses adjacent to a peripheral joint. MATERIALS AND METHODS: Insertion of screws into four cadaveric specimens simulated the surgical treatment of talus neck fractures. Ten orthopedic surgeons and 10 radiologists evaluated X-ray, C-arm fluoroscopy, C-arm-CT and CT images. RESULTS: The best image quality was obtained with X-rays (p < 0.001), followed by C-arm fluoroscopy (2D) and CT, with the C-arm-CT (3D) being rated lowest (p < 0.001). The most correct diagnoses were obtained with CT and C-arm-CT (with no statistical difference between them), while C-arm-fluoroscopy was inferior (p < 0.001) and X-rays were the worst (p < 0.05). CONCLUSIONS: Even if the image quality of C-arm-CT is definitely inferior to that of CT, screw misplacements can be reliably detected using C-arm-CT. As compared to the current standard procedures (intraoperative fluoroscopy and postoperative radiography), C-arm-CT performed better. C-arm-CT is ideally suited to the intraoperative diagnosis of high-contrast inquiries like bone fragments and OS material, especially at the extremities. Coupling of the new 3D imaging to existing navigation systems is possible. C-arm-CT will support the further development and implementation of open and minimally invasive surgical procedures.

Bone Screws↗
PubMed1998

Virtual environments for training critical skills in laparoscopic surgery.

Surgical training simulations must incorporate not only advanced technical features, such as detailed geometric organ models and physically-based modeling techniques, but also a thorough understanding of the major training issues relating to a particular procedure. We have developed a prototype environment for training laparoscopic cholecystectomy, or gallbladder removal surgery, which focuses a student's attention on the critical steps performed during the procedure and provides feedback as to the common errors committed during a session. The current version of our system runs in real-time on a mid-range graphics workstation. The simulation also provides a platform for research into a variety of different areas, including tissue modeling, finite element methods, and generalized simulation authoring.

Algorithms↗
PubMed2000

Pulsatile expansion therapy for orbital enlargement.

Experimental and clinical investigations have documented the modulatory role of the globe in the development of the orbit. In cases of absence or early loss of the globe, severe hypoplasia of the orbit and midface has been reported by several authors. Statical conformers and orbital osteotomies have been used to correct the resulting facial asymmetry. When replacing such conformers by increasingly larger ones, orbital structures are negatively influenced by the repeated trauma of surgical interventions. Simulating the modulatory role of the globe on orbital growth was the objective when developing a pulsatile device for orbital enlargement in cases of anophthalmia and microrbitism. The design, application and preliminary experience with a dynamic, pulsatile expanding system are presented.

Anophthalmos↗
PubMed2000

[Primary epiploic appendicitis: clinical and radiological diagnosis].

BACKGROUND: Torsion of appendices epiplocae leads to an ischemic infarct of surrounding adipose tissue, causing a syndrome, called "primary epiploic appendagitis" characterized by acute abdominal pain that can simulate a surgical clinical picture. AIM: To describe the clinical picture, ultrasonographic and computed tomographic features of primary epiploic appendagitis. MATERIAL AND METHODS: A report of patients with acute abdominal pain whose diagnosis was a primary epiploic appendagitis, diagnosed and treated in a period of 48 months. RESULTS: Fifty five patients (45 males) aged 16 to 76 years old are reported. Their clinical presentation was acute abdominal pain in the left abdominal quadrant in 48, pain in the right lower quadrant in 4 and epigastric pain in two. Two had mild fever and 12 had nausea. Ten perform physical activities prior to the onset of pain. Imaging examinations showed a 1.5 to 5 cm diameter, uncompressible small mass of adipose origin, located anteriorly and anterolaterally, between the colon and the abdominal wall. There were inflammatory phenomena surrounding the lesion and thickening of the neighboring parietal peritoneum. In all cases, the mass gradually subsided with medical treatment. CONCLUSIONS: Primary epiploic appendagitis is a relatively frequent cause of spontaneously resolving abdominal pain. It is diagnosed by ultrasound or CT scanning.

Abdomen, Acute↗
PubMed2000

[Physical reproduction of cardiac sutures. A new field of investigation in cardiology].

A new technique of physical reproduction of cardiac anatomy has been developed from volumetric data and its practical value assessed in cardiological practice. The acquisition of the volumetric data was by 3D echocardiography. Parallel and equidistant 2D views were selected from this information. The images were printed at a scale adjusted to the true dimensions of the structures of interest and then stuck on a support, the thickness of which was identical to the distance between the views, and the slices were superimposed while respecting the initial orientation. This technique has been adapted secondarily to modern industrial processes of rapid prototyping (3D printing and powdering) allowing automatic tooling of models. Several physical models have been made: whole heart in end diastole, mitral valve stenosis and prolapse, atrial septal defect with insertion of a percutaneous prosthetic device, great vessels at the base of the heart. There are many possible cardiological applications of physical models: investigation of complex cardiac disease, pre- and per-operative simulation of surgical procedures, elaboration of prosthetic material, physiopathological studies, teaching and training, patient information.

Echocardiography↗
PubMed1999

Simulation and virtual reality for surgical education.

Rapid advancements in technology have dramatically changed the way our daily activities are conducted. In the practice of medicine and surgery, technological advances over the past few decades have had an enormous impact on the diagnosis and treatment of disease. In contrast, our methods of teaching surgeons to perform operations remain mired in the 100 year old Halstedian apprenticeship model. In this system, surgeons often learn to operate based on the principle of "see one, do one, teach one." Educational opportunities are largely dependent on chance as a patient with a particular disease pattern must present to the surgeon in order to achieve specific educational goals. Live patients are often used as the initial "practice session" for the learning surgeon in this model of education.

Journal Article↗
PubMed2003

A mobile and navigated image viewer for surgery--evaluation of precision.

We report work on a newly developed and ultra compact mobile viewing device, called NaviView to display medical imaging data (i.e. from a computer tomograph--CT) in situ. The system comprises an optical tracking system to detect both the patients and the viewing devices position and display a proportionable part of the medical image data on a mobile viewing device. This article describes experiments carried out to evaluate the overlay precision of two different imaging modalities (i.e. live video and CT) being visualized.

Computer Simulation↗
PubMed2004

Physics-based preoperative approach planning using hybrid virtual bodies.

This paper proposes a hybrid model mixing geometry and volume data to improve representation of virtual bodies. This model applies object-oriented data models and rendering techniques to virtual organs, and enables both interactive VR simulation and detailed volume visualization of tissue of interest (e.g. coronary). Also, a physics-based framework interactively simulates estimated surgical fields which are used in preoperative discussion. Based on the proposed methods, a VR-based strategic planning system is developed. The system does not need high cost manual segmentation of patient dataset and efficiently supports planning of surgical approaches in cardiovascular surgery.

Humans↗
PubMed2006

Highly-realistic, immersive training environment for hysteroscopy.

The primary driving application of our current research is the development of a generic surgical training simulator for hysteroscopy. A key target is to go beyond rehearsal of basic manipulative skills, and enable training of procedural skills like decision making and problem solving. In this respect, the sense of presence plays an important role in the achievable training effect. To enable user immersion into the training environment, the surrounding and interaction metaphors should be the same as during the real intervention. To this end, we replicated an OR in our lab, provided standard hysteroscopic tools for interaction, and generate a new virtual scene for every session. In this setting, the training starts, as soon as the trainees enter the OR, and ends when they leave the room.

Competency-Based Education↗
PubMed2006

[Teaching arthroscopy techniques at the Educational Center for Clinical Anatomy and Endoscopy (ECAE), Department of Anatomy, 3rd Faculty of Medicine, Charles University in Prague].

In the period from 2000 to 2005, with support of several grants, a unique multi-media center for teaching endoscopic techniques was established at the Department of Anatomy, 3rd Faculty of Medicine, Charles University in Prague. This conditions have been provided for the repeated use of cadavers preserved by a special embalming method of Professor Thiel of the Institute for Anatomy, University of Graz, for simulation of surgical procedures. One room of the Department has been converted into a small operating theatre and an audio-visual network with wireless Internet connection covers the whole dissection unit of the Department. A graphic studio for production of teaching materials has also been set up. The course in dissection for the first- and second-year medical students also includes demo arthroscopy. In addition to the courses for students, postgraduate courses for young surgeons are organized. These provide an opportunity to learn about techniques and instruments employed in a broad range of arthroscopic procedures, using appropriate cadaver materials.

Arthroscopy↗
PubMed1989

Basilar crescentic osteotomy. A three-dimensional computer simulation.

A three-dimensional computer simulation of the basilar crescentic osteotomy has been presented. The bunion deformity consists of hallux valgus, an increased first and second intermetatarsal angle, pronation of the great toe, and elevation of the first metatarsal head. Every foot is different and some may have more or less of each of the above noted components. Because the deformity is multiplanar, at least two roentgenograms are needed to evaluate the deformity. The weight-bearing, anterior-posterior roentgenogram is the principle radiograph used in preoperative planning. The use of a weight-bearing, sesamoid roentgenogram is recommended to quantify the anterior-posterior deflection and rotation of the first metatarsal head. A computer model (based on a cylinder) of the first metatarsal has been formulated. The osteotomy then was performed in a variety of scenarios in order to simulate the surgical correction. A great deal of flexibility is afforded by this osteotomy. The surgeon needs to be aware of the coupled motions that occur. That is, closure of the intermetatarsal angle may also cause head rotation, depression, or elevation. If the osteotomy is performed in an oblique multiplanar direction, then it is possible for the metatarsal head to elevate, pronate, and significantly shorten as the intermetatarsal angle is closed. If this scenario should occur, a poor surgical outcome will result. Excision of the medial eminence is recommended after the osteotomy has been completed and secured with stable fixation because of these rotational changes. The basilar crescentic osteotomy is an excellent method for correction of a marked metatarsus primus varus. It is important to pay close attention to a variety of anatomic considerations. The osteotomy must not be made in the diaphysis because of potential nonunion. There should be little dissection of the periosteum because of possible delayed union. As in any bunion surgery, it is essential to perform an adequate, distal, soft-tissue repair. Three dimensional preoperative planning is essential in obtaining correction of all components of a bunion. Specific guidelines, based on a three-dimensional computer model, are now available. An interactive computer program also is available to aid the surgeon in preoperative planning. We hope there will be better understanding of this technically difficult but highly versatile osteotomy.

Hallux Valgus↗
PubMedDate not supplied

Computed tomography in the diagnosis and treatment of mediastinal abnormalities in children.

Thirty-one children with mediastinal abnormalities--14 malignant lymphomas, 4 other primary malignancies, one metastatic and 12 benign lesions--were examined one or several times using CT, which proved to be effective especially for cysts (5 patients), ductus arteriosus aneurysm (2 patients), and intrathoracic liver (one patient). It also supplied important diagnostic information regarding the extent of disease in malignant thymoma (one patient), in neurinoma (one patient), and in Hodgkin's lymphoma (5 patients). It was found to be useful in the monitoring of treatment of patients with lymphomas, in which a small residue, probably a fibrotic remnant, was invariably seen after completion of chemotherapy and irradiation. It was concluded that when the residue was enlarged, the possibility of relapse and even thymic hyperplasia should be considered. However, if CT was performed under general anaesthesia pseudo-widening of the anterior mediastinum could simulate recurrence. Surgical biopsy was found to be necessary in these cases because fine-needle aspiration biopsy was unsuccessful.

Child↗