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Results for “Surgical simulation”

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At least 469 records · Page 26Linked to original sources

PubMed2002

Hip-Op: an innovative software to plan total hip replacement surgery.

This paper describes an innovative surgical simulation software environment for the pre-operative planning of total hip replacement surgery. The software is a CT-based three-dimensional planning environment, with a user-friendly graphic user interface based on the multimodal display visualization paradigm. Although it relies on a fully three dimensional internal representation, this approach represents the relevant anatomical objects by means of multiple views, each simulating a different medical imaging modality familiar to the medical professional. In the Hip-Op program the multimodal display interface integrates four different display modalities: orthogonal radiographs, Blended slices, CT slices, and arbitrary slices. A conventional surface rendering view is also available. The user 'navigates' the prosthetic components, which are dynamically selected from a library of available parts, within the CT volume while the implant and the patient anatomy are simultaneously rendered in each specialized view. Beside a consideration of anatomical compatibility, the surgeon may evaluate the planned implant type, size and position, also on the basis of two analysis modules that compute the achieved level of implant fitting and filling. After being evaluated in an internal clinical trial, the software is currently made available as freeware at http:// www.ior.it/hipop/.

Algorithms↗

PubMed1998

Technique training: endoscopic percutaneous tracheostomy.

Percutaneous tracheostomy is being used increasingly in the intensive care unit and endoscopic control of this procedure affords an improved level of safety. Training in such new minimal access techniques can be a significant risk factor in patient outcome. Surgical simulation provides training which minimizes this risk. We present a method of training in percutaneous endoscopic tracheostomy using a simulation model based on animal tissue. Our experience with this model is reported.

Animals↗

PubMed2003

Remifentanil and nitrous oxide reduce changes in cerebral blood flow velocity in the middle cerebral artery caused by pain.

BACKGROUND: Cerebral blood flow is affected by painful stimuli, and analgesic agents may alter the response of cerebral blood flow to pain. We set out to quantify the effects of remifentanil and nitrous oxide on blood flow changes caused by experimental pain. METHODS: We simulated surgical pain in 10 conscious volunteers using increasing mechanical pressure to the tibia. We measured changes in cerebral blood flow velocity in the middle cerebral artery (CBFV(MCA)) caused by the pain, using transcranial Doppler sonography. We gave increasing doses of remifentanil (0.025, 0.05 and 0.1 micro g kg(-1) min(-1)) or nitrous oxide [20%, 35% and 50% end-tidal concentration (FE'(N(2)O))] and compared these effects on blood flow changes. RESULTS: Nitrous oxide increased CBFV(MCA) only when given at 50% FE'(N(2)O). Remifentanil did not affect CBFV(MCA). Pain increased CBFV(MCA). Both agents attenuated this pain-induced change in CBFV(MCA) with the exception of nitrous oxide at 20% FE'(N(2)O). CONCLUSIONS: Inhalation of nitrous oxide or adminstration of remifentanil attenuated pain-induced changes in CBFV(MCA).

Adolescent↗

PubMed1982

Nonspecific enhancement of resistance to bacterial infection: evidence of an effect supplemental to antibiotics.

Experiments have been undertaken to further characterize the actions of the synthetic immunoadjuvant compound, muramyl dipeptide (MDP), in an animal model simulating surgical infection. When used prophylactically in combination with antibiotics, MDP proved to be significantly additive in terms of local and systemic effects, and survival, to both chloramphenicol (p less than 0.01) and cephaloridine (p less than 0.05). The combined use of MDP and cephaloridine therapy, initiated four or six hours following infectious challenge and including a surgical foreign body in starved and refed animals, showed statistically significant decreases in bacteremia during early time periods, as well an increased early survival (p less than 0.02), compared with the use of cephaloridine alone. Benefits observed in the therapeutic mode were of lesser magnitude than those observed following prophylactic use, but the model used was a much more significant physiologic challenge. Evidence indicating additive effects to those of antibiotics is essential prior to the use of MDP in clinical trials.

Acetylmuramyl-Alanyl-Isoglutamine↗

PubMed1998

The in utero repair of Tessier number 7 lateral facial clefts created by amniotic band-like compression.

The purpose of this study was to determine the effectiveness of intrauterine reconstruction of lateral facial clefts caused by surgically simulated amniotic band compression. The authors hypothesized that intrauterine lysis of these bands could: 1) prevent the progression of cleft formation; 2) normalize facial development; and 3) allow for the scarless repair of these lateral atypical facial clefts. In a prospective randomized trial, eight 65-day gestational fetal lambs (term, 140 days) were exposed via a maternal hysterotomy. A Tessier 7 facial cleft was made by applying a 2.0 nylon suture as a constriction band to the growing face. The sutures were attached to the zygomatic arch and looped circumferentially into the oral commissure. Two weeks after surgery, four of eight animals were re-exposed. All four animals developed phenotypic changes consistent with Tessier 7 lateral facial clefts. These animals were treated in utero by 1) excising the synthetic constricting band, and 2) opening the epithelialized edges of the lateral facial clefts and performing a primary repair. At birth, the bands on the four untreated animals were cut. The lambs developed to 3 months of age, at which time they were evaluated anthropomorphically for changes in soft tissue measurements, and histologically using hematoxylin and eosin and Mason trichrome stain for the degree of scar at the repair site. Tessier 7 lateral facial clefts were produced in all the untreated animals. Each developed macrostomia with an average 2.3-cm lateral displacement of the oral commissure and partial maxillary clefting induced by the pressure of the restriction band. No evidence of tissue necrosis, maceration, or ulceration was noted. In contrast, animals treated in utero were phenotypically normal. There was no evidence of macrostomia and all anthropomorphic measurements were symmetrical. No bony clefts were seen on gross examination. Histologically, there was no evidence of scar formation at the site of the cleft repair. These findings suggest that like the standard cleft lip, atypical lateral facial clefts can be repaired successfully in utero without scarring. Furthermore, lysis of a restriction band in utero can prevent the progression of this facial deformity, leading to normal development of the face.

Amniotic Band Syndrome↗

PubMed1999

Science education partnership between the University of Colorado and a Denver High School.

The authors describe a partnership, begun in 1997, between Manual High School, a school in which about 85% of the students are African, American or Hispanic, and the University of Colorado Health Sciences Center in Denver. There are three partnership goals: help teachers transform a lecture-based curriculum into an inquiry-based curriculum, help students build their science knowledge, and give students opportunities to learn--and become excited--about careers in medicine. The current emphasis of the partnership is at the ninth-grade level. The first unique aspect of the partnership is the Medical Explorers program. One portion of the program begins when a hypothetical teenage car-crash victim arrives at the emergency room; over the next six weeks, practicing health care professionals dramatize their medical responsibilities to this patient and discuss the academic training necessary to fulfill those responsibilities. In addition, the Medical Explorers students travel to the Health Sciences Center, where they tour laboratories and clinics, help conduct experiments, and explore computer-based surgical simulations. The second unique program is a service learning project in which ninth-grade students assist with an activity that gives elementary school students a chance to participate in the process of scientific inquiry and to discover the wonder of real hearts and lungs; the ninth-graders assist with logistics (e.g., they distribute newspapers), and, more important, interact with the younger students by asking thoughtful questions of them. The partnership plans to incorporate the elementary and middle schools that graduate their students to Manual High School in order to encourage the implementation of inquiry-based science curricula and to provide sustained support to teachers throughout the entire K-12 educational pathway. If medical colleges can help teachers provide a consistent classroom draw for student fascination in science and medicine, then the colleges are more likely to help create a rich diversity of students who pursue careers in medicine.

Adolescent↗

PubMed2002

Fluoroscopy-based multiplanar image guidance for insertion of sacroiliac screws.

A prospective controlled experimental study was done to assess the value of fluoroscopy-based, computer-assisted orthopaedic surgery for the insertion of sacroiliac screws and to compare this new technology with the conventional technique, using image intensification. In a simulated surgical setup, 140 cannulated screws were placed into the S1 and S2 vertebral bodies of 35 pelvic models. The screws were inserted under fluoroscopy-based image guidance or with the conventional technique. Different drills were tested with both techniques, including a 2.8-mm guide wire and a 5-mm solid drill. The 2.8-mm guide wire proved inaccurate with the computer-assisted image guidance system because of guide wire flexibility. Using the more rigid 5-mm drill, the results of computer-assisted image guidance were comparable with the image intensifier technique. The radiation exposure during screw insertion was reduced considerably when using the image guidance system. System-specific requirements warranted adjustment of surgical technique and instruments. The major advantages of this new technology are immediate intraoperative image acquisition and provision of surgical guidance in as much as four planes simultaneously. The results of this experimental study are encouraging and have led to initiation of a clinical trial.

Bone Screws↗

PubMed1984

Traumatic partial parotidectomy.

A 16-year-old boy was assaulted with a broken bottle, which inflicted a deep right-sided cervicofacial injury. Exploration, however, revealed a split parotid gland along its plane of cleavage preserving the facial nerve and major cervical blood vessels with a unique traumatic dissection simulating surgical suprafacial parotidectomy.

Adolescent↗

PubMed1996

Neurosurgery and the Internet: a critical analysis and a review of available resources.

Thanks to the development of computers and telecommunication, the concept of communication is undergoing radical changes. Scientific collaboration among medical professionals has evolved rapidly in the last few years toward the use of Internet, a new tool which will change the world of health. It is impossible to predict at present where this new type of scientific collaboration will lead us, but what is certain is that in the next decade, the so-called electronic communities will be created and will develop at an extraordinary rate. The increase in the capacity of image processing in computers and in the rate of transmission of data over the net will make possible applications such as the remote medical visit, video conferences, surgical simulation or even remote virtual surgery. However, while some medical professionals are dreaming of this type of electronic communication in the future, others are using it right now, taking advantage of all of its benefits. In fact, electronic communities are already a reality, being accessible today, and not a future goal. Being inside or outside these communities will make the difference between health professionals. It is well worth therefore being in contact with these new fields so as not to miss the boat of technological development. We present a comprehensive listing of neurosurgical resources available on the Internet, and some ideas on the present and future applications of the Internet in the world of Health Care.

Computer Communication Networks↗

PubMed2001

The craniofacial anomalies archive at St. Louis Children's Hospital: 20 years of craniofacial imaging experience.

This article describes how the Craniofacial Imaging Laboratory at the Cleft Palate and Craniofacial Deformities Institute, St. Louis Children's Hospital, Washington University Medical Center, has developed an electronic archive for the storage of computed tomography image digital data that is independent of scanner hardware and independent of units of storage media (i.e., floppy disks and optical disks). The archive represents one of the largest repositories of high-quality computed tomography data of children with craniofacial deformities in the world. Archiving reconstructed image data is essential for comparative imaging, surgical simulation, quantitative analysis, and use with solid model fabrication (e.g., stereolithography). One tertiary craniofacial center's experience in the establishment and maintenance of such an archive through three generations of storage technology is reported. The current archive is housed on an external 35-GB hard drive attached to a Windows-based desktop server. Data in the archive were categorized by specific demographics into groups of patients, number of scans, and diagnoses. The Craniofacial Imaging Laboratory archive currently contains computed tomography image digital data for 1827 individual scans. The earliest scan was done in 1980; the most recently stored scan for the purposes of this report occurred in May of 2000. The average number of scans archived per complete year was 94, with a range of 59 to 138. Of the 1827 total scans, 74 percent could be classified into specific diagnostic categories. The majority of the archive (55 percent) is composed of the following five diagnoses: sagittal synostosis (17 percent), unilateral coronal synostosis (11 percent), hemifacial microsomia (10 percent), plagiocephaly without synostosis (10 percent), and metopic synostosis (7 percent). Storage of computed tomography image data in a digital archive currently allows for continuous upgrading of image display and analysis and facilitates longitudinal and cross-sectional studies, both intramural and extramural. Internet access for clinical and research purposes is feasible, but contingent on protection of patient confidentiality. The future of digital imaging regarding craniofacial computed tomography scan storage and processing is also discussed.

Child↗

PubMed1995

Instrumentation of the cervicothoracic junction after destabilization.

STUDY DESIGN: The biomechanics of three different instrumentation constructs applied at the destabilized cervicothoracic junction were evaluated. OBJECTIVES: To find an efficient way in restoring stability of the cervicothoracic junction in cases with and without laminectomy. SUMMARY OF BACKGROUND DATA: Different instrumentation techniques have been evaluated biomechanically and used clinically for managing instabilities between the fourth and sixth cervical vertebrae. These constructs have not been evaluated at the cervicothoracic junction. METHODS: Six human spines were tested nondestructively in axial torsion, flexion, and extension with the C6-T2 motion segments left unconstrained. The three-dimensional displacements and rotations between C7 and T1 vertebrae were measured using a sonic digitizer. After intact testing, a distractive-flexion Stage 3 cervical spinal injury was simulated surgically between C7 and T1. The specimens underwent sequential instrumentation and mechanical testing with three constructs: posterior Synthes lateral mass plate, posterior pediatric Cotrel-Dubousset rod system with lamina hooks and a crosslink, and anterior Synthes cervical locking plate. RESULTS: Posterior stabilization techniques had statistically more stiffness than anterior plates. The Cotrel-Dubousset system offered the largest stiffness ratio (instrumented/intact) in flexion, extension, and rotation. There was no statistical difference between posterior plates and Cotrel-Dubousset instrumentation. The stiffness of the anterior plate did not differ significantly from the intact spine. CONCLUSION: Our data show that instability of the cervicothoracic junction can be efficiently restored by either anterior plates, posterior plates, or posterior hook-rod constructs (Cotrel-Dubousset). Posterior constructs showed increased stiffness over anterior plates.

Aged↗

PubMed2006

Effect of lumbar interbody cage geometry on construct stability: a cadaveric study.

STUDY DESIGN: Biomechanical study to investigate three-dimensional motion behavior of cadaveric spines in various surgical simulations. OBJECTIVES: To determine the effect of cage geometry on the construct stability. SUMMARY OF BACKGROUND DATA: There is a wide variety of cage/spacer designs available for lumbar interbody fusion surgery. These range from circular, tapered, and rectangular with and without curvature. However, the effectiveness of cages with different designs and materials to stabilize a decompressed intervertebral space has not been fully studied. METHODS: Six fresh ligamentous lumbar spine specimens (L1-S2) were subjected to pure moments in the six loading directions. The resulting spatial orientations of the vertebrae were recorded using Optotrak Motion Measurement System. Measurements were made sequentially for intact, bilateral spacer placements across L4-L5 using a posterior approach, supplemented with pedicle screw-rod system fixation, and after the cyclic loading in flexion-extension mode. RESULTS: The stability tended to decrease after the bilateral cage placement as compared with the intact for all loading cases except flexion. In flexion, the angular displacement decreased to 80% of the intact. However, there was no significant statistical difference seen in stability between intact and after bilateral spacer placement. Following the addition of posterior fixation using pedicle screw-rod system, the stability significantly increased in all directions. Cyclic loading did not have any significant effect on the stability. CONCLUSIONS: Stand-alone cages restore motion to near-intact levels at best, and supplement instrumentation is essential for significantly increasing the stability of the decompressed segment. The effects of cage geometry and Young's modulus of the cage material do not seem to influence the stability, as compared with the other cagedesigns, especially after supplemental fixation with a posterior system.

Aged↗

PubMed2006

Guided tissue regeneration, barrier membranes and reconstruction of the cleft maxillary alveolus.

The use of barrier membranes for bone regeneration is especially beneficial in the case of severely affected soft tissue. One useful indication may be the formation of an effective shell for bone grafts in maxilla cleft defect reconstruction. When selecting a proper material for clinical use, one must consider the safety record, the resorption time and route of elimination, the time of the maintained barrier function, the necessary time of mechanical strength, and costs. Two resorbable collagen membranes, one of single-layer and one of double-layer material, were tested in vitro and in vivo. The tested single-layer membrane is less expensive, but it is also less handling than the double-layer membrane. In vitro, samples were incubated in simulated surgical wound. A complete unambiguous picture of disintegration was not proved histologically in either material in six investigation terms (1-6 weeks). In vivo the effect of the assessed membranes was verified on a group of patients (N = 45) with a cleft. Materials were applied in the reconstruction of the alveolar defect by cancellous bone grafts. The influence on the course of healing was not stated as statistically significant. However, with respect to the costs of double layer membrane, this material was used in the most severe cases.

Adolescent↗

PubMed2000

A 3-D reconstruction system for the human jaw using a sequence of optical images.

This paper presents a model-based vision system for dentistry that will assist in diagnosis, treatment planning, and surgical simulation. Dentistry requires an accurate three-dimensional (3-D) representation of the teeth and jaws for diagnostic and treatment purposes. The proposed integrated computer vision system constructs a 3-D model of the patient's dental occlusion using an intraoral video camera. A modified shape from shading (SFS) technique, using perspective projection and camera calibration, extracts the 3-D information from a sequence of two-dimensional (2-D) images of the jaw. Data fusion of range data and 3-D registration techniques develop the complete jaw model. Triangulation is then performed, and a solid 3-D model is reconstructed. The system performance is investigated using ground truth data, and the results show acceptable reconstruction accuracy.

Algorithms↗

PubMed2001

Computer-aided prototype system for nose surgery.

Rhinoplasty, or surgery to reshape the nose, is one of the most common of all plastic-surgery procedures. Rhinoplasty can enhance a patient's appearance and self-confidence, may also correct a birth defect or injury, or help relieve some breathing problem. In this paper, we present a three-dimensional (3-D) surgical simulation system, which can assist surgeons in planning rhinoplasty procedures. This system employs computer graphics and image-processing techniques for the simulation of a rhinoplasty. Although the presented algorithms themselves are not new, the proposed system exploits the new idea to apply 3-D morphing for rhinoplasty, and simulation results are useful for the physicians. According to patients' expectation of what they would like their noses to look like, our system simulates expected results. Our tools provide quantitative measurements of a nose structure. Using these quantitative results, surgeons can arrange appropriate preoperative plans for patients. Finally, experimental results and experiences are reported to evaluate the usefulness of the proposed system.

Computer Simulation↗

PubMed2004

Force modeling for needle insertion into soft tissue.

The modeling of forces during needle insertion into soft tissue is important for accurate surgical simulation, preoperative planning, and intelligent robotic assistance for percutaneous therapies. We present a force model for needle insertion and experimental procedures for acquiring data from ex vivo tissue to populate that model. Data were collected from bovine livers using a one-degree-of-freedom robot equipped with a load cell and needle attachment. computed tomography imaging was used to segment the needle insertion process into phases identifying different relative velocities between the needle and tissue. The data were measured and modeled in three parts: 1) capsule stiffness, a nonlinear spring model; 2) friction, a modified Karnopp model; and 3) cutting, a constant for a given tissue. In addition, we characterized the effects of needle diameter and tip type on insertion force using a silicone rubber phantom. In comparison to triangular and diamond tips, a bevel tip causes more needle bending and is more easily affected by tissue density variations. Forces for larger diameter needles are higher due to increased cutting and friction forces.

Animals↗

PubMed2006

In vivo mechanical behavior of intra-abdominal organs.

For realistic surgical simulation in a virtual environment, in vivo material properties of biological tissues are required for simulating the deformations and the reaction forces from the tool-tissue interactions. In this paper, the in vivo static and dynamic mechanical behavior of the liver and lower esophagus of pigs were presented both in linear and nonlinear regions under compressive and shear indentations. A robotic device was programmed to function as a mechanical stimulator with a 2-mm flat-tipped cylindrical probe attached to its tip. A series of ramp and hold stimuli, as well as sinusoidal indentation stimuli, were delivered to the organs and reaction forces were measured. The conditions for these indentation stimuli were designed such that they were similar to conditions in an operating room. Experiments were also carried out on the organs for ex vivo and in vitro conditions. Results show that the breathing and pulse rate significantly affect the measured force responses of the organs. From the obtained force-displacement relationships, steady-state impedances as well as dynamic impedances of both organs were calculated. The results also show that in vivo steady-state impedance of the lower esophagus is significantly higher than that of the liver. The in vivo steady-state response of the liver, however, exhibits a greater degree of nonlinearity than that of the lower esophagus. The in vivo steady-state response of the lower esophagus in the three orthogonal directions also indicates that the lower esophagus is not significantly anisotropic. The impedance of both organs under sinusoidal indentations (0-5 Hz) are fairly similar each other. Magnitudes of the impedance over the stimulus frequencies are fairly constant. The impedance phase angles decrease over the range of stimulus frequencies applied. Comparison of the measurements obtained from the in vivo, ex vivo, and in vitro experiments shows that the mechanical properties of the biological tissues change significantly after the death of the animal. The tissues generally become stiffer and exhibit greater nonlinearity. The degree of change in their mechanical properties is dependent on the amount of time after the death of the animal. These data can be further utilized in the computing of the material parameters of tissue models for laparoscopic surgery simulators as well as open surgery simulators.

Abdomen↗

PubMedDate not supplied

Automatic speech recognition in vitreo-retinal surgery. A project for a prototypal computer-based voice-controlled vitrectomy machine.

In the past half decade automatic speech recognition techniques, software and hardware technology have matured enough to support sophisticated medical applications. The project described aimed at introducing a computer-based, voice-controlled prototype system in a simulated vitreo-retinal surgery scenario. The aim was to provide the surgeon with a tool that could significantly improve the quality and ease of work and shorten the duration of intervention. The speech recognition system allows voice entry of simple commands to simulate surgical instrument control, including the infusion pump, vitreous cutter and diathermy. The project relies on a Markov-based, speaker-dependent, commercial isolated-word recognizer, and consists of a specific recognition vocabulary and application software, created and developed by the authors. Results have been encouraging. The system performed well under the test conditions, proving robust, simple to use and accurate (over 97% average word recognition rate). On the basis of their experience, the authors believe that automatic speech recognition technology, though suffering from some limitations such as the need for training, speaker dependence and a relatively small vocabulary, and requiring extensive testing under operating conditions, merits further development and opens new perspectives for a possible new generation of surgical instruments.

Artificial Intelligence↗