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Results for “Surgical simulation”

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At least 433 records · Page 24Linked to original sources

PubMed1994

Holmium: YAG laser surgery in obliterated cochleas: an experimental study in human cadaver temporal bones.

A pulsed holmium:YAG laser (lambda = 2120 nm) was used to reopen the basal turn of artificially obliterated human cochleas in freshly dissected cadavers. This allowed intracochlear insertion of the stimulation electrode of a cochlear implant under simulated surgical conditions. Laser energy was transmitted through a 400-microns nylon fiber via the opened facial recess directly to the round window niche. At an energy level of 500 mJ per 2.5 microseconds pulse, a repetition rate of 2 Hz, and an exposure time of 20-30 s, the photo-ablative mechanism of laser-bone interaction led to a 8-10 mm recanalization of the basal turn of the cochlea without damaging surrounding structures. The artificial bony occlusion and the recanalized basal turn of the cochlea were visualized by means of computed tomography and studied under light microscopy, using a histologic thin-section technique.

Aluminum Silicates↗

PubMed1991

Infrared laser stapedotomy.

A pulsed holmium: YAG laser (lambda = 1980 nm) was used to perform 0.4 mm stapedotomy fenestrations in human stapes footplates from freshly dissected cadavers under simulated surgical conditions. The energy was coupled into a 400 microns core diameter nylon fiber. Thermal gradients were then measured following laser applications and tissue responses examined by light microscopy. The results of this study suggest the feasibility of using a surgical holmium: YAG laser in middle ear surgery.

Humans↗

PubMed1999

Ergonomic problems associated with laparoscopic surgery.

BACKGROUND: The Society of American Gastrointestinal Endoscopic Surgeons (SAGES) Task Force on Ergonomics conducted a subjective and objective assessment of ergonomic problems associated with laparoscopic instrument use. The goal was to assess the prevalence, causes, and consequences of operational difficulties associated with the use of laparoscopic instruments. METHODS: A questionnaire was distributed asking respondents to rate the frequency with which they experienced pain, stiffness, or numbness in several body areas after laparoscopic operations. An ergonomics station was assembled to quantify forearm and thumb muscle workload. Processed electromyogram (EMG) signals were acquired from 27 volunteer surgeon subjects while they completed simulated surgical tasks using a hemostat and an Ethicon laparoscopic grasper, with the aid of an endoscopic trainer and video monitoring system. RESULTS: Of 149 surgeons responding to the questionnaire, 8% to 12% reported frequent pain in the neck and upper extremities associated with laparoscopic surgery. The ergonomics station demonstrated that the peak and total muscle effort of forearm and thumb muscles were significantly greater (p < 0.01) when the grasping task was performed using the laparoscopic instrument rather than the hemostat. CONCLUSION: These findings indicate that laparoscopic surgical technique is more taxing on the surgeon.

Cumulative Trauma Disorders↗

PubMed2000

[Telenavigation and expert consultation using a stereotaxic surgical videoserver].

The exponential increase of medical information creates a need for new methods in the visualization of medical imaging modalities for diagnosis and therapy. In this sense, visualization includes the display of medical image data and image-guided stereotaxic navigation as well as the advice of an expert. The Artma Virtual Patient System enables a remote expert to observe the surgical procedure via the Internet and interactively modify the interoperative visualization from the remote location. The expert in the remote location receives the planning data almost in real time over TCP/IP from a stereotaxic videoserver. In addition to live video streaming, stereotaxic navigation data are sent over the network as rigid body coordinates. The expert modifies the surgical simulation on the remote computer and the modified operating plan is sent back to the operating site. By teleconsulting, the composite images and overlapping graphics--instruments, target structures, landmarks, contour--can be seen in affiliated clinics with the possibility of interactive graphical assistance. With this image fusion technology the knowledge of a remote expert is included in virtual data structures and visualized by the overlay with live video data (augmented reality) in real time during surgery.

Humans↗

PubMed2001

[Comparative study of the quality of C-arm based 3D imaging of the talus].

Malposition of extraosseous or intra-articular screws, e.g., in osteosyntheses of joint fractures or in the vicinity of joints, frequently remains undiscovered in intraoperative fluoroscopy and is only recognized on postoperative computed tomography (CT) scans. The aim of the study, therefore, was to assess the value of a new mobile C-arm three-dimensional imaging device in comparison with fluoroscopy, conventional radiographs, and CT scans using an extremity model. Screws were inserted ventrally in four anatomic lower leg specimens without talus fractures parallel to the longitudinal axis to simulate surgical management of fractures of the talus. The specimens supplied were examined with fluorscopy, conventional radiography, spiral CT, and the new three-dimensional imaging with the SIREMOBIL Iso-C3D. These four modalities were evaluated by ten radiologists and ten trauma surgeons and were compared regarding subjective image quality and position of the screws. The quality of information acquired with the SIREMOBIL Iso-C3D was equal to that of the CT examinations, although image quality was considered inferior to fluoroscopy, conventional radiography, and CT (p < 0.001). In contrast to the previous procedure with intraoperative fluoroscopy and subsequent postoperative X-ray control, the results obtained with the SIREMOBIL IsoC3D were superior. The SIREMOBIL Iso-C3D is useful for the intraoperative diagnosis of small joints with few artifacts producing osteosynthesis material, i.e., for recognizing the position of screws in the region of glenoid surfaces.

Bone Screws↗

PubMed2002

Acetabular roof reconstruction with pedicled iliac graft.

Reconstruction of the acetabular roof in patients with hip dysplasia shows disappointing mid-term results due to insufficient incorporation and collapse of the bone graft. We have developed a new reconstructive method using a pedicled iliac graft. We simulated surgical reconstruction of the acetabular roof in ten cadaver specimens. The purpose was to evaluate whether the deep circumflex artery was long enough to allow transfer of the graft without requiring micro-vascular anastomosis. In all cadavers, the length of the pedicle was sufficient to reach any desired position of the acetabular roof. The use of such a pedicled structural graft may provide good primary stability and allow local bony remodelling and incorporation under load.

Acetabulum↗

PubMed2000

Puncture forces of solid organ surfaces.

BACKGROUND: In this experimental study, we measured the force needed to puncture the liver (low elastin) and the spleen (high elastin). The surface displacement preceding puncture was also measured. These data are relevant to an understanding of surgical technique and are essential to the development of electronic surgical simulators. METHODS: Controlled puncture experiments were performed on intact organs harvested from pigs and sheep, as well as on their surface capsules following removal and suspension at zero strain and at three increasing levels of prestrain. The biomechanical data were compared with information obtained from histological studies. RESULTS: The spleen has a higher puncture force than the liver and suffers greater displacement before puncture (p < 0.05). Prestrain decreases displacement before puncture (p < 0.05) but has no effect on puncture force. CONCLUSION: The higher puncture force and displacement of spleen, as compared with liver, is probably due to its higher elastin content.

Animals↗

PubMed2001

Automated high-frequency posture sampling for ergonomic assessment of laparoscopic surgery.

BACKGROUND: Despite widespread acknowledgement that strain injuries do occur to surgeons, ergonomic assessments in minimally invasive surgery are comparatively rare. Current assessment techniques rely on labor-intensive manual recording techniques, so there is a need for an automated system. METHODS: We used an optoelectronic measurement system to make postural measurements at frequencies of ~5 Hz and then converted these measurements to ergonomic stress scores using a modified Rapid Upper Limb Assessment (RULA) method. RESULTS: We successfully recorded postures at least once per second during 96% of the time the surgeon was performing tissue manipulation tasks. We found that the ergonomic stress scores were comparatively high throughout the procedure, particularly for the wrist. CONCLUSION: An automated high-frequency postural measurement system is feasible for making ergonomic assessments in an intraoperative setting. Such a system will also be a critical component in validating surgical simulations for use in training and credentialing surgeons and in designing and evaluating equipment.

Biomechanical Phenomena↗

PubMed2004

Biomechanics of cervical laminoplasty: kinetic studies comparing different surgical techniques, temporal effects and the degree of level involvement.

Laminoplasty is a common surgical technique used to treat cervical myelopathy. Both voids and contradictory information exist in the literature with regard to the initial and long-term biomechanical consequences of cervical laminoplasty. In order to clarify the existing literature, as well as provide clinically useful information, we identified three specific aims: (1) to measure the long-term differences in kinetics between the open door laminoplasty (ODL) and French door laminoplasty (FDL) techniques; (2) to delineate differences in primary and long-term cervical motion after laminoplasty; and (3) to determine whether inclusion of additional levels in the laminoplasty procedure results in a change in immediate cervical biomechanics. The study design involved both an animal (caprine) model and in vitro surgical simulation. We kinematically evaluated the cervical spine specimens (C2-C7) by applying pure bending moment loads to the cephalad vertebra (C2), while constraining the caudal vertebra (C7). Resultant intervertebral rotations (C3-C6) were determined via stereophotogrammetry. Overall, the data indicate that both FDL and ODL significantly reduce range of motion 6 months postoperatively, compared with the un-operated spine. There were no significant differences between the two techniques after 6 months. We also showed that ODL produces a significant reduction in motion 6 months postoperatively compared with the immediate postoperative condition. Finally, the data indicated that extending the laminoplasty from two to four levels did not significantly change range of motion. The choice of technique should be based upon the surgeon's experience with these technically demanding procedures. In addition, initial stability considerations should not affect the decision to extend the laminoplasty to adjacent levels. Finally, the data also suggest that early changes in biomechanics should not be a major factor when considering whether immobilization of the cervical spine is necessary after laminoplasty. In fact, our temporal study, as well as previously reported clinical data, indicates that one should expect significantly decreased intervertebral motion 6 months after laminoplasty. Therefore, early physical therapy should be considered to preserve a more physiologic pattern of cervical range of motion.

Animals↗

PubMed2005

An anatomically based patient-specific finite element model of patella articulation: towards a diagnostic tool.

A 3D anatomically based patient-specific finite element (FE) model of patello-femoral (PF) articulation is presented to analyse the main features of patella biomechanics, namely, patella tracking (kinematics), quadriceps extensor forces, surface contact and internal patella stresses. The generic geometries are a subset from the model database of the International Union of Physiological Sciences (IUPS) (http://www.physiome.org.nz) Physiome Project with soft tissue derived from the widely used visible human dataset, and the bones digitised from an anatomically accurate physical model with muscle attachment information. The models are customised to patient magnetic resonance images using a variant of free-form deformation, called 'host-mesh' fitting. The continuum was solved using the governing equation of finite elasticity, with the multibody problem coupled through contact mechanics. Additional constraints such as tissue incompressibility are also imposed. Passive material properties are taken from the literature and implemented for deformable tissue with a non-linear micro-structurally based constitutive law. Bone and cartilage are implemented using a 'St-Venant Kirchoff' model suitable for rigid body rotations. The surface fibre directions have been estimated from anatomy images of cadaver muscle dissections and active muscle contraction was based on a steady-state calcium-tension relation. The 3D continuum model of muscle, tendon and bone is compared with experimental results from the literature, and surgical simulations performed to illustrate its clinical assessment capabilities (a Maquet procedure for reducing patella stresses and a vastus lateralis release for a bipartite patella). Finally, the model limitations, issues and future improvements are discussed.

Computer Simulation↗

PubMed1996

Salvage of ischemic myocardium with simplified and even delayed coronary sinus retroperfusion.

BACKGROUND: Despite the proven efficacy of pressure-controlled intermittent coronary sinus obstruction (PICSO) and synchronized retrograde perfusion (SRP) in salvaging ischemic myocardium, wide application of these coronary sinus (CS) retroperfusion techniques has been limited by concerns about their safety and complexity and in particular the need for repeated occlusion of the CS with a balloon. To address these concerns a simplified retroperfusion technique (SR) was developed that continuously infuses superior vena caval blood at 7 mL/min into the CS catheter without balloon occlusion. METHODS: Thirty pigs underwent 90 minutes of ischemia imposed by snaring the two largest diagonal branches of the left anterior descending artery and were randomized to one of five treatment groups: One group received no retroperfusion (control). Three groups had immediate (Im) institution of PICSO, SRP, or SR. In a final group, an initial 60 minutes of ischemia was followed by 30 minutes of delayed SR with superior vena caval blood. All animals were then placed on cardiopulmonary bypass and, after a 60-minute cardioplegic arrest, the coronary artery obstructions were removed, to simulate surgical revascularization. This was followed by 3 hours of reperfusion. The area of myocardium at risk and the area of infarction were determined by methylene blue and triphenyltetrazolium chloride staining with planimetric quantification. RESULTS: Results are reported as mean +/- standard deviation. The area of the left ventricle at risk for infarction was similar in all the treatment groups and represented 22.3% +/- 4.1% of the left ventricular mass. The area of infarction after 3 hours of reperfusion was 48.5% +/- 11.0% for the control group, 26.8% +/- 7.3% for Im-PICSO, 24.9% +/- 4.8% for Im-SRP, 22.4% +/- 6.6% for Im-SR, and 27.7% +/- 7.2% for delayed SR (p < 0.01 for each group versus control). The mean CS pressure (in mm Hg) during treatment was 6.3 +/- 1.7 for the control group, 25.7 +/- 4.5 for Im-PICSO, 22.8 +/- 3.7 for Im-SRP, 5.0 +/- 1.5 for Im-SR, and 6.3 +/- 2.1 for delayed SR (p < 0.01 for Im-PICSO and Im-SRP versus control). CONCLUSIONS: The simplified retroperfusion technique is as effective as PICSO and SRP in salvaging ischemic myocardium, but is considerably simpler. The simplified retroperfusion technique is inherently safer because of the lower CS pressures imposed by low flows and the lack of CS balloon obstruction. The efficacy of delayed SR has profound implications on possible mechanisms of ischemic myocardial salvage. Further investigation is warranted.

Animals↗

PubMed1993

Mandibular lengthening by gradual distraction: analysis using accurate skull replicas.

Bone lengthening in the upper and lower extremities by gradual distraction has become an accepted procedure. We have used an extraoral device to lengthen the mandible in four patients with unilateral mandibular hypoplasia. Using an accurate skull replica, the proposed corticotomy line, intended direction of lengthening, and appropriate position for the screws were determined. Following distraction, a significant increase in the dimensions of the affected mandible was obtained in each case. In this series, accurate skull replicas proved very useful for defining the anatomy, for surgical simulation and for pre- and postoperative evaluation.

Adolescent↗

PubMed1990

Neurofibroma of the ovary.

We report an unusual example of ovarian neurofibroma in a woman with neurofibromatosis (von Recklinghausen's disease). The neoplasm caused ovarian enlargement which surgically simulated malignant neoplasm. Ovarian neurofibromas are extremely rare and may arise from small myelinated nerves in the ovarian hilum.

Female↗

PubMed1993

Measurement of carpal bone geometry by computer analysis of three-dimensional CT images.

The aim of this project was noninvasively to analyze and quantitate the geometry, load transfer characteristics, and spatial relationships of the carpal bones by using a new three-dimensional CT scan reconstruction technique. The determination of mechanical parameters such as distances between centroids and between bone surfaces, carpal alignment, volumes, surface areas, and contact areas can provide the basis for comparison between normal wrists and wrists with a variety of progressive instability patterns, types of fracture, pathologic and posttraumatic states, and different simulated surgical procedures. This new technology has demonstrated a volumetric accuracy of 94% and a linear accuracy of 97%. Simultaneous analysis of all articulating surfaces of multiple joints can be performed in cadavers and in patients because of the noninvasive nature of the imaging reconstruction technique. This new research offers much more information than has previously been available. It also promises direct application to the clinical setting and eliminates several limitations and questions that were inescapable with previous technology.

Adult↗

PubMed2006

Computerized estimation of the lung volume removed during lung volume reduction surgery.

RATIONALE AND OBJECTIVES: This study was designed to develop an automated method for estimating lung volume removed during lung volume reduction surgery (LVRS) using computed tomography (CT). MATERIALS AND METHODS: The CT examinations of six patients who underwent bilateral LVRS were analyzed in this study. The resected lung tissue (right and left) was weighed during pathologic examination. An automated computer scheme was developed to estimate the lung volume removed using the CT voxel values and lung specimen weight. The computed fraction of lung volume removed was evaluated across a range of simulated surgical planes (ie, other than parallel to the CT image plane) and CT reconstruction kernels, and it was compared with the surgeons' postsurgical estimates. RESULTS: The computed fraction of the lung volume removed during LVRS was linearly correlated with the resected lung tissue weight (Pearson correlation = 0.697, P = .012). The computed fraction of lung volume removed ranged from 12.9% to 51.7% of the total lung volume. The surgeons' postsurgical estimates of lung volume removed ranged from 30% to 33%. The percent difference between the surgeons' estimates and the computed lung volume removed as a percentage of the surgeons' estimates ranged from -72.3% to 57.0% with mean absolute difference of 29.7% (+/-20.7). CONCLUSION: The preliminary findings of this study suggest that the proposed quantitative model should provide an objective measure of lung volume removed during LVRS that may be used to investigate the relationship between lung volume removed and outcome.

Absorptiometry, Photon↗

PubMed2004

Biomechanics in uniaxial compression of three distal radius volar plates.

PURPOSE: A new fixed-angle volar plate for a dorsally displaced distal radius fracture was designed with the aim of avoiding soft tissue problems due to dorsal plating. The purpose of this study was to compare the biomechanical properties of this new plate with 2 existing volar plates in a cadaver model. METHODS: Three different plates were applied on surgically simulated unstable extra-articular distal radius fractures in formalin-fixed cadaver radiuses. Group 1 (volarly placed AO titanium Distal Radius plates [Synthes Ltd, Paoli, PA]; n = 6), group 2 (volarly placed titanium Symmetry plates [DePuy ACE Co, El Segundo, CA]; n = 6), and group 3 (volarly placed newly designed titanium plates; n = 6) were tested to failure under axial compression with a materials testing machine. Specimens of all 3 groups had similar bone mineral density. RESULTS: Group 3 specimens had significantly greater elastic limit and ultimate strength than the other 2 groups. Specimens of group 3 had the greatest rigidity, although this was statistically insignificant compared with the other 2 groups. All plates (groups 1, 2, 3) failed in apex volar angulation. CONCLUSIONS: The newly designed plate fixation system is the strongest of the systems tested and may offer adequate stability for the treatment of a distal radius fracture in which the dorsal and/or volar metaphyseal cortex is comminuted severely.

Aged↗

PubMed2006

An in vitro analysis of ligament reconstruction or extension osteotomy on trapeziometacarpal joint stability and contact area.

PURPOSE: Painful instability of the minimally osteoarthritic thumb carpometacarpal (CMC) joint can be treated successfully by either ligament reconstruction or metacarpal extension osteotomy. The purpose of this study was to measure the laxity of cadaveric thumb CMC joints and to determine the influence of ligament reconstruction and metacarpal osteotomy on joint laxity and contact area. METHODS: The baseline laxity of CMC joints from 25 fresh-frozen human cadaveric specimens (average age, 42 y; range, 18-55 y) was measured in the position of lateral pinch on a custom-designed CMC joint laxity tester. Joint laxity was measured again after 2 surgical simulations consisting of either a metacarpal extension osteotomy (at 10 degrees and 15 degrees) or a simulated Eaton-Littler ligament reconstruction (including total, volar, and dorsal ligament reconstructions relative to the plane of the thumbnail). Contact area between the thumb metacarpal and trapezium during testing was determined using stereophotogrammetry. RESULTS: The 15 degrees extension osteotomy significantly reduced CMC joint laxity in the radial-ulnar, dorsal-volar, pronation-supination, and distraction directions in the position of lateral pinch. The 10 degrees osteotomy reduced laxity only in the dorsal-volar direction. The total ligament reconstruction significantly reduced joint laxity in the radial-ulnar, dorsal-volar, and pronation-supination directions. The dorsal ligament reconstruction reduced laxity in the dorsal-volar direction only; the volar ligament reconstruction reduced laxity in both dorsovolar and radioulnar directions. The 10 degrees and 15 degrees osteotomies produced a dorsal shift of the weighted centroid of contact on the metacarpal and trapezium, whereas the ligament reconstruction did not produce such an effect. CONCLUSIONS: In the position of lateral pinch the 15 degrees osteotomy and total ligament reconstruction significantly reduced laxity of the thumb CMC joint in all directions tested. The isolated dorsal or volar ligament reconstructions both reduced dorsal-volar laxity. Metacarpal extension osteotomy may stabilize the thumb CMC joint in lateral pinch to a degree similar to that of a standard ligament reconstruction.

Adolescent↗

PubMed2005

An ergonomic comparison of robotic and laparoscopic technique: the influence of surgeon experience and task complexity.

BACKGROUND: This study compares the mental and physical workload of laparoscopic and robotic technique while performing simulated surgical tasks in a laboratory setting. MATERIALS AND METHODS: Ten volunteer surgeons performed two tasks in a laparoscopic trainer using laparoscopic (LAP) and robotic (ROB) techniques. Outcome measures included: Task time, task-error, vertical/horizontal arm displacement, percent maximum electromyographic signal from the thenar, forearm flexor, and deltoid muscle compartments, skin conductance, and perceived difficulty and discomfort levels. A two-way repeated-measures ANOVA compared surgical technique and laparoscopic experience level (E = expert, N = novice). RESULTS: For the simple task, ROB technique was slower and had higher errors, and the surgeon's arm was more elevated. For the complex task, ROB electromyographic signal was lower. Stress was lower in both tasks for ROB, but the decrease was not statistically significant. CONCLUSIONS: Robotic technique appears slower and less precise than laparoscopic technique for simple tasks, but equally fast and possibly less stressful for complex tasks. Previous laparoscopic experience has a complex influence on the physical and mental adaptation to robotic surgery.

Adult↗