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PubMedDate not supplied

Evaluation of video tape and a simulator for instruction of basic surgical skills.

Twenty first-year veterinary students with no prior participatory experience in surgery were randomly paired and assigned into two study groups. Ten students (group V) viewed a hemostatic technique video tape until they thought they could competently perform and assist in performing a hand-tied ligature on a blood vessel in a live animal. Ten students (group VS) wer also given a simulator for technique practice. Paired students were video recorded and blindly evaluated on their ability to perform and assist proper ligation of a bleeding vessel. Inexpensive hemostasis models were very helpful for teaching students essential surgeon and assistant skills involved in hand-tied ligature placement. Students who practiced with simulators performed significantly better as surgeon and assistant, and in total psychomotor skill evaluation, then students watching the video only. Students using simulators performed ligation with significantly more accuracy and tended to be more expeditious at this task. Further training is needed for students to acquire skills necessary for efficient bleeding vessel exposure and isolation.

Animals↗

PubMed1998

Validation of virtual reality to teach and assess psychomotor skills in laparoscopic surgery: results from randomised controlled studies using the MIST VR laparoscopic simulator.

Objective assessment of surgical technique is currently impossible. A virtual reality simulator for laparoscopic surgery (MIST VR) models the movements needed to perform minimally invasive surgery and can generate a score for various aspects of psychomotor skill. Two studies were performed using the simulator: first to assess surgeons of different surgical experience to validate the scoring system; second to assess in a randomised controlled way, the effect of a standard laparoscopic surgery training course. Experienced surgeons (> 100 laparoscopic cholecystectomies) were significantly more efficient, made less correctional submovements and completed the virtual reality tasks faster than trainee surgeons or non-surgeons. The training course caused an improvement in efficiency and a reduction in errors, without a significant increase in speed when compared with the control group. The MIST VR simulator can objectively assess a number of desirable qualities in laparoscopic surgery, and can distinguish between experienced and novice surgeons. We have also quantified the beneficial effect of a structured training course on psychomotor skill acquisition.

Cholecystectomy↗

PubMed1988

Dual-detector probe for surgical tumor staging.

A hand-held, dual-detector probe has been developed for surgical tumor staging. This dual probe simultaneously monitors counts from a possible tumor site along with counts from adjacent normal tissue using two concentric, collimated scintillation detectors. A comparison of counts from the detectors can distinguish a small tumor directly in front of the probe from variations in background activity. The probe was tested in computer simulations of surgical staging of metastases to para-aortic and iliac lymph nodes using a spatial response map of the probe, a numerical torso phantom, and organ activity data for [57Co]bleomycin in rabbits. Results show that the dual probe performs better than a single-detector probe in detecting tumors and solves the problem caused by spatial variations in the background source distribution.

Computer Simulation↗

PubMed2004

[Limitations of orthognathic model surgery: theoretical and practical implications].

Orthognathic model surgery is a classical technique used to simulate orthognathic surgical cases. However, a detailed analysis of this technique demonstrates that theoretical errors and inaccuracies can occur in routine practice. 2D and 3D cephalometric analysis is the first source of inaccuracies. Then, during the occlusal plane transfer from the patient to the semi-adjustable dental articulator, errors can occur by inaccurate manipulation of the facial bow. Simulating the operation on the plaster cast is difficult due to the lack of a real link between the cephalometric analysis and the model surgery. Rotation and translation movements of the plaster casts are insufficiently controlled during the model surgery stage. Finally, the splint, which transfers the final relative position of maxilla to the mandible, summates all of the errors of the previous stages.

Cephalometry↗

PubMed1999

Fluoroscopy as an imaging means for computer-assisted surgical navigation.

OBJECTIVE: Intraoperative fluoroscopy is a valuable tool for visualizing underlying bone and surgical tool positions in orthopedic procedures. Disadvantages of this technology include the need for continued radiation exposure for visual control, and cumbersome means of alignment. The purpose of this article was to highlight a new concept for a computer-assisted freehand navigation system that uses single intraoperatively acquired fluoroscopic images as a basis for real-time navigation of surgical tools. MATERIALS AND METHODS: Optoelectronic markers are placed on surgical tools, a patient reference, and the fluoroscope to track their position in space. Projection properties of the fluoroscope are acquired through an initial precalibration procedure using a tracked radiopaque phantom grid. Corrections are applied to compensate for both the fluoroscope's image intensifier distortions and the mechanical bending of the C-arm frame. This enables real-time simulation of surgical tool positions simultaneously in several single-shot fluoroscopic images. In addition, through optoelectronically tracked digitization of a target viewpoint, the fluoroscope can be numerically aligned at precise angles relative to the patient without any X-ray exposure. RESULTS: This article shows the feasibility of this technology through its use in cadaver trials to perform the difficult task of distal locking of femoral nails.

Bone Nails↗

PubMed1999

Haemorrhage into non-functioning adrenal cysts--report of two cases and review of the literature.

Adrenal cysts are a rare condition and are usually non-functioning and asymptomatic. Most of the reported cases were incidental findings or discovered at autopsy. However, large cysts have a tendency to develop complications such as intracystic haemorrhage and rupture, which can present as an acute surgical emergency. We report two cases of adrenal cysts with intracystic haemorrhage. One patient presented with persistent non-specific upper abdominal pain, investigations with ultrasound (US) scan and computed tomographic (CT) scan revealed a left adrenal cyst and gallstones. Simultaneous cholecystectomy and adrenalectomy was performed with resultant relief of symptoms. The second patient presented with acute abdominal pain simulating acute surgical abdomen. Preoperative CT scan showed a large cystic lesion in the region of the tail of the pancreas with radiological evidence of haemorrhage but was unable to confirm its origin. The cyst was found to have arisen from the left adrenal gland at laparotomy; left adrenalectomy with complete excision of the cyst was done. Histology showed pseudocyst with haemorrhage in both cases. Pseudocyst is the commonest histological type encountered clinically. We believe the second case is related to pregnancy and childbirth as the patient presented during puerperium and the cyst, even though very large in size (25 x 15 x 15 cm), was not noted during antenatal screening with US scan.

Adrenal Gland Diseases↗

PubMed1996

Evaluation of ion-implanted-silicon detectors for use in intraoperative positron-sensitive probes.

The continuing development of probes for use with beta (positron and electron) emitting radionuclides may result in more complete excision of tracer-avid tumors. Perhaps one of the most promising radiopharmaceuticals for this task is 18F-labeled-Fluoro-2-Deoxy-D-Glucose (FDG). This positron-emitting agent has been demonstrated to be avidly and rapidly absorbed by many human cancers. We have investigated the use of ion-implanted-silicon detectors in intraoperative positron-sensitive surgical probes for use with FDG. These detectors possess very high positron detection efficiency, while the efficiency for 511 keV photon detection is low. The spatial resolution, as well as positron and annihilation photon detection sensitivity, of an ion-implanted-silicon detector used with 18F was measured at several energy thresholds. In addition, the ability of the device to detect the presence of relatively small amounts of FDG during surgery was evaluated by simulating a surgical field in which some tumor was left intact following lesion excision. The performance of the ion-implanted-silicon detector was compared to the operating characteristics of a positron-sensitive surgical probe which utilizes plastic scintillator. In all areas of performance the ion-implanted-silicon detector proved superior to the plastic scintillator-based probe. At an energy threshold of 14 keV positron sensitivity measured for the ion-implanted-silicon detector was 101.3 cps/kBq, photon sensitivity was 7.4 cps/kBq. In addition, spatial resolution was found to be relatively unaffected by the presence of distant sources of annihilation photon flux. Finally, the detector was demonstrated to be able to localize small amounts of FDG in a simulated tumor bed; indicating that this device has promise as a probe to aid in FDG-guided surgery.

Beta Particles↗

PubMed1997

[Immediate and late outcomes of surgical treatment in patients with tumor-simulating pulmonary tuberculosis].

The specific features and outcomes of surgical treatment were analyzed in 122 newly detected patients with pulmonary tuberculomas without prior specific therapy. Postoperative complications developed in 4.1% of the patients undergone surgery, recurrent tuberculosis was observed in 1.6%. Early surgical interventions in this group of patients were found to reduce the time of treatment and working rehabilitation. A value of intraoperative rapid cytological verification of diagnosis was shown while choosing the adequate volume of lung resection in difficult diagnostic cases.

Adolescent↗

PubMed2004

[Subcutaneous dirofilariasis due to Dirofilaria repens in Tunisia: a case involving the scrotum].

Dirofilariasis is a rare anthroponotic disease encountered only in the old world with most cases having been reported from Italy. The dog is the reservoir of this parasite. Man is accidentally infected by mosquitoes. We report the case involving a 27-year-old man living in a rural region of northern Tunisia who presented with a subcutaneous abscess-like scrotal nodule. Microscopic examination of the surgical specimen unexpectedly revealed parasitic involvement. Morphologic examination led to diagnosis of subcutaneous dirofilariasis due to Dirofilaria repens. This case of subcutaneous dirofilariasis brings the total number of cases reported in Tunisia to 6 and is a reminder that this parasitic disease is present in our country and that its incidence is probably underestimated. The scrotum is a rare location that poses the problem of differential diagnosis with malignant tumor or can simulate a surgical emergency. Excision allows diagnosis and treatment.

Adult↗

PubMed1996

Virtual Reality Hysteroscopy

New interactive computer technologies are having a significant influence on medical education, training, and practice. The newest innovation in computer technology, virtual reality, allows an individual to be immersed in a dynamic computer-generated, three-dimensional environment and can provide realistic simulations of surgical procedures. A new virtual reality hysteroscope passes through a sensing device that synchronizes movements with a three-dimensional model of a uterus. Force feedback is incorporated into this model, so the user actually experiences the collision of an instrument against the uterine wall or the sensation of the resistance or drag of a resectoscope as it cuts through a myoma in a virtual environment. A variety of intrauterine pathologies and procedures are simulated, including hyperplasia, cancer, resection of a uterine septum, polyp, or myoma, and endometrial ablation. This technology will be incorporated into comprehensive training programs that will objectively assess hand-eye coordination and procedural skills. It is possible that by incorporating virtual reality into hysteroscopic training programs, a decrease in the learning curve and the number of complications presently associated with the procedures may be realized. Prospective studies are required to assess these potential benefits.

Journal Article↗

PubMed2001

Atrial size reduction as a predictor of the success of radiofrequency maze procedure for chronic atrial fibrillation in patients undergoing concomitant valvular surgery.

INTRODUCTION: Previous studies showed that the surgical maze procedure can restore sinus rhythm and atrial transport function in patients with chronic atrial fibrillation (AF). However, no previous studies discussed the association of atrial size reduction and the success of sinus conversion by the radiofrequency (RF) maze procedure for chronic AF. METHODS AND RESULTS: A total of 119 chronic AF patients undergoing valvular operations were included in this study. Sixty-one patients received RF and cryoablation to create lesions in both atria to simulate the surgical maze II or III procedure (RF maze II or RF maze III; 13 patients, group 1) or a modified maze pattern (RF maze "IV"; 48 patients, group 2). The other 58 patients who underwent valvular operations alone without the maze procedure served as control (group 3). At 3-month follow-up after operation, sinus rhythm was restored in 73%, 81%, and 11% of patients in groups 1, 2 and 3, respectively. Preoperative left and right atrial sizes were not statistically significant predictors of sinus conversion by the RF maze procedure. However, as a result of postoperative reduction of atrial sizes, postoperative left atrial diameter was significantly smaller in patients who had sinus conversion by the RF maze procedure than in patients who did not regain sinus rhythm (45.0+/-7.0 mm vs 51.0+/-8.0 mm; P = 0.03). Postoperative right atrial area of patients who had sinus conversion by the RF maze procedure also was significantly smaller than that of patients who did not regain sinus rhythm (18.1+/-4.4 cm2 vs 28.5+/-8.2 cm2; P = 0.008). CONCLUSION: Atrial size reduction appears to predict the success of sinus conversion with the RF maze procedure used in conjunction with valvular surgery.

Adult↗

PubMed1998

Generating finite element models from volumetric medical images.

For planning and simulating of surgical interventions geometric models have to be generated from medical images. In this paper, we will present a new method for generating finite element meshes from volumetric images. The method is designed to capture even very small anatomic structures, while the mesh density can be controlled and locally increased.

Algorithms↗

PubMed1989

[Bone drilling simulation by three-dimensional imaging].

The three-dimensional display technique has a wide range of medical applications. Pre-operative planning is one typical application: in orthopedic surgery, three-dimensional image processing has been used very successfully. We have employed this technique in pre-operative planning for orthopedic surgery, and have developed a simulation system for bone-drilling. Positive results were obtained by pre-operative rehearsal; when a region of interest is indicated by means of a mouse on the three-dimensional image displayed on the CRT, the corresponding region appears on the slice image which is displayed simultaneously. Consequently, the status of the bone-drilling is constantly monitored. In developing this system, we have placed emphasis on the quality of the reconstructed three-dimensional images, on fast processing, and on the easy operation of the surgical planning simulation.

Computer Simulation↗

PubMed1997

2D and 3D finite element pre- and post-processing in orthopaedy.

The present widespread tomographic techniques based on computed tomography (CT), magnetic resonance imaging (MRI) and automatic 2D and 3D reconstructions also involve numerous new points of view for planning surgical techniques in orthopaedy. These require efficient pre- and post-processing methods. By pre-processing and post-processing is meant both the generation of a finite element mesh that numerically models human joints and the visualization of the results obtained as required by the surgeon. Since the numerical reconstructions of human joints are based on the finite element approximation of contact problems assuming linear elasticity, the main goal of pre-processing is to generate triangular (2D) and tetrahedral (3D) meshes of objects with a 'reasonable' boundary-human joints. In our paper we restrict ourselves, for the sake of simplicity, to polygonal (resp. polyhedral) objects. The idea of preprocessing is based on the modified method of Delaunay Mangulalia and on the so-called relaxation technique. After the generation of the finite element mesh and after numerical simulation of surgical problems of orthopaedy, the results obtained as stress-strain fields, temperature, etc. may be visualized in a graphical form on the computer screen as well as on other media.

Arthrography↗

PubMedDate not supplied

[Experimental and clinical substantiation of the functional transpedicular stabilization of the vertebral column].

Metallic construction for transpecular stabilization (transpedicular constructions T-TPC). Titanium nickelide (TiNi) alloys have come into existence in the surgical treatment of diseases of the vertebral column and spinal cord. The properties of these alloys are the storage of a shape, superelasticity, and cyclic longevity. The adequate mechanical behavior of live tissues and TiNi-based alloys suggests that metallic constructions made from TiNi are more physiological and functional than those made from steels and titanium alloys. The foregoing makes it possible to consider the design of metallic constructions to be promising for transpedicular spinal stabilization involving the latter's reliability and stability with the physiological and functional capacities of TiNi fixing arms. The study performed computer-assisted simulation of surgical treatment for different spinal diseases by using TPC by means of the programme package ANSYS and statistical and cyclic studies of TPC up to the international standards on a Terotest testing machine. The experimental findings were used to formulate recommendation to use TPC of varying rigidity to treat spinal injuries and diseases. Eight operations were performed to treat patients with diseases of the lower thoracic and lumbar parts of the vertebral column, by using TiNi rod of the optimum rigidity, which yielded good clinical results.

Equipment Design↗

PubMed1990

[Ultrasound instruments for surgical purposes--technical aspects and selected areas for use].

Surgical instruments simulated to oscillate by means of low-frequency performance ultrasound are particularly useful for specific fields of application. A survey describes the technical principle of action and the development work carried out at the Technical University of Karl-Marx-Stadt in the GDR to produce ultrasound instruments for tumour extraction and aspiration, for the insertion of stomatological leaf implants, for percutaneous lithotrips of kidney stones and for the surface treatment of septic wounds.

Blade Implantation↗

PubMed2005

Reloading the heart: a new animal model of left ventricular assist device removal.

OBJECTIVES: Left ventricular assist devices are proposed as a bridge to recovery, but recurrent ventricular deterioration has limited this approach. We describe a new animal model that simulates the effects of left ventricular assist device unloading and then reloading after device removal. The model might facilitate the evaluation of interventions intended to prevent recurrent ventricular dysfunction. METHODS: The hearts and lungs of Lewis rats were removed and transplanted into the abdomen of recipient rats by anastomosing the donor's ascending aorta to the recipient's abdominal aorta. The transplanted hearts were maintained unloaded for 2 weeks in 49 animals. Eighteen transplanted hearts were removed after 2 weeks of unloading. In 17 animals the donor's right pulmonary artery was anastomosed to the recipient's abdominal aorta to reload the heart for an additional 2 weeks. In 14 animals the hearts were maintained unloaded for 4 weeks (an additional 2 weeks). The unloaded and reloaded hearts were compared with normal rat hearts (n = 18). RESULTS: In the unloaded hearts the left ventricular end-diastolic pressures remained low. The left ventricular systolic pressures were lower than the aortic pressures. The left ventricular weights (n = 8) and volumes (n = 4) remained significantly lower ( P < .01) than in the normal hearts. Two weeks after reloading, the left ventricular end-diastolic pressure (n = 8) increased ( P < .01), and the ventricle ejected. The left ventricular systolic pressures exceeded the aortic pressures. The left ventricular weights and volumes increased ( P < .01) and approached those of normal hearts. Matrix metalloproteinase 9 (n = 6/group) levels decreased in the unloaded state ( P = .02) and increased back to normal values after reloading. CONCLUSIONS: This surgical model simulated left ventricular assist device unloading of the left ventricle. The second operation reloaded the left ventricle, which then enlarged. This model will permit the evaluation of adjunctive interventions, such as cell transplantation, intended to facilitate successful left ventricular assist device removal and prevent recurrent dilatation.

Anastomosis, Surgical↗

PubMed1986

Surgical practice kit. Ophthalmic suture simulator.

A practice surgery device used for training novice ophthalmic surgeons employs an inflatable bladder that supports a human bank scleral shell. The sclera is used for placement of sutures. A light source and universal joint to support a syringe are mounted on a 25 X 15-cm base. Glycerin-preserved sclera is available from many eye banks. Up to 100 practice sutures may be placed in each scleral shell. This device allows the beginning surgeon the opportunity to obtain a feel for needle passage through tissue. Technique for the use of loupe or microscope magnification can also be developed. In addition, a deflation of the scleral "globe" occurs when a needle is placed too deeply. This emphasizes the need of superficial suture placement.

Humans↗