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Surgical Tool (surgical + tool)

Distribution by Scientific Domains

Medical Sciences	75%

Selected Abstracts

Improving realism of a surgery simulator: linear anisotropic elasticity, complex interactions and force extrapolation

COMPUTER ANIMATION AND VIRTUAL WORLDS (PREV: JNL OF VISUALISATION & COMPUTER ANIMATION), Issue 3 2002
Guillaume Picinbono
Abstract In this article, we describe the latest developments of the minimally invasive hepatic surgery simulator prototype developed at INRIA. The goal of this simulator is to provide a realistic training test bed to perform laparoscopic procedures. Therefore, its main functionality is to simulate the action of virtual laparoscopic surgical instruments for deforming and cutting tridimensional anatomical models. Throughout this paper, we present the general features of this simulator including the implementation of several biomechanical models and the integration of two force-feedback devices in the simulation platform. More precisely, we describe three new important developments that improve the overall realism of our simulator. First, we have developed biomechanical models, based on linear elasticity and finite element theory, that include the notion of anisotropic deformation. Indeed, we have generalized the linear elastic behaviour of anatomical models to ,transversally isotropic' materials, i.e. materials having a different behaviour in a given direction. We have also added to the volumetric model an external elastic membrane representing the ,liver capsule', a rather stiff skin surrounding the liver, which creates a kind of ,surface anisotropy'. Second, we have developed new contact models between surgical instruments and soft tissue models. For instance, after detecting a contact with an instrument, we define specific boundary constraints on deformable models to represent various forms of interactions with a surgical tool, such as sliding, gripping, cutting or burning. In addition, we compute the reaction forces that should be felt by the user manipulating the force-feedback devices. The last improvement is related to the problem of haptic rendering. Currently, we are able to achieve a simulation frequency of 25,Hz (visual real time) with anatomical models of complex geometry and behaviour. But to achieve a good haptic feedback requires a frequency update of applied forces typically above 300,Hz (haptic real time). Thus, we propose a force extrapolation algorithm in order to reach haptic real time. Copyright © 2002 John Wiley & Sons, Ltd. [source]

Terahertz pulsed imaging of basal cell carcinoma ex vivo and in vivo

BRITISH JOURNAL OF DERMATOLOGY, Issue 2 2004
V.P. Wallace
Summary Background, Terahertz radiation lies between the infrared and microwave regions of the electromagnetic spectrum and can be used to excite large amplitude vibrational modes of molecules and probe the weak interactions between them. Terahertz pulsed imaging (TPI) is a noninvasive imaging technique that utilises this radiaton. Objectives, To determine whether TPI could differentiate between basal cell carcinoma (BCC) and normal tissue and to test whether it can help facilitate delineation of tumour margins prior to surgery. Methods, A portable TPI system was used in the clinic to image 18 BCCs ex vivo and five in vivo. Results, The diseased tissue showed a change in terahertz properties compared with normal tissue, manifested through a broadening of the reflected terahertz pulse. Regions of disease identified in the terahertz image correlated well with histology. Conclusions, This study has confirmed the potential of TPI to identify the extent of BCC in vivo and to delineate tumour margins. Further clinical study of TPI as a surgical tool is now required. [source]

History and Current Practice of Tonsillectomy

THE LARYNGOSCOPE, Issue S100 2002
Ramzi T. Younis MD
Abstract Objective To review important developments in the history of adenotonsillectomy and describe current methods and results for the operation. Study Design Review. Methods Tonsillectomy practices since antiquity were reviewed, with emphasis on introductions of new surgical tools and procedures, anesthesia methods, and patient care practices. Past and current indications for and complications associated with tonsillectomy were also reviewed. Results Devices used for adenotonsillectomy have included snares, forceps, guillotines, various kinds of scalpels, lasers, ultrasonic scalpels, powered microdebriders, and bipolar scissors. General anesthesia, the Crowe-Davis mouth gag, and methods for controlling bleeding have contributed greatly to success with the operation. Past and current indications for adenotonsillectomy are similar, although the relative importance of some indications has changed. The complication rate has declined, but the problems that do occur remain the same. Currently, cost-effectiveness is a principal concern. Conclusion The instruments and procedures used for adenotonsillectomy have evolved to render it a precise operation. Today, the procedure is a safe, effective method for treating breathing obstruction, throat infections, and recurrent childhood ear disease. [source]

Homologous Collagen Substances for Vocal Fold Augmentation

THE LARYNGOSCOPE, Issue 5 2001
Mark S. Courey MD
Abstract Objectives/Hypothesis Dysphonia resulting from failure of glottic closure during voicing is a difficult clinical problem. Recently developed homologous collagen compounds may be beneficial in treating this problem. The objectives of this thesis are to: 1) evaluate the potential site(s) of collagen graft placement in the human vocal fold, quantify the amount of graft material that can be injected into these sites, and determine how these sites are accessed by the currently available surgical tools for injection; 2) determine the effects of the superficial vocal fold implant on laryngeal vibratory patterns and characterize how the implant affects the forces required to bring vocal folds into an adducted position for vibration; and 3) evaluate the host response to two different forms of cadaveric collagen. Study Design Prospective laboratory. Methods Three separate experiments were undertaken: 1) Eight cadaver larynges were injected with collagen compounds through a 27-gauge needle. The amount of substance required to medialize the vocal fold and potential positions for graft placement were evaluated. 2) Six cadaver larynges were mounted on a stabilizing stand while airflow, vocal fold length, adduction forces, and abduction forces on the vocal folds were manipulated. Vibratory patterns before and after the injection of the vocal folds with solubilized collagen were assessed. 3) A nude mouse model was used to study the host response to two different exogenous collagen compounds. Results Solubilized collagen compounds could be injected reliably into the superficial layer of the lamina propria (SLLP), medial portion of the thyroarytenoid muscle, or lateral portion of the thyroarytenoid muscle. When injected superficially, significantly less material was required to displace the medial edge of the vocal fold to midline (P = .0001). When graft material was placed into the medial portion of the thyroarytenoid (TA) muscle, the forces required to bring the vocal fold into a position suitable for vibration were significantly reduced (P = .0106) and the vibratory patterns of the vocal folds were not impaired. Both AlloDerm® and Dermalogen® solubilized preparations of human dermal tissue were well tolerated in the nude-mouse model. Minimal inflammatory reaction occurred. Small amounts of graft material were identified histologically at the end of the 6-month study period. The graft material appeared organized and had been infiltrated with fibroblasts of host origin. Conclusions Homologous collagen compounds can be reliably injected into the cadaveric human larynx. When the substances are injected into the medial portion of the TA muscle, immediately deep to the vocal ligament, they decrease the force of contraction needed to bring the vocal folds into a position adequate for phonation and have minimal affect on the vibratory patterns. These forms of homologous collagen are well tolerated. A small amount persists over a 6-month interval. These materials warrant further clinical trials in human subjects. [source]