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At least 667 records · Page 37Linked to original sources
PubMed1998

Femoral nerve lesion in total hip replacement: an experimental study.

A total of 20 hip joints of 10 non-fixed corpses were examined within 48 h of death to measure the pressure below the inguinal ligament simulating the surgical conditions during total hip arthroplasty. The purpose of this study was to assess the influence of various leg positions and insertion techniques of retractors during the surgical procedure for total hip replacement in order to detect supposed causes for indirect pressure injuries of the femoral nerve. The obtained results verified no increase of pressure in the inguinal canal which could explain an indirect injury of the femoral nerve. If the retractor is inserted correctly at the anterior acetabular rim, the pressure in the lacuna musculorum can even be reduced, and furthermore, the femoral nerve is protected by the iliopsoas muscle. Femoral nerve lesions which have been published so far can only be explained by an incorrect use of instruments or implants (e.g., screws, cement, acetabular cup) or an extreme postoperative leg length discrepancy.

Arthroplasty, Replacement, Hip↗
PubMed1984

Combined topical and systemic antibiotic prophylaxis in experimental wound infection.

The effectiveness of a combined topical and systemic antibiotic regimen was studied in an animal model previously shown to simulate clinical surgical wound infection. At a high level of bacterial contamination, the combination regimen produced a lower infection rate than either a placebo (p less than 0.01), a topical antibiotic administered alone (p less than 0.01), or a systemic antibiotic administered alone. At a lower level of bacterial contamination, no additional reduction in infection rates was produced by the combination regimen when compared with systemic antibiotic administered alone. These experimental results suggest that when wound contamination is great, a combination of topical and systemic antibiotics is the more effective regimen. Where wound contamination is less severe, systemic antibiotic prophylaxis is all that is required; no further benefit is obtained by the additional administration of topical antibiotics. Clinical trials appear justified to confirm or refute this hypothesis.

Administration, Topical↗
PubMed1987

Microbial contamination associated with routine aseptic practice.

We have studied the rate of fortuitous contamination associated with routine aseptic technique under operational conditions. Stainless steel strips, as simulators of surgical instruments, were contained in sterilized surgical packs and assayed by nursing personnel during surgical and other invasive procedures at three different hospitals. The rates of contamination observed for the 36 investigators ranged from 0% to 11.3%, with an overall rate of 2.7%. Assays conducted in a clean room environment, under conditions approaching industrial sterility standards, showed a contamination rate of 0.16%. We concluded that aseptic practices, as routinely performed without any noticeable breaks or transgressions, do not guarantee sterility. The concept of surgical sterility implies low level, but measurable, microbial contamination.

Antisepsis↗
PubMed2006

Biomechanical comparison of a unique locking plate versus a standard plate for internal fixation of proximal humerus fractures in a cadaveric model.

BACKGROUND: Newer internal fixation devices with a locking mechanism between the plate and the screw have recently been released. The efficacy of these plates in the proximal humerus has yet to be fully described. There is a need to compare the biomechanical properties of efficacy of plate fixation with or without locking screws for surgery of two-part proximal humerus fractures. Multiple-plane locking plate and cloverleaf plate designs were tested to determine their ability to maintain fixation on the humeral head. METHODS: Eight matched pairs of cadaveric shoulders with 7-millimeter osteotomy defects at the surgical neck simulating two-part fractures of the proximal humerus were loaded to failure in thirty degrees of glenohumeral abduction. One side was repaired with a proximal humerus locking plate and the other with a cloverleaf plate. The rotator cuff musculature was then loaded via a servo-hydraulic testing machine under displacement control to simulate the deforming forces present in vivo. FINDINGS: The average maximum load to failure was greater in proximal humerus locking plates than in cloverleaf plates (876 versus 712; P=0.04). INTERPRETATION: In the cadaveric, two-part proximal humerus fracture model that was created, the locking plate displayed significantly greater holding power of the humeral head. Clinical relevance is unproven but may be manifested in vivo as improved early range of motion exercises and functional outcome.

Aged↗
PubMed2004

Using high-fidelity patient simulation and an advanced distance education network to teach pharmacology to second-year medical students.

The feasibility and acceptance of an Advanced Distance Education Network (ADEN) in bringing the simulated operating room (OR) to second-year medical students learning the pharmacology of anesthetic drugs is reviewed. A MedSim-Eagle (Binghamton, NY) full-scale mannequin simulator was used. Using an ADEN, students were linked in real time to a simulated OR where the anesthesiologist instructor was using a MedSim-Eagle patient simulator to present for discussion the physiologic effects of volatile anesthetics on cardiac output (CO), heart rate (HR), mean arterial pressure (MAP), and systemic vascular resistance (SVR). The use of simulation to present basic science principles of isoflurane and halothane's effect on CO, HR, MAP, and SVR in a clinical setting via an ADEN is feasible. Student acceptance of this method of education is high, as measured by a post-exercise survey. Ninety-five percent of students felt this exercise was a valuable use of their time; 93% felt the ADEN-delivered clinical simulation presentation contributed to their understanding of the pharmacology of anesthesia. Eighty-three percent of students preferred this integrated clinically oriented review to a didactic review of the material, and 92% of students who had experienced previous small group hands-on session simulation felt the ADEN-delivered session was the same or better.

Anesthesiology↗
PubMed2000

Constitutive modelling of abdominal organs.

Abdominal organs are very susceptible to trauma. In order to protect them properly against car crash and other impact consequences, we need to be able to simulate the abdominal organ deformation. Such simulation should account for proper stress-strain relation as well as stress dependence on strain rate. As the step in this direction, this paper presents three-dimensional, non-linear, viscoelastic constitutive models for liver and kidney tissue. The models have been constructed basing on in vivo experiments conducted in Highway Safety Research Institute and the Medical Centre of The University of Michigan (Melvin et al., 1973). The proposed models are valid for compressive nominal strains up to 35% and fast (impact) strain rates between 0.2 and 22.5 s(-1). Similar models can find applications in computer and robot assisted surgery, e.g. the realistic simulation of surgical procedures (including virtual reality) and non-rigid registration.

Abdominal Injuries↗
PubMed1997

The pregnant ewe: an animal model for fetoscopic surgery.

OBJECTIVE: To develop an animal model for fetal endoscopic surgery which could be feasible and reproducible. The aim of this work was to perform a fetoscopy without the need of a laparotomy. METHODS: Pregnant ewes underwent under general anesthesia laparoscopy with the creation of a maternal pneumoperitoneum. After localizing the placenta by transillumination, we carried out fetoscopy through a 5 mm trocar using a perfusion of Ringer's solution. RESULTS: Five video-assisted procedures have been performed. None of the cases has shown any bleeding from myometrial wounds and no suture was necessary. There was no leakage of amniotic fluid. Intrauterine space was large enough to manipulate instruments without producing any fetal damage. Sharp visualization and anatomical description of the fetus were precise without the use CO2. There were no miscarriages and postnatal examinations of the lambs were normal. CONCLUSION: Fetoscopic surgery can be performed in the pregnant sheep without any complications but preterm labor which is the main problem in human fetal surgery, is infrequent in the sheep. Our model is reproducible and simulates the surgical endoscopic procedures which will occur in a close future in the human species.

Animals↗
PubMed1998

Increasing spiral CT benefits with postprocessing applications.

This paper reviews the current and future role of various postprocessing tools for epidemiologically important diseases. It introduces a generic business system for diagnosis and treatment using Spiral CT. Postprocessing of Spiral CT data should become a routine part of radiological practice. As viewing moves from film to monitor displays, interactive postprocessing tools support evaluation of CT studies and will in some cases also improve diagnostic accuracy. Track-ball controlled browsing through the volume data may be performed on axial images or on multiplanar reformats (MPR). These tools can be expected to become an integral part of most CT evaluations in the near future. Already now, MPR are important adjuncts for most orthopaedic applications. Presently, three-dimensional (3D) displays are used mainly in orthopaedic and trauma patients. In CT angiography, 3D surface displays and maximum intensity projections are routine display modalities. New volume rendering techniques (VRT) with interactive parameter changes will make 3D imaging of soft tissues feasible as well. The key input factor for many postprocessing applications will be Spiral CT data sets with high z-axis resolution (subsecond scanning, thin collimation, overlapping image reconstruction) and optimised application of contrast media. The most important benefit of postprocessing is the communication with the referring physician since 3D representations are becoming increasingly important for treatment planning and control. Postprocessing services will become a key ingredient of a successful radiological practice. If radiology does not provide it, the other physicians will do it themselves. For treatment simulation, virtual surgical instruments and tissue motion models are still in their infancy and will keep software architects and physicians busy for the next decade of Spiral-CT.

Humans↗
PubMed1999

A new approach to computer guidance in orthopedic surgery using real time volume rendering.

The purpose of this paper was to evaluate the ability of a new real time volume rendering system using raw unprocessed CT data on a four processor Pentium PC. A CT data set of the pelvic area was used to demonstrate the systems ability to integrate and visualize both data from a CT scan and a tracking system. The computer system consisted of a four processor Pentium PC and the software tool VGInsight (Volume Graphics GmbH). For study purposes in a laboratory setting a magnetic tracking system (Polemus Inc.) was used to simulate tracked surgical tools. With this new software tool and the tracking system the exact relative location of a tracked instrument within all structures of the pelvic area, soft tissue as well as bone, could be displayed in 3D and real time without preprocessing of the data set. Until recently real time volume rendering required expensive workstations. With a new software tool on a four processor Pentium PC the authors were able to introduce a 3D real time processed data supply to the surgeon.

Fractures, Bone↗
PubMed2003

Methotrexate in the management of granulomatous mastitis.

Granulomatous mastitis is a rare benign inflammatory breast disease that often clinically simulates carcinoma. Surgical resection of the entire lesion has been the main method of treatment but recurrence, infection, sinus formation and delayed wound healing can occur relatively commonly. Corticosteroids are also effective in recurrent or resistant cases but are associated with side-effects and relapse of disease after steroid withdrawal. A low weekly oral dose of methotrexate was used in five resistant cases after surgery plus corticosteroid. All cases achieved remission, withdrawal of corticosteroid without relapse and no methotrexate side-effect.

Adult↗
PubMed2006

The effect of exercise on peripheral muscle in emphysema: a preliminary investigation.

Emphysema has been associated with loss of aerobic muscle fibers and decreased blood supply. However, when these changes begin and whether exercise can prevent these changes is unknown. The purpose of this study was to examine peripheral muscle at different time points during the development of emphysema and to determine the additional effects of muscle activity. In a series of 3 experiments, emphysema was induced in hamsters. Exercise was simulated through surgical overload (OV) of the plantaris muscle of one leg. Animals were sacrificed at 1, 3, and 5 months following emphysema induction. Fiber type composition and capillary-to-fiber ratio (CFR) were determined. There were no significant changes in fiber type composition in the 1-month group. A significant increase in type IIA fiber composition (mean 72.0 vs. 54.5%) and decrease in type IIB fiber (mean 13.3 vs. 28.1%) was seen in the non-overloaded muscles following 3 months. In the 5-month group, there was a significant decrease in percentage of type I fibers (mean 14.7 vs. 28.0%). There were no significant differences in fiber type composition in the OV limb, regardless of duration. The CFR was significantly lower in the OV limb after 5-months of emphysema (mean 0.92 vs. 1.55 cap/fiber). Muscle overload prevented emphysema-associated changes in fiber type composition, but not in CFR. Peripheral muscle is affected early in the course of emphysema and chronic overload may play an important role in preserving normal muscle composition.

Animals↗
PubMed2005

Patellofemoral joint biomechanics and tissue engineering.

Recent advances in the study of patellofemoral joint biomechanics have provided promising diagnosis and treatment modalities for patellofemoral joint disorders, such as quantitative assessment of cartilage lesions from noninvasive imaging, computer simulations of surgical procedures for optimizing surgical parameters and potentially predicting outcomes, and cartilage tissue engineering for the treatment of advanced degenerative joint disease. These technologies are still in development and their clinical potentials remain an ongoing topic of investigation. We review some of our progress in addressing these issues, and the important role of cartilage mechanics and lubrication in understanding the challenges regarding patellofemoral surgery and cartilage tissue engineering.

Biomechanical Phenomena↗
PubMed1997

Virtual reality in medicine-computer graphics and interaction techniques.

This paper describes several new visualization and interaction techniques that enable the use of virtual environments for routine medical purposes. A new volume-rendering method supports shaded and transparent visualization of medical image sequences in real-time with an interactive threshold definition. Based on these rendering algorithms two complementary segmentation approaches offer an intuitive assistance for a wide range of requirements in diagnosis and therapy planning. In addition, a hierarchical data representation for geometric surface descriptions guarantees an optimal use of available hardware resources and prevents inaccurate visualization. The combination of the presented techniques empowers the improved human-machine interface of virtual reality to support every interactive task in medical three-dimensional (3-D) image processing, from visualization of unsegmented data volumes up to the simulation of surgical procedures.

Algorithms↗
PubMed1975

A comparison between direct and indirect measurements of blood flow in the follicular ovary of the rabbit.

A comparison was carried out between direct and indirect measurements of blood flow in follicular ovaries of anaesthetized laparotomized rabbits: Direct measurements by timed quantitative sampling of ovarian venous blood yielded blood flow values 3 times higher than those found with the use of 15 mugm radioactive microspheres. However, when simulating the surgical trauma associated with direct measurements, the microsphere technique gave the same high ovarian flow values, indicating that this type of trauma caused ovarian hyperemia. It is concluded that direct measurements of blood flow, as performed in the present study, are unsuitable for investigations of circulatory events in the ovary. Mechanically induced ovarian vasodilatation is probably a factor which helps to explain the diverging data on blood flow obtained with direct and indirect methods. The radioactive microsphere technique appears to provide a means for reasonably reliable ovarian blood flow measurements in laboratory animals.

Animals↗
PubMed2002

Volume reconstruction for health care: a survey of computational methods.

In many scientific and technical applications, a three-dimensional (3D) object must be reconstructed, either to assist in understanding the object's structure or to ease its automatic handling and analysis. Volume reconstruction has been used in health care to diagnose, simulate, facilitate surgical planning, develop image-guided surgery, facilitate telemedicine, and to assist in many other applications. This paper presents a survey of computational methods used to achieve volume reconstruction. First, we review 3D imaging techniques. Second, since we consider image segmentation the most important and difficult phase of 3D reconstruction, we focus on this topic. Subsequently, we concentrate on some of the most successful techniques of segmentation used for 3D reconstruction, such as active contours. We also review computer graphics and visualization methods used with volume reconstruction. Finally, we indicate future lines for research in volume reconstruction and 3D imaging for health care.

Brain↗
PubMedDate not supplied

Force displacement characteristics of the posterior cruciate ligament.

The percent force changes in the posterior cruciate ligament were calculated using a previously validated computerized knee model after the femoral insertion sites were varied 2.5 and 5.0 mm in an anterior, posterior distal, anterior distal, and posterior distal direction. The tibial insertion sites were also varied 2.5 and 5.0 mm in the medial, lateral, proximal, and distal directions. Percent force changes were measured over a range of 0 degree to 90 degrees. These insertion sites simulated potential surgical placement errors. Results of this study demonstrated that the greatest percent force changes in the posterior cruciate ligament were at full extension. The greatest absolute percent force change between 0 degree and 90 degrees of flexion was with a femoral insertion of the posterior cruciate ligament placed 5 mm anterior to its normal attachment site, which resulted in a 39% change in the posterior cruciate ligament force. Distal femoral site attachment had the least effect (10% at 5.0 mm). Alterations at the tibial attachment site were less sensitive than on the femur; the greatest absolute percent force changes occurred with medial and lateral attachment sites (14% and 15%, respectively, at 5.0 mm). A minimal amount of percent force changes were seen between 45 degrees and 75 degrees of knee flexion in all positions tested for both tibial and femoral attachment sites. This model suggests that, like the anterior cruciate ligament, the force in the posterior cruciate ligament is also sensitive to attachment site position. As in anterior cruciate ligament studies, the femoral attachment site was found to be more sensitive.(ABSTRACT TRUNCATED AT 250 WORDS)

Biomechanical Phenomena↗