Use of a virtual reality, real-time, simulation model for the training of urologists in transurethral resection of the prostate

OBJECTIVE: There is a growing need to develop surgical skills outside the operating theatre. In this study we describe the development of a virtual reality training system for practising transurethral resection of the prostate (TURP). MATERIAL AND METHODS: A face validity study was performed using a questionnaire sent to 28 experienced urologists to find out the ideal characteristics of a simulated TURP. Based on the comments a simulator was constructed and a content validity study was then performed in which nine experienced urologists tested the simulator and answered a second questionnaire. After corrections to the simulator, a basic construct validity test was performed. RESULTS: We have developed a computer-based simulator based on the requirements listed by 17 urologists. It consists of a modified resectoscope connected to a haptic device and supported by a frame. The software provides a virtual view of the prostatic lumen and resectoscope tip, a haptic rendering that generates force feedback and a simulation module that computes the information from the haptic device, resectoscope fluid tap and handle and the foot pedals. The software also simulates bleeding, absorption of irrigation fluid and pressure gradients. Variables are measured and presented in a result file after each "operation". Nine experienced urologists performed a content validity study and changes were made accordingly. A basic construct validity test performed by seven inexperienced students showed a significant improvement in performance after they each performed six simulated procedures. CONCLUSION: We have developed a simulator that may be used to practise TURP and which meets most of the demands raised in a face validity study. A basic construct validity test showed improved performance after repeated practice in the simulated environment.     

Large femoral bone loss after hip revision using the uncemented proximally porous-coated Bi-Metric prosthesis: 22 hips followed for a mean of 6 years

Background and purpose Periprosthetic bone loss after uncemented femoral hip revision is a matter of concern. We have used a proximally porous- and hydroxyapatite-coated prosthesis (Bi-Metric) in revision since 1989 and now we report the bone changes. This prosthesis is intended to distribute the forces more evenly and to avoid proximal femoral unloading.Methods 22 patients were unilaterally reoperated because of aseptic loosening. Only patients with a healthy contralateral hip were included. Mean age at revision was 69 (55–80) years. Bone defects were graded by Gustilo-Pasternak and Endo-Klinik classifications. Clinical assessment was performed with Harris hip score. We used radiographs and dual-energy X-ray absorptiometry to evaluate migration, femoral remodeling, and bone mineral density after 72 (30–158) months.Results The mean Harris hip score was 74 (30–100) points at follow-up. Mild thigh discomfort was present in 1 patient and moderate thigh pain in 3 patients. There was no loosening or subsidence. Osteolysis seen at revision had diminished in 19 of the 22 hips at follow-up. We noted a large reduction in bone mineral density. It was most pronounced in Gruen regions 1, 2, 6, and 7.Interpretation Revision with this stem is a reliable procedure; however, we noted a large degree of proximal bone loss that could lead to later mechanical complications or fractures.     

Saturation‐recovery metabolic‐exchange rate imaging with hyperpolarized [1‐13C] pyruvate using spectral‐spatial excitation

Within the last decade hyperpolarized [1‐¹³C] pyruvate chemical‐shift imaging has demonstrated impressive potential for metabolic MR imaging for a wide range of applications in oncology, cardiology, and neurology. In this work, a highly efficient pulse sequence is described for time‐resolved, multislice chemical shift imaging of the injected substrate and obtained downstream metabolites. Using spectral‐spatial excitation in combination with single‐shot spiral data acquisition, the overall encoding is evenly distributed between excitation and signal reception, allowing the encoding of one full two‐dimensional metabolite image per excitation. The signal‐to‐noise ratio can be flexibly adjusted and optimized using lower flip angles for the pyruvate substrate and larger ones for the downstream metabolites. Selectively adjusting the excitation of the down‐stream metabolites to 90° leads to a so‐called “saturation‐recovery” scheme with the detected signal content being determined by forward conversion of the available pyruvate. In case of repetitive excitations, the polarization is preserved using smaller flip angles for pyruvate. Metabolic exchange rates are determined spatially resolved from the metabolite images using a simplified two‐site exchange model. This novel contrast is an important step toward more quantitative metabolic imaging. Goal of this work was to derive, analyze, and implement this “saturation‐recovery metabolic exchange rate imaging” and demonstrate its capabilities in four rats bearing subcutaneous tumors. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc.     

The hospital cost of vertebral fractures in the EU: estimates using national datasets

The purpose of this study was to estimate the hospital cost of vertebral fractures in the EU using national datasets to explore some of the methodologic limitations associated with such an approach. Hospital costs for vertebral fractures across the EU were compared with the hospital costs associated with hip fractures. Additionally, these costs were placed into the health care context by making comparisons with national health care expenditure. All EU Ministries of Health were contacted to identify national datasets to estimate the average length of stay, cost per diem and the number of patients discharged with vertebral fractures. Where national information was not available expert opinion and data from the relevant literature were used instead. Countries show a marked difference in the length of stay between men and women, with differences ranging from 0.32 days in Austria to 20.2 days in Spain. The average hospitalization rate was found to be 8% across the EU, with higher rates found for men than for women. Interestingly a positive correlation between health expenditure per capita and hospitalization rates was found. The total cost of vertebral fractures in the EU was estimated at euro 377 million per year. Across the EU the hospital cost of a vertebral fracture was on average 63% that of a hip fracture. National datasets allow us to estimate the cost of vertebral fractures in the EU but show limitations. In the absence of large scale prospective studies, national datasets need to be further refined to ensure more accurate estimations of the cost of vertebral fractures in the EU.     

Extracellular Gd-CA: differences in prevalence of NSF

Until recently it was believed that extracellular gadolinium-based contrast agents were safe for both the kidneys and all other organs within the dose range up to 0.3 mmol/kg body weight. However, in 2006, it was demonstrated that some gadolinium-based contrast agents may trig the development of nephrogenic systemic fibrosis, a generalized fibrotic disorder, in renal failure patients. As no prospective studies can be performed we must rely on retrospective data. From those data it is obvious that the prevalence of NSF is significantly higher after the unstable agent gadodiamide than after any other gadolinium-based agent (3–7% versus 0–1% per injection) in patients with reduced renal function. Prevalence after exposure to two gadodiamide injections is as high as 36% in patients with chronic kidney disease (CKD) stage 5. No report of NSF after the most stable agents has been reported in the peer-reviewed literature documenting that there is a difference between the various agents regarding triggering NSF.     

Calcineurin inhibitor sparing in renal transplantation

Although calcineurin inhibitors (CNIs) are effective at preventing acute rejection, their long-term use is associated with nephrotoxicity that may compromise long-term renal allograft survival. Consequently, there is considerable interest in identifying immunosuppressive regimens that permit reduced exposure to CNIs while maintaining adequate immunosuppression. Introducing such strategies early after transplantation may mean that the development of CNI-associated nephrotoxicity could be minimized or prevented. Several CNI-sparing regimens have shown at least comparable efficacy with standard-dose CNI regimens. In particular, a regimen of mycophenolate mofetil (MMF), corticosteroids, interleukin-2 receptor antagonist induction, and low-dose tacrolimus from the time of transplantation provided superior renal function and a lower acute rejection rate than the same regimen but with low-dose cyclosporine or low-dose sirolimus, or standard-dose cyclosporine, MMF, and corticosteroids. The use of low-dose cyclosporine does not seem to eliminate nephrotoxicity in de novo renal transplant recipients. The early withdrawal of CNIs from MMF-based regimens generally improves renal function but has been associated with an increased risk of acute rejection, in particular when the levels of mycophenolic acid were not adjusted to maintain the same total level of immunosuppression. Research aiming to achieve the "best" balance of efficacy and toxicity of available immunosuppressive regimens continues.     

Incidence and risk factors for low trauma fractures in men with prostate cancer

BACKGROUND: Men with prostate cancer on androgen deprivation therapy (ADT) are at increased risk of bone loss. The present study sought to determine the incidence of low trauma fracture in men with prostate cancer (PC), and to characterize the association between potential risk factors and fracture risk in these men. METHODS: In the prospective, population-based Dubbo Osteoporosis Epidemiology Study, 43 men aged 60+ years reported a history of prostate cancer; among whom, 22 men received ADT, and 21 men did not. Low-trauma fractures were ascertained between 1989 and 2004. Bone mineral density at the femoral neck (FNBMD), postural instability and lifestyle factors were obtained at baseline. RESULTS: Men with prostate cancer had significantly higher lumbar spine BMD than those without cancer (p=0.013). During the follow-up period, 15 men with prostate cancer had sustained a fracture, yielding the age-adjusted incidence of fracture among this group was 31.6 per 1000 person-years, which was greater than those without cancer (22.1 per 1000 person-years). The age-adjusted incidence of fracture was more pronounced among those with prostate cancer on ADT (40.2 per 1000 person-years). After adjusting for age, the increase in fracture risk among prostate cancer patients was associated with lower femoral neck BMD (hazard ratio [HR] per SD=1.8, 95% CI: 1.0-3.4) and increased rate of bone loss (HR 2.3, 1.2-4.6). CONCLUSIONS: Men with prostate cancer, particularly those treated with ADT, had an increased fracture risk. Although the average BMD in men with prostate cancer was higher than men without cancer, a low BMD prior to treatment or increased rate of bone loss after initiating ADT treatment was each a significant predictor of fracture in these.     

Amiodarone protects diabetics and non-diabetics undergoing coronary artery bypass grafting equally

OBJECTIVE: To evaluate amiodarone prophylaxis in diabetics and non-diabetics. Further to clarify whether the risk of developing atrial fibrillation is higher for diabetics than non-diabetic patients, and to evaluate whether the diabetic status has any influence on the length of in-hospital stay. DESIGN: Subgroup analysis within a randomized, controlled, double-blinded trial. RESULTS: At 30 days of follow-up atrial fibrillation was equally frequent among diabetics (22%) and non-diabetics (17%) (p =0.41). The length of in-hospital stay for diabetics was prolonged with 25% (9%; 45%). The prophylactic amiodarone was found equally efficient in diabetics and non-diabetics, as the relative risk ratios were 1.2 (0.4-5.4) and 2.0 (0.3-12.5), respectively. CONCLUSIONS: Diabetics and non-diabetics had the same effect of the amiodarone prophylaxis regime. Atrial fibrillation developed equally among diabetics and non-diabetics, but the length of stay was prolonged for diabetics.     

Characteristics of children with hip displacement in cerebral palsy

Background  

Hip dislocation in children with cerebral palsy (CP) is a common and severe problem. The dislocation can be avoided, by screening and preventive treatment of children with hips at risk. The aim of this study was to analyse the characteristics of children with CP who develop hip displacement, in order to optimise a hip surveillance programme.