A randomised controlled trial of total hip arthroplasty versus resurfacing arthroplasty in the treatment of young patients with arthritis of the hip joint

Background: Hip replacement (arthroplasty) surgery is a highly successful treatment for patients with severe symptomatic arthritis of the hip joint. For older patients, several designs of Total Hip Arthroplasty have shown excellent results in terms of both function and value for money. However, in younger more active patients, there is approximately a 50% failure rate at 25 years for traditional implants. Hip resurfacing is a relatively new arthroplasty technique. In a recent review of the literature on resurfacing arthroplasty it was concluded that the short-term functional results appear promising but some potential early disadvantages were identified, including the risk of femoral neck fracture and collapse of the head of the femur. The aim of the current study is to assess whether there is a difference in functional hip scores at one year post-operation between Total Hip Arthroplasty and Resurfacing Arthroplasty. Secondary aims include assessment of complication rates for both procedures as well cost effectiveness. Methods/design: All patients medically fit for surgery and deemed suitable for a resurfacing arthroplasty are eligible to take part in this study. A randomisation sequence will be produced and administered independently. After consenting, all patients will be clinically reviewed and hip function, quality of life and physical activity level will be assessed through questionnaires. The allocated surgery will then be performed with the preferred technique of the surgeon. Six weeks post-operation hip function will be assessed and complications recorded. Three, six and 12 months post-operation hip function, quality of life and physical activity level will be assessed. Additional information about patients' out-of-pocket expenses will also be collected

Collisional transport across the magnetic field in drift-fluid models

Drift ordered fluid models are widely applied in studies of low-frequency turbulence in the edge and scrape-off layer regions of magnetically confined plasmas. Here, we show how collisional transport across the magnetic field is self-consistently incorporated into drift-fluid models without altering the drift-fluid energy integral. We demonstrate that the inclusion of collisional transport in drift-fluid models gives rise to diffusion of particle density, momentum and pressures in drift-fluid turbulence models and thereby obviate the customary use of artificial diffusion in turbulence simulations. We further derive a computationally efficient, two-dimensional model which can be time integrated for several turbulence de-correlation times using only limited computational resources. The model describes interchange turbulence in a two-dimensional plane perpendicular to the magnetic field located at the outboard midplane of a tokamak. The model domain has two regions modeling open and closed field lines. The model employs a computational expedient model for collisional transport. Numerical simulations show good agreement between the full and the simplified model for collisional transport

The effect of surgical approach on the histology of the femoral head following resurfacing of the hip : analysis of retrieval specimens

Objectives: We aimed to determine the effect of surgical approach on the histology of the femoral head following resurfacing of the hip. Methods: We performed a histological assessment of the bone under the femoral component taken from retrieval specimens of patients having revision surgery following resurfacing of the hip. We compared the number of empty lacunae in specimens from patients who had originally had a posterior surgical approach with the number in patients having alternative surgical approaches. Results: We found a statistically significant increase in the percentage of empty lacunae in retrieval specimens from patients who had the posterior approach compared with other surgical approaches (p < 0.001). Conclusions: This indicates that the vascular compromise that occurs during the posterior surgical approach does have long-term effects on the bone of the femoral head, even if it does not cause overt avascular necrosis

Danmark er nu Europamester i økologisk regnbueørred

Danmark er nu Europas største producent af økologiske regnbueørreder, med en samlet produktion i 2014 på 1.080 tons. De økologiske producenter af regnbueørred har vist sig at have en bedre økonomisk indtjening per produceret enhed, end tilsvarende konventionelle producenter. Der blev genereret en 8% højere indtægt per enhed og en solvens på 28 % i 2012, hvilket er betydelig bedre i forhold til tilsvarende konventionelle producenter (solvens er et udtryk for kreditværdighed). De danske producenter og tilhørende forarbejdningsindustri er nu i front på markedet for økologiske ørreder. I dag er det muligt at levere råvaren kontinuerligt igennem året. Produktkataloget er udvidet betydeligt, da også store regnbueørreder fra et saltvandsdambrug er blevet godkendt som økologisk produceret. Der er nu flere forskellige forædlingsvirksomheder. Disse sikre flere afsætningsmuligheder for primærproducenterne. Der er flere primærproducenter, der har tilladelse til ”stalddørssalg”. Ellers kan økologiske regnbueørred primært købes i supermarkedskæderne og et begrænset antal fiskehandlere. Et område som man forventer sig meget af er foodservice sektoren, efter indførelsen af det økologiske spisemærke. En salgsparameter for økologiske regnbueørred, kan være mærkning af salgspakkerne. Empiriske resultater viser at forbrugerne er villige til at betale mellem 24 til 38% mere for et sådant produkt. Undersøgelsen af villighed til at betale mere for et produkt er forbundet med relativ høj usikkerhed, så den reelle betalingsvillighed kunne nærme sig forskellen for fisk med bæredygtighedsmærke i forhold til fisk uden mærke. Der er gennemført et litteraturstudie af relevante undersøgelser af forbrugernes forventninger til økologisk fisk. Resultatet af denne undersøgelse er ikke direkte relevant, da nogle af studierne er af ældre dato (mere end 15 år gamle) eller det er studier fortaget med forbrugere, der intet forhåndskendskab havde til økologisk fisk. De seneste studier viser en mere positiv holdning fra forbrugernes side. Fremtidige trends og tendenser indikerer, at økologisk regnbueørred produkter har en relativ god chance for at erobre en større markedsandel fra de konventionelle produkte

Self-trapping of impurities in Bose-Einstein condensates: Strong attractive and repulsive coupling

We study the interaction-induced localization -- the so-called self-trapping -- of a neutral impurity atom immersed in a homogeneous Bose-Einstein condensate (BEC). Based on a Hartree description of the BEC we show that -- unlike repulsive impurities -- attractive impurities have a singular ground state in 3d and shrink to a point-like state in 2d as the coupling approaches a critical value. Moreover, we find that the density of the BEC increases markedly in the vicinity of attractive impurities in 1d and 2d, which strongly enhances inelastic collisions between atoms in the BEC. These collisions result in a loss of BEC atoms and possibly of the localized impurity itself.Comment: 7 pages, 5 figure

Anomalous diffusion, clustering, and pinch of impurities in plasma edge turbulence

The turbulent transport of impurity particles in plasma edge turbulence is investigated. The impurities are modeled as a passive fluid advected by the electric and polarization drifts, while the ambient plasma turbulence is modeled using the two-dimensional Hasegawa--Wakatani paradigm for resistive drift-wave turbulence. The features of the turbulent transport of impurities are investigated by numerical simulations using a novel code that applies semi-Lagrangian pseudospectral schemes. The diffusive character of the turbulent transport of ideal impurities is demonstrated by relative-diffusion analysis of the evolution of impurity puffs. Additional effects appear for inertial impurities as a consequence of compressibility. First, the density of inertial impurities is found to correlate with the vorticity of the electric drift velocity, that is, impurities cluster in vortices of a precise orientation determined by the charge of the impurity particles. Second, a radial pinch scaling linearly with the mass--charge ratio of the impurities is discovered. Theoretical explanation for these observations is obtained by analysis of the model equations.Comment: This article has been submitted to Physics of Plasmas. After it is published, it will be found at http://pop.aip.org/pop

Cost-effectiveness of total hip arthroplasty versus resurfacing arthroplasty : economic evaluation alongside a clinical trial

Objective: To report on the relative cost-effectiveness of total hip arthroplasty and resurfacing arthroplasty (replacement of articular surface of femoral head only) in patients with severe arthritis suitable for hip joint resurfacing arthroplasty. Design: Cost-effectiveness analysis on an intention-to-treat basis of a single-centre, single-blind randomised controlled trial of 126 adult patients within 12 months of treatment. Missing data were imputed using multiple imputations with differences in baseline quality of life and gender adjusted using regression techniques. Setting: A large teaching hospital trust in the UK. Participants: A total of 126 adult patients with severe arthritis of the hip joint suitable for a resurfacing arthroplasty of the hip. Results: Data were received for 126 patients, 4 of whom did not provide any resource use data. For the remainder, data were imputed for costs or quality of life in at least one time point (baseline, 3, 6 months and 1 year) for 18 patients. Patients in the resurfacing arm had higher quality of life at 12 months (0.795 vs 0.727) and received 0.032 more QALYs within the first 12 months postoperation. At an additional cost of £564, resurfacing arthroplasty offers benefits at £17 451 per QALY within the first 12 months of treatment. When covariates are considered, the health economic case is stronger in men than in women. Conclusions: Resurfacing arthroplasty appears to offer very short-term efficiency benefits over total hip arthroplasty within a selected patient group. The short-term follow-up in this trial should be noted, particularly in light of the concerns raised regarding adverse reactions to metal debris from metal-on-metal bearing surfaces in the longer term. Longer-term follow-up of resurfacing arthroplasty patients and decision analytic modelling is also advised. Trial registration Current controlled Trials: ISRCTN33354155. UKCRN 4093