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There is an increasing demand for tools to assist in the management of environmental flows in rivers. Changes in river discharge act on biota through a hydraulic template which is mediated by channel morphology. Hence environmental flow assessments also need to consider channel morphology, especially if morphology has been altered by human activities. Computer models describing the preferences of fish for hydraulic microhabitats have been applied to environmental flow problems since the mid 1970s. Salmonids have been a particular focus for these methods. Other reviews have provided comprehensive coverage of the basic features and principles of such models. These are briefly discussed before focusing on developments that have occurred in the last 15 years and whose application has so far been infrequent. These include improvements to the representation of hydraulics at reach-scale and of longer river sections, and improved representation of interacting physical variables that describe habitat. The central theme is the spatial coverage and fundamental granularity of such models. Despite a broad literature, there is a lack of documented examples of the application of hydraulic-habitat models through all stages in the environmental flow decision-making process. The review concludes with four short examples which illustrate the use of model output.

Increased fine sediment deposition and entrainment in rivers can arise from a combination of factors including low flows, habitat modification and excessive sediment delivery from the catchment. Physical and visual methods have traditionally been used to quantify the volume of deposited fine sediment (

Background: The purpose of the present study was to determine cobalt and chromium ion levels in the blood and urine of patients in whom a modern-generation metal-on-metal hip resurfacing device had been implanted. Methods: A total of ninety-seven patients with a Conserve Plus metal-on-metal hip resurfacing implant were followed prospectively for two years. Cobalt and chromium levels in erythrocytes, serum, and urine were measured preoperatively as well as three, six, twelve, and twenty-four months postoperatively. Results: The median serum cobalt and chromium ion levels were 1.04 μg/L (range, 0.31 to 7.42 μg/L) and 2.00 μg/L (range, 0.28 to 10.49 μg/L), respectively, at one year after surgery and 1.08 μg/L (range, 0.44 to 7.13 μg/L) and 1.64 μg/L (range, 0.47 to 10.95 μg/L), respectively, at two years after surgery. The corresponding mean levels (and standard deviations) of serum cobalt and chromium were 1.68 ± 1.66 μg/L and 2.70 ± 2.22 μg/L, respectively, at one year after surgery and 1.79 ± 1.66 μg/L and 2.70 ± 2.37 μg/L, respectively, at two years after surgery. Conclusions: These levels compare favorably with other published ion results for metal-on-metal hip resurfacing and replacement implants. No pseudotumors or other adverse soft-tissue reactions were encountered in our study population. Further research is needed to determine the clinical importance of increased cobalt and chromium ion levels in serum and urine following metal-on-metal hip resurfacing. Level of Evidence: Therapeutic Level IV. See Instructions to Authors for a complete description of levels of evidence.

The taxonomic resolution of macroinvertebrate community data needs careful consideration, to ensure that research objectives in pure and applied freshwater scientific research are met. The level of taxonomy used may be driven by time and financial restrictions associated with the increasing resources and effort needed to identify organisms to a lower taxonomic resolution. This paper aims to assess the influence of taxonomic resolution on the understanding of long-term (1985–2006) benthic macroinvertebrate community response to changes in the hydrological regime. There were marked differences in the number of taxa included in the analysis when comparing ‘species’- and ‘family’-level data used to derive lotic-invertebrate index for flow evaluation (LIFE) scores, particularly among species rich orders, such as Ephemeroptera, Plecoptera, Trichoptera and Coleoptera. The performance of the partial least squares (PLS) regression models of hydrological variables and the LIFE scores derived for different taxonomic levels were compared. Coefficients of determination were higher for species-level LIFE data than for the same data resolved to family level. Results demonstrate that the species-level LIFE data produced significant model components while those derived from family-level data were not; although both models indicated the dominance of hydrological indices quantifying the duration and magnitude of the hydrological events. We conclude that there is a growing need to resolve faunal data to species level to adequately fulfil operational and legislative obligations for river management and conservation purposes.

Background Total knee arthroplasty is a common treatment for severe knee osteoarthritis. Objective measures are needed to evaluate the effect of arthroplasty surgery on function and joint loading, in particular given the rise in younger adults receiving this intervention. The objective was to compare neuromuscular activation patterns of the knee musculature during level walking one-week prior to and one-year following total knee arthroplasty. Methods Surface electromyograms from seven periarticular muscles were recorded from 43 patients with severe medial compartment knee osteoarthritis during walking one-week prior to and one-year following total knee arthroplasty. Principal component analysis extracted patterns from the electromyographic waveforms and assigned scores for these patterns, which were statistically compared between test times and between medial and lateral sites within a muscle group. Findings Significantly lower overall activation amplitudes were found for the quadriceps and hamstrings, with decreased activity during mid-late stance following surgery. Significant increases in gastrocnemius activity were found late stance, along with altered waveform shapes. Interpretation In general, the post-surgical changes moved toward more typical asymptomatic patterns, supporting improved neuromuscular strategies during walking. Given that improvements would not be expected to occur naturally in severe osteoarthritic knees the positive changes in neuromuscular characteristics during specific phases of the gait cycle can be explained in part by the altered mechanical environment and reduction in pain from the surgical intervention. These objective findings are directly relevant to the joint loading environment and can be valuable for evaluating surgical techniques, different prostheses and pre–post surgical management.

The linkage of trait responses to stressor gradients has potential to expand biomonitoring approaches beyond traditional taxonomically based assessments that identify ecological effect to provide a causal diagnosis. Traits-based information may have several advantages over taxonomically based methods. These include providing mechanistic linkages of biotic responses to environmental conditions, consistent descriptors or metrics across broad spatial scales, more seasonal stability compared with taxonomic measures, and seamless integration of traits-based analysis into assessment programs. A traits-based biomonitoring approach does not require a new biomonitoring framework, because contemporary biomonitoring programs gather the basic site-by-species composition matrices required to link community data to the traits database. Impediments to the adoption of traits-based biomonitoring relate to the availability, consistency, and applicability of existing trait data. For example, traits generalizations among taxa across biogeographical regions are rare, and no consensus exists relative to the required taxonomic resolution and methodology for traits assessment. Similarly, we must determine if traits form suites that are related to particular stressor effects, and whether significant variation of traits occurs among allopatric populations. Finally, to realize the potential of traits-based approaches in biomonitoring, a concerted effort to standardize terminology is required, along with the establishment of protocols to ease the sharing and merging of broad, geographical trait information.

Background and purpose There is no standard for patient triage in total knee arthroplasty (TKA) based on joint functional characteristics. This is largely due to the lack of objective postoperative measurement of success in TKA in terms of function and longevity, and the lack of knowledge of preoperative metrics that influence outcome. We examined the association between the preoperative mechanical environment of the patients knee joint during gait and the post-TKA stability of the tibial component as measured with radiostereometric analysis (RSA). Methods 37 subjects were recruited out of a larger randomized RSA trial. 3-dimensional gait analysis was performed in the preoperative week. Longitudinal RSA data were gathered postoperatively at 6 months and 1 year. Results We found a statistically significant association between the pattern of the knee adduction moment during gait preoperatively and the total migration of the implant at 6 months postoperatively. A substantial proportion of the variability in the total postoperative tibial component migration (R2 = 0.45) was explained by a combination of implant type, preoperative knee joint loading patterns during gait, and body mass index at 6 months postoperatively. The relationships did not remain statistically significant at 1 year postoperatively. Interpretation Our findings support the hypothesis that preoperative functional characteristics of patients, and particularly joint loading patterns during activities of daily living, are important for outcome in TKA. This represents a first step in the development of predictive models of objective TKA outcome based on preoperative patient characteristics, which may lead to better treatment strategies. ClinicalTrials.gov (NCT00405379)

The PROFEMUR Z modular total hip arthroplasty component (Wright Medical Technology, Arlington, Tennessee) is a primary total hip replacement system that offers surgeons the ability to alter the length and version of the femoral neck after the femoral stem has been implanted. The modularity is achieved through taper interfaces at the distal and proximal ends of the femoral neck. The proximal femoral neck taper engages with the femoral head, and the distal taper engages with the femoral stem. In this report, we present the case of a patient who twice underwent total hip arthroplasty revision surgery. The first revision was due to a fractured ceramic femoral head. The second revision was due to a complete fracture of the modular femoral neck. This report will focus on the second revision, and, specifically, the failure of the modular femoral neck at the junction of the neck to the femoral stem. The patient was informed that data concerning the case would be submitted for publication, and he consented. A sixty-two-year-old man (height, 181 cm; weight, 84 kg; body mass index, 25.6 kg/m2) presented with severe primary osteoarthritis of the left hip. He underwent uneventful primary total hip replacement surgery in November 2006. The components implanted were a 58-mm Lineage cup fixed with two screws; a size-5 PROFEMUR Z modular stem with a modular, long, 8° retroverted neck; a 32-mm ceramic femoral head with a +3.5-mm offset; and a ceramic Transcend liner (Wright Medical Technology). The patient recovered well with no postoperative complications. In February 2007, the patient presented to the emergency department with a painful left hip. Radiographs revealed superior migration of the femoral head, and a fracture of the ceramic head was suspected. The patient was hospitalized, and revision total hip arthroplasty was performed. During the procedure, the head was found …

Aquatic vegetation plays a role in engineering river channels by altering patterns of flow velocity, sediment dynamics and, consequently, development and turnover of habitats. This could potentially aid in the rehabilitation of over-widened, straightened channels, and, less desirably, reduce channel conveyance and contribute to flooding problems. Therefore, it is important to understand the environmental conditions in which in-stream and marginal vegetation can reach sufficient abundance for these engineering roles to have a significant impact on the physical environment. Macrophyte and environmental data from 1653 river reaches across Great Britain were collated. Specific stream power (SSP) was calculated to represent hydrological disturbance and a median bed calibre index and percentage sand and finer sediment were used to characterize substrate size, since stream energy and sediment properties are two major physical controls on aquatic vegetatin. Correlation and Principal Component Analysis (PCA) revealed subtly different physical habitat ‘preferences’ between species of contrasting morphology. Correlations of additional environmental data with SSP indicated that this physical disturbance variable also reflects gradients in stress variables describing nutrient availability and latitude and so is a useful integrator of a number of important pressures on plant survival. A conceptual model was produced which indicates ranges of SSP which may determine the significance of aquatic macrophytes in channel engineering processes. This model could contribute to predicting the potential for macrophyte growth within a given reach thus indicating its capacity for self-restoration or the likelihood of weed problems.

Riparian vegetation, particularly trees and shrubs, can play a crucial role in the construction and turnover of fluvial landforms, but aquatic plants may also act as river ecosystem engineers. Macrophyte and environmental data from 467 British river reaches are used to explore associations between aquatic plant morphotypes and the physical characteristics of the reaches. The abundance of five plant morphotypes (mosses, linear-submerged, patch-submerged, linear emergent, branched emergent) is estimated for each river reach. Cluster analysis is applied to the abundances of the five morphotypes across the 467 reaches to identify six typical assemblages or clusters of the morphotypes. These clusters are found to be associated with statistically significantly different values of seven physical variables (altitude, slope, median annual flood discharge, channel width, mean bed sediment size, percentage cover of sand and silt on the river bed, and unit stream power). Associations between the morphotype clusters and combinations of the physical variables are explored using Canonical Correspondence Analysis and standard slope–discharge–sediment calibre–channel style graphs. Several of the morphotype clusters are discriminated by unit stream power and bed sediment size. In particular, morphotype clusters dominated by emergent and submerged macrophytes are associated with granules, sand, and finer bed sediments and are rarely found where unit stream power exceeds 100 W m − 2 . One cluster characterised by branched emergent species with relatively low cover of submerged morphotypes is confined to sites with unit stream power below 20 W m − 2 ; and another cluster characterised by linear emergents with low cover of submerged morphotypes is associated with particularly extensive, fine bed sediments, suggesting possible smothering of submerged plants. In contrast, mosses reach their highest abundance in two clusters associated with the highest unit stream power and coarsest bed sediments, with the patch-submerged morphotype reaching relatively high abundance in the slightly lower energy cluster of these two. British rivers have been modified over hundreds of years such that the sample of study reaches have predominantly single-thread channels. However, the plotting positions of these reaches on established graphs describing slope–discharge–sediment calibre–channel style associations, illustrates the potential of some of these sites to develop wandering or braided forms and, in lower energy situations, the potential for aquatic plants to trap fine sediments and contribute to landform building and channel change if maintenance (cutting and dredging) of the emergent and submerged morphotypes were reduced.

1. There is a need to relate changing river flows to ecological response, particularly using methods which do not require extensive new data for water bodies without historical data. This paper describes how local-scale habitat features and changing discharge appear to influence a macroinvertebrate-based biotic index. 2. The study used 87 time-series of river biomonitoring data from upland, wadeable streams with quasi-natural flow regimes across England and Wales. Twenty-seven of the sites were matched to a nearby flow gauging station, and historical, natural flows using a generalized rainfall-runoff model were synthesized for 60 sites. All sites were matched to a River Habitat Survey (RHS) within 1 km. 3. The data were analysed using multilevel linear regression, combining sample- and site-level characteristics as predictors. Common responses were assessed across sites, using the biotic index LIFE (Lotic Invertebrate index for Flow Evaluation), an average of abundance-weighted Flow Groups which indicate the relative preference among taxa for higher velocities with gravel/cobble substrates or slow velocities with finer substrates. The aim was to understand the influence of habitat on macroinvertebrate response to antecedent high and low flow magnitude. 4. There was a positive relationship between LIFE score calculated from spring and autumn samples and antecedent high (Q10) and low flows (Q95). The relationship between summer Q10 and autumn LIFE score was steeper than the relationship between winter Q10 and spring LIFE score. Bed and bank resectioning reduced overall LIFE and increased the steepness of the response of LIFE to low (Q95) flow. 6. The models derived may be used to guide environmental flow allocations and to quantify the relative influence of flow and physical habitat change on macroinvertebrate responses. The interaction between resectioning and low flow has particular implications for the conservation of macroinvertebrate taxa with requirements for faster flowing water.

1. Methods are needed to relate changing river flows to ecological response, particularly those which do not require collection of extensive new data for river segments that lack historical data. Using time-series of river biomonitoring data from wadeable lowland streams in Denmark and the East Midlands of the U.K., we describe how local-scale habitat features (indexed through River Habitat Survey or Danish Habitat Quality Survey) and changing river flow (discharge) influence the response of a macroinvertebrate community index. The approach has broad applicability in developing regional flow-ecological response models. 2. We analysed the data using multilevel linear regression, combining sample-level and site-level characteristics as predictors. We focused on the potential for common responses across sites; hence for each sample, the macroinvertebrate community was summarised into an index, Lotic Invertebrate index for Flow Evaluation (LIFE), an average of abundance-weighted flow groups which indicate the microhabitat preferences of each taxon for higher velocities and clean gravel ⁄cobble substrata or slow ⁄ still velocities and finer substrata. 3. For the Danish fauna, the LIFE score responded to three predictors in an additive manner: high flows in the preceding 4 months (positive), substratum composition and whether the channel was meandering or straight. The East Midlands fauna responded to three predictors: high and low flows in the preceding 6 months (positive) and the degree of resectioning of the channel (negative). In both cases, LIFE responded negatively to features associated with historical channel modification. We suggest that there are severalmechanisms for these relationships, including the narrower tolerances of taxa preferring high velocity habitat; these taxa are also continually recovering from extreme flow events over an inter-annual timescale. 4. At the East Midlands sites, there was an interaction between degree of resectioning and antecedent low flow. At sites with a greater extent of resectioning, the LIFE-discharge relationship was also steeper than at less modified sites. Consideration of the underlying data suggests that there are two mechanisms for this response. Firstly, in less modified sites, refugia are present during low flows for taxa preferring higher velocities such as riffle beetles, caseless caddis, mayflies and Gammarus pulex. Secondly, high flows are associated with decreasing abundances of taxa such as molluscs, flatworms and leeches at more resectioned sites, but with stable or increasing abundances at less modified sites. 5. The LIFE index responded to both antecedent flow and habitat modification in two separate data sets from lowland wadeable streams. This is the first time that the combined importance of these two factors has been demonstrated using routine invertebrate biomonitoring data. These results complement other site-specific studies that have shown how channel structure interacts with flow to create physical habitat, and should assist future work aiming to define flow-habitat-biota relationships. 6. The derived models may be used to help guide environmental flow allocations, for example by predicting the slope of response of LIFE score to flow for comparable new locations which lack biological data.

An in vitro radiostereometric analysis (RSA) phantom study of a total knee replacement was carried out to evaluate the effect of implementing two new modifications to the conventional RSA procedure: (i) adding a landmark of the tibial component as an implant marker and (ii) defining an implant-based coordinate system constructed from implant landmarks for the calculation of migration results. The motivation for these two modifications were (i) to improve the representation of the implant by the markers by including the stem tip marker which increases the marker distribution (ii) to recover clinical RSA study cases with insufficient numbers of markers visible in the implant polyethylene and (iii) to eliminate errors in migration calculations due to misalignment of the anatomical axes with the RSA global coordinate system. The translational and rotational phantom studies showed no loss of accuracy with the two new measurement methods. The RSA system employing these methods has a precision of better than 0.05 mm for translations and 0.03 degrees for rotations, and an accuracy of 0.05 mm for translations and 0.15 degrees for rotations. These results indicate that the new methods to improve the interpretability, relevance, and standardization of the results do not compromise precision and accuracy, and are suitable for application to clinical data.

Although the year 2020 is just over a decade away, changes in population demographics as well as advancements in knowledge, techniques, and treatments will likely lead to substantial changes in the delivery of orthopaedic care. One specific driver of the projected change is the fact that the North American population is aging. Projections show that, by 2020, 16.3% of the U.S. population and approximately 25% of the Canadian population will be sixty-five years of age or older, double the current number1,2. This has led to projections for an increased incidence and prevalence of age-related musculoskeletal conditions, such as fragility fractures and osteoarthritis3-8. Concurrent with the projections showing an increased need for orthopaedic services in 2020 is a projection showing a decreased number of full-time-equivalent orthopaedic surgeons, mostly due to retirement9. In light of these factors, a symposium was held, in June 2008, at the Combined Annual Meeting of the American Orthopaedic Association and the Canadian Orthopaedic Association in Quebec City to discuss the implications of an aging population and workforce, as well as changing disease patterns and treatment options, on core orthopaedic services in the year 2020. This article is a summary of that symposium and covers four specific aspects of orthopaedics in 2020: (1) pediatric orthopaedics, (2) fragility fractures, (3) hip and knee replacement surgery, and (4) care models for the delivery of orthopaedic services. ### Demographic Changes The projected population of children in North America over the next ten to twenty years is expected to remain relatively constant. However, the family circumstances of these children will change considerably3,4. More children will be single children, and their family trees will be vertical rather than horizontal, with many older relatives, fewer or no siblings, and fewer cousins (because their …

The possible effects of changing climate on a southern and a north-eastern English river (the Thames and the Yorkshire Ouse, respectively) were examined in relation to water and ecological quality throughout the food web. The CLASSIC hydrological model, driven by output from the Hadley Centre climate model (HadCM3), based on IPCC low and high CO2 emission scenarios for 2080 were used as the basis for the analysis. Compared to current conditions, the CLASSIC model predicted lower flows for both rivers, in all seasons except winter. Such an outcome would lead to longer residence times (by up to a month in the Thames), with nutrient, organic and biological contaminant concentrations elevated by 70–100% pro-rata, assuming sewage treatment effectiveness remains unchanged. Greater opportunities for phytoplankton growth will arise, and this may be significant in the Thames. Warmer winters and milder springs will favour riverine birds and increase the recruitment of many coarse fish species. However, warm, slow-flowing, shallower water would increase the incidence of fish diseases. These changing conditions would make southern UK rivers in general a less favourable habitat for some species of fish, such as the Atlantic salmon (Salmo salar). Accidental or deliberate, introductions of alien macrophytes and fish may change the range of species in the rivers. In some areas, it is possible that a concurrence of different pressures may give rise to the temporary loss of ecosystem services, such as providing acceptable quality water for humans and industry. An increasing demand for water in southern England due to an expanding population, a possibly reduced flow due to climate change, together with the Water Framework Directive obligation to maintain water quality, will put extreme pressure on river ecosystems, such as the Thames.

The EU water framework directive (WFD) provides a template for sustainable water management across Europe. The WFD requires the development of procedures to ensure appropriate mitigation of anthropogenic impacts on river ecosystems resulting from water abstraction and impoundments. It is widely acknowledged that alterations to flow regime impact on riverine ecosystems. As a result, hydromorphology, which includes the hydrological regime, is embedded within the WFD as a supporting element to achieve good ecological status (GES). Environmental flow releases from impoundments such as reservoir dams will need to be implemented to mitigate impacts from their construction and operation. This paper outlines the process involved in the analysis of available scientific information and the development of guidance criteria for the setting of environmental flow release regimes for UK rivers. The paper describes two methods—developed by round-table expert knowledge and discussions and supported by available data—for implementation of the WFD for rivers subject to impoundments. The first is a method for preliminary assessment of a water body to determine if it is likely to fail to achieve GES because of changes to the flow regime (indexed by simple flow regime statistics) in systems where appropriate biological assessment methods are limited or currently unavailable. The second is a method for defining an environmental flow regime release based on the requirements of riverine ecological communities and indicator organisms for basic elements (building blocks) of the natural flow regime.

Under the European Union Water Framework Directive, Member States must put in place a river basin planning framework to determine what measures are necessary to maintain and improve the ecological status for all surface water bodies. The governmental organisations legally responsible for implementing the Directive in the UK have recognised that an appropriate river flow regime is fundamental to maintain a healthy river and, as a result, they need to regulate abstractions and effluent discharges and ensure sufficient water is released from impoundments. This paper reports on the process of producing environmental standards that define the maximum abstraction allowable from UK rivers, to leave sufficient flow to maintain a healthy river ecosystem. As there are currently insufficient data available to determine the relationships between river flow and ecological status empirically, expert knowledge was captured through a series of workshops at which leading UK freshwater scientists defined maximum l...

Using a dataset of gauged river discharges taken from sites in England and Wales, we applied linear multilevel models, also known as mixed effects models, to quantify the variability in discharge and the discharge-hydraulic geometry relationships across three nested spatial scales. A jackknifing procedure was used to test the ability of the multilevel models to predict hydraulic geometry, and therefore width, mean depth and mean velocity, at ungauged stations. These models provide a framework for making predictions of hydraulic geometry parameters, with associated level of uncertainty, using different levels of data availability. Results indicate that as one travels downstream along a river there is greater variability in hydraulic geometry than is the case between rivers of similar sizes. This indicates that hydraulic geometry is driven by catchment area, and therefore hydrology, to a greater extent than by natural geomorphological variations in the streamwise direction such as changes in meso-habitat types and local channel engineering, but these geomorphological variations can still have a major impact on channel structure.

SummaryObjectiveTo test the hypothesis that an association exists between the characteristics of the knee adduction moment and foot progression angle (FPA) in asymptomatic individuals and those with mild to moderate and severe knee osteoarthritis (OA).DesignFifty asymptomatic individuals, 46 patients with mild to moderate and 44 patients with severe knee OA were recruited. Maximum knee adduction moment during late stance and principal component analysis (PCA) were used to describe the knee adduction moment captured during gait. Multiple regression models were used for each of the three group assignments to analyze the association between the independent variables and the knee adduction moment.ResultsFPA explained a significant amount of the variability associated with the shape of the knee adduction moment waveform for the asymptomatic and mild to moderate groups (P0.05). Walking velocity alone explained significant variance associated with the shape of the knee adduction moment in the severe OA group (P

We review the current status of knowledge regarding the role that flow parameters play in controlling the macrophyte communities of temperate lowland rivers. We consider both direct and indirect effects and the interaction with other factors known to control macrophyte communities. Knowledge gaps are identified and implications for the management of river systems considered. The main factors and processes controlling the status of macrophytes in lowland rivers are velocity (hence also discharge), light, substrate, competition, nutrient status and river management practices. We suggest that whilst the characteristics of any particular macrophyte community reflect the integral effects of a combination of the factors, fundamental importance can be attributed to the role of discharge and velocity in controlling instream macrophyte colonisation, establishment and persistence. Velocity and discharge also appear to control the relative influence of some of the other controlling factors. Despite the apparent importance of velocity in determining the status of macrophyte communities in lowland rivers, relatively little is understood about the nature of the processes controlling this relationship. Quantitative knowledge is particularly lacking. Consequently, the ability to predict macrophyte abundance and distribution in rivers is still limited. This is further complicated by the likely existence of feedback effects between the growth of macrophytes and velocity. Demand for water resources increases the pressure on lowland aquatic ecosystems. Despite growing recognition of the need to allocate water for the needs of instream biota, the inability to assess the flow requirements of macrophyte communities limits the scope to achieve this. This increases the likelihood of overexploitation of the water resource as other users, whose demands are quantifiable, are prioritised.

1. Invertebrate drift is commonly investigated in streams, with the majority of studies focussed on temporal (typically diel) variation. In comparison, few studies have investigated spatial variation in drift and there is little consensus among them. We tested the hypothesis that spatial variation in invertebrate drift is as important as temporal variation. 2. The density of drifting invertebrates in a chalk stream was sampled using an array of nets arranged to determine vertical, lateral and longitudinal variation. Samples were collected at dawn, during the day, at dusk and by night, on four separate monthly occasions. Insecta and Crustacea were analysed separately to identify the effect of differing life history strategies. The density of drifting debris was also recorded, to act as a null model. 3. Time of day and vertical position together explained the majority of the variance in invertebrate drift (79% for Insecta and 97% for Crustacea), with drift densities higher at dusk and night, and nearer the stream bed. Independently, time of day (38%, Insecta; 52%, Crustacea) and vertical position (41%, Insecta; 45%, Crustacea) explained a similar amount of the observed variance. Month explained some of the variance in insect drift (9%) but none for Crustacea. 4. Variation in the density of drifting debris showed little in common with invertebrate drift. There was little variation associated with time of day and only 27% of the observed variation in debris could be explained by the factors investigated here, with month explaining the largest proportion (20%). We suggest the difference in drifting debris and invertebrates provides further evidence for a strong behavioural component in invertebrate drift. 5. Spatial variation in invertebrate drift can be of the same order of magnitude as the much-described diel temporal variation. The extent of this spatial variation poses problems when attempting to quantify invertebrate drift and we recommend that spatial replication should be incorporated into drift studies.

Objectives:This report is a scoping review of the literature with the objective of identifying definitions, conceptual models and frameworks, as well as the methods and range of perspectives, for determining appropriateness in the context of healthcare delivery.Methods:To lay groundwork for future, intervention-specific research on appropriateness, this work was carried out as a scoping review of published literature since 1966. Two reviewers, with two screens using inclusion/exclusion criteria based on the objective, focused the research and articles chosen for review.Results:The first screen examined 2,829 abstracts/titles, with the second screen examining 124 full articles, leaving 37 articles deemed highly relevant for data extraction and interpretation. Appropriateness is defined largely in terms of net clinical benefit to the average patient and varies by service and setting. The most widely used method to assess appropriateness of healthcare services is the RAND/UCLA Model. There are many related concepts such as medical necessity and small-areas variation.Conclusions:A broader approach to determining appropriateness for healthcare interventions is possible and would involve clinical, patient and societal perspectives.

In many countries timely access to care is a growing problem. As medical costs escalate health care resources must be prioritized. In this context there is an increasing need for benchmarks and best practices in wait-time management. The Canadian Pain Society struck a Task Force in December 2005 to identify benchmarks for acceptable wait-times for treatment of chronic pain. As part of the mandate a systematic review of the literature regarding the relationship between waiting times, health status and health outcomes for patients awaiting treatment for chronic pain was undertaken. Twenty-four studies met the inclusion criteria for the review. The current review supports that patients experience a significant deterioration in health related quality of life and psychological well being while waiting for treatment for chronic pain during the 6 months from the time of referral to treatment. It is unknown at what point this deterioration begins as results from the 14 trials involving wait-times of 10 weeks or less yielded mixed results with wait-times amounting to as little as 5 weeks, associated with deterioration. It was concluded that wait-times for chronic pain treatment of 6 months or longer are medically unacceptable. Further study is necessary to determine at what stage the deterioration begins from the onset of pain to treatment and the impact of waiting on treatment outcomes. Most important is the need to improve access to appropriate care for patients with chronic pain, an escalating public health care problem with significant human and economic costs.

Mechanical factors have been implicated in the progression of knee osteoarthritis (OA). Understanding how these factors change as the condition progresses would elucidate their role and help in developing interventions that could delay the progress of knee OA. In this cross-sectional study, we identified kinematic and kinetic variables at the hip, knee, and ankle joints that change between three clinically distinct levels of knee OA disease severity: asymptomatic, moderate OA, and severe OA. The severity level was based on a combined radiographic/symptomatic clinical decision for treatment with (severe) or without (moderate) total knee replacement surgery. Gait variables that changed between groups were categorized as: those that differed between the asymptomatic group and both OA groups, those that differed between the asymptomatic group and the severe OA group only, or those that changed progressively, that is, the asymptomatic differed from the moderate OA, and the moderate OA differed from the severe OA group. Changes seen in both OA subject groups compared to asymptomatic included increased mid-stance knee adduction moments, decreased peak knee flexion moments, decreased peak hip adduction moments, and decreased peak hip extension moments. Changes found only in the severe knee OA group included multiple kinematic and kinetic differences at the hip, knee, and ankle joints. Gait differences that progressed with OA severity included decreased stance phase knee flexion angles, decreased early stance knee extension moments, decreased peak stance phase hip internal rotation moments, and decreased peak ankle dorsiflexion moments.

Background: Delirium is a common complication of hip fracture and is associated with negative outcomes. Previous studies document risk factors for post-operative delirium but have frequently excluded patients with pre-operative delirium. Objective: This study endeavours to document prevalence and risk factors for pre-operative delirium in hip fracture patients and compares risk factor profiles and outcomes between pre- and post-operative delirium. Methods: 283 hip fracture patients were assessed pre-operatively with the Delirium Elderly At Risk (DEAR) instrument, Mini-Mental State Examination (MMSE), and Confusion Assessment Method (CAM). They were followed on post-operative days 1, 3, and 5 for the presence of delirium. Doses of opioids were recorded. Wait time to surgery, length of stay, and discharge site were noted. Results: Delirium was present in 57.6% patients pre-operatively and 41.7% post-surgery. Not all patients (62%) with pre-operative delirium also had post-operative delirium. There was a considerable overlap in risk factors, with some differences. Wait time to surgery, number of comorbidities, and total pre-operative opioid and lorazepam doses were associated with pre- but not post-operative delirium. Negative outcomes were more closely associated with post-operative delirium. Conclusion: Delirium is common in pre-hip fracture surgery patients, and not all patients with pre-operative delirium go on to have post-operative delirium. Risk factor profiles are not identical, raising the possibility of identifying and intervening in patients at high risk of delirium pre-operatively.

Variability in morphologic features of the human lower extremity within and across populations has been reported, but limb asymmetry within individuals is often overlooked. For example, in 19 studies of version of the lower extremity in the literature, 6 document asymmetry in the population, but none of these reports document asymmetry in an individual. The aim of this study was to identify the (a)symmetry and quantify variability in the tibiae and femora of matched pairs of limbs. More specifically, using a computed tomography scan database tool, we (1) identified (a)symmetry between paired left and right legs for angulation, version, and alignment features and (2) calculated the percentage of paired limbs with1° of (a)symmetry for each evaluated parameter.Computerized axial tomographic scans (1.0 mm slices) from bilateral lower limbs of 361 skeletally mature subjects without bone pathology were prospectively acquired. Bones were segmented and morphologic features were measured.Angular features are symmetric left to right, but rotational features are not, with 7° of mean asymmetry in femoral anteversion (range: 0°-23°) and 3° of asymmetry in tibial version (range: 0°-8°).This study disproves the hypothesis that human limbs are absolutely symmetric, confirming instead that there is asymmetry in version between left and right paired limbs. Surgeons strive for symmetry in lower extremity reconstruction, and they often compare side to side in outcome studies, believing that normal limbs are absolutely symmetric when this is not necessarily true. These assumptions concerning lower extremity symmetry need to be reassessed.

Changes in water temperature can have important consequences for aquatic ecosystems, with some species being sensitive even to small shifts in temperature during some or all of their life cycle. While many studies report increasing regional and global air temperatures, evidence of changes in river water temperature has, thus far, been site specific and often from sites heavily influenced by human activities that themselves could lead to warming. Here we present a tiered assessment of changing river water temperature covering England and Wales with data from 2773 locations. We use novel statistical approaches to detect trends in irregularly sampled spot measurements taken between 1990 and 2006. During this 17-year period, on average, mean water temperature increased by 0.03 °C per year (±0.002 °C), and positive changes in water temperature were observed at 2385 (86%) sites. Examination of catchments where there has been limited human influence on hydrological response shows that changes in river flow have had little influence on these water temperature trends. In the absence of other systematic influences on water temperature, it is inferred that anthropogenically driven climate change is driving some of this trend in water temperature. © 2014 The Authors. Hydrological Processes published by John Wiley & Sons Ltd.

To assess fragment micromotion in three fracture fixation constructs 18 composite femur models were sectioned to create AO-C3 fractures and fixed using the Less Invasive Stabilization System (LISS), Dynamic Condylar Screw (DCS), or the Condylar Buttress Plate (CBP). Tantalum beads were attached to each fracture fragment. The constructs were tested for permanent deformation after cyclical loading (amplitude = 242.2N) and elastic deformation during static loading with 490.5N. Radiographs were taken before loading and then after unloading to determine permanent deformation or during loading to determine elastic deformation. We used RSA to quantify the six degrees of freedom interfragmentary maximum total motion, strain, and stress. For maximum total motion the CBP had more permanent deformation and two failures, whereas the LISS underwent the greatest elastic deformation. LISS and CBP had the highest strain conditions in the fracture gap and LISS had the greatest stress movements between fragments, all of which exceeded the upper limits for bone healing. LISS and CBP may not be indicated for comminuted fractures due to the high degree of flexibility of the LISS, resulting in high stress and strain conditions and susceptibility to catastrophic failure and high strain conditions with the CBP.

To assess the test–retest reliability of the EQ-5D-5L (5L) and compare the validity of the 5L and EQ-5D-3L (3L) in osteoarthritis patients referred to an orthopaedic surgeon for total joint replacement. We mailed questionnaires to 306 consecutive patients following referral and a second questionnaire after 2 weeks to assess reliability. Questionnaires included the 5L, EQ-VAS, Short Form-12, Oxford hip and knee scores, pain VAS, and the 3L. We compared the ceiling effect, redistribution properties, convergent and discriminant validity, and discriminatory power of the 5L and 3L. We obtained 176 respondents (response rate 58 %), 60 % female, 64 % knee patients, mean age 65 years (SD 11), with no significant differences between responders versus non-responders. Intraclass correlation coefficients were 0.61–0.77 for the 5L dimensions and 0.87 for the 5L index. For the 3L, most patients used level 2 (some/moderate problems) for mobility (87 %), usual activities (78 %), and pain/discomfort (71 %). In comparison, 5L responses were spread out with only 52, 42, and 50 %, respectively, using the middle level. All convergent validity coefficients were stronger with the 5L (Spearman coefficients 0.51–0.75). Absolute informativity (Shannon’s index) showed higher results for all dimensions of the 5L compared with the 3L (average difference 0.74). Relative informativity (Shannon’s evenness index) showed an increase from the 3L to the 5L in mobility, usual activities, and pain/discomfort. The 5L provided stronger validity evidence than the 3L, especially for dimensions relevant to this patient population—mobility, usual activities, and pain/discomfort.

This paper describes a physically based three-dimensional bioenergetic model for prediction of physical habitat quality for drift-feeding juvenile salmonids in a river. A three-dimensional Computational Fluid Dynamics (3D-CFD) model is used to simulate hydraulic patterns in a 50 m reach of the Bere stream, Dorset, UK. This information is then combined with a bioenergetic model that uses behavioural and physiological relationships to quantify the spatial pattern of energy gain when drift feeding. The model was tested by comparing patterns of predicted energy intake with observed habitat use by juvenile salmonids at different times of day. Hydraulic measurements or predictions are required as input to bioenergetic models to calculate the foraging range of the fish. Horizontal and vertical velocity gradients can be high and variable in shallow streams with complex topography and roughness zones. In this paper, a three-dimensional hydraulic model enables more realistic calculation of the foraging area of the fish. This takes account of the complexity of horizontal and vertical velocity gradients. Numerical experiments are used to demonstrate the sensitivity of energetic gain to changes in the method of calculating foraging area. Results support the hypothesis that feeding fish preferentially select areas of high energy gain, but move to areas of lower velocity when resting.

River corridors in urban environments provide areas of biodiversity which are important for both aesthetic and economic reasons. A physical habitat model, which was used to assess urban rivers in Birmingham, UK, was applied to pairs of selected reaches to represent differing levels of habitat diversity on three rivers. The results for different life-stages of dace, roach and chub suggest that the worst physical habitat occurs in highly modified channels and at the highest flows. Four scenarios, which were designed to represent alterations in flow regime caused by changes in management practices, were calculated using the hydrological model. Changes in physical habitat created by changes to the flow regime were assessed using a consistent, replicable method. It was shown that an increase in runoff would have detrimental effects in all cases, and that less engineered sites would benefit more from flow reductions. The lack of a suitable habitat for fry is shown to be a limiting factor for fish at all sites.

This study compared the midterm results between press-fit and cemented implantation of a highly congruent, all-polyethylene patellar component. We followed prospectively 172 implants (cemented, n = 133; press-fit, n = 39). Average follow up was 6 years (range, 5-8 years). Patellofemoral complications occurred in 4 cemented patellae (2.3%). Two of these patellae required revision. Cemented implants had a significantly higher incidence of patellar maltracking (30% vs 8%; P= .005). No significant differences in the overall Knee Society scores (mean, 165; SD, 27) or any of its components relevant to patellofemoral function were detected between fixation methods. A retrieved specimen showed an intervening fibrous membrane at the implant-bone interface. The potential for macrophage-mediated osteolysis at this site is unknown. No other adverse outcome was associated with press-fit implantation. These results suggest that at midterm follow-up, press-fit implantation of this all-polyethylene patellar component may improve tracking and represents a viable alternative to cement fixation.

Two hypotheses were offered for the effect of shorter hospital stays on mortality after hip fracture surgery: worsening the quality of care and shifting death occurrence to postacute settings.We tested whether the risk of hospital death after hip fracture surgery differed across years when postoperative stays shortened, and whether care factors moderated the association.Analysis of acute hospital discharge abstracts for subgroups defined by hospital type, bed capacity, surgical volume, and admission time.153,917 patients 65 years or older surgically treated for first hip fracture.Risk of hospital death.We found a decrease in the 30-day risk of hospital death from 7.0% (95%CI: 6.6-7.5) in 2004 to 5.4% (95%CI: 5.0-5.7) in 2012, with an adjusted odds ratio [OR] 0.71 (95%CI: 0.63-0.80). In subgroup analysis, only large community hospitals showed the reduction of ORs by calendar year. No trend was observed in teaching and medium community hospitals. By 2012, the risk of death in large higher volume community hospitals was 34% lower for weekend admissions, OR = 0.66 (95%CI: 0.46-0.95) and 39% lower for weekday admissions, OR = 0.61 (95%CI: 0.40-0.91), compared to 2004. In large lower volume community hospitals, the 2012 risk was 56% lower for weekend admissions, OR = 0.44 (95%CI: 0.26-0.75), compared to 2004.The risk of hospital death after hip fracture surgery decreased only in large community hospitals, despite universal shortening of hospital stays. This supports the concern of worsening the quality of hip fracture care due to shorter stays.

Background: Total hip and knee arthroplasty (THA and TKA) are accessible to patients with end-stage hip and knee arthritis in most health care systems. The availability of total ankle arthroplasty (TAA) to patients with end-stage ankle arthritis is often restricted because of prosthesis cost. Ankle fusion (AF) is often offered as the only alternative. Patients should have equal access to procedures that are equivalent in total cost. We compared total costs of TAA, AF, THA, and TKA for similar cohorts in a government-funded teaching hospital. Methods: A subset of 13 TAA and 13 AF patients were selected from the Canadian Orthopaedic Foot and Ankle Society Prospective Ankle Reconstruction Database, and 13 THA and 13 TKA patients were randomly selected from the Canadian Joint Replacement Registry. Total cost was estimated from operating room time, hospital stay, surgeon billing, and equipment used. Results: Mean total cost associated with TAA was $13,500 ± 1000 and was the same as THA ($14,500 ± 1500) and TKA ($12,500 ± 1000). Mean total cost associated with AF was significantly less at $5500 ± 500. Mean operating room time was longer, but mean hospital stay was shorter for the ankle procedures compared with THA and TKA. Conclusion: All arthroplasties had similar total costs. Total ankle arthroplasty should not be denied based on prosthetic cost alone, as total procedure cost is equivalent to THA and TKA. We believe ankle fusion is a less expensive and preferable alternative for some patient groups. Level of Evidence: Level II, comparative series.

The excellent outcomes of total knee replacement (TKR) are compromised by a small proportion of patients who are dissatisfied with the outcome of their procedure.[1][1]-[5][2] Efforts have been made at every level of the patient pathway in order to improve the situation.[6][3]-[9][4] These include

Study Design Computer simulation to detect intervertebral motion enabling future follow-up of spinal fusions performed on patients with multilevel thoracic scoliosis. Objectives To propose a method using computer simulation to evaluate a radiostereometric analysis (RSA) marker placement protocol for visibility and redundancy and validate the performance of the developed RSA system in detecting intervertebral motion. Summary of Background Data Radiostereometric analysis is a stereo x-ray technique in which clusters of tantalum markers are implanted to label well-defined landmarks and measure the relative motion between rigid bodies. Methods A model of the spine with the instrumentation and the RSA markers was developed. The vertebrae were aligned to mimic multilevel thoracic scoliosis after correction. The researchers performed virtual segment motion to validate the performance of the developed system. X-ray images were simulated and RSA was used to evaluate the proposed marker placement protocol and detect virtual motion. The authors performed a physical phantom study to evaluate marker visibility. Results All markers were located and matched between simulations and the condition numbers were well below the recommended value of 100. Based on computer simulation, average translational accuracy was 0.14, 0.01, and 0.24 mm along the x , y , and z axes, respectively, and average rotational accuracy was 0.23°, 0.12°, and 0.11° about the x , y , and z axes, respectively. The translational and rotational precision of the simulated RSA system was generally high. The physical phantom study agreed with the computer simulation and validated marker visibility. Conclusions Computer simulation is a powerful tool that can be used to facilitate the development and refinement of an RSA system before its application in patients, particularly when the anatomy involved is complex. The proposed marker placement protocol yielded translational and rotational accuracy below the limits of clinical significance, which enables future follow-up of multilevel thoracic scoliosis with Lenke classification 1AN.

Physical habitat is important in determining the carrying capacity of juvenile brown trout, and within freshwater management. Summer daytime physical habitat selection for the parr lifestage (7–20 cm) juvenile brown trout (Salmo trutta) was assessed in 6 small lowland streams. Habitat preference was determined for the four variables; water velocity, water depth, substrate and cover, and the preferences for physical habitat selection were expressed in terms of habitat suitability indices (HSI’s). The statistical confidence of HSI’s was evaluated using power analysis. It was found that a minimum of 22 fish observations was needed to have statistical confidence in the HSIs for water depth, and a minimum of 92 fish observations for water velocity during daytime summer conditions. Generally parr were utilising the deeper habitats, indicating preference for deeper water. Cover was also being selected for at all sites, but selection was inconsistent among sites for the variables substrate and velocity. The results indicate that during daytime summer conditions water depth is a significant variable for parr habitat selection in these small lowland streams, with cover also being important. Therefore, daytime refugia may be a critical limiting factor for parr in small lowland streams, and important for stream management actions under the Water Framework Directive.

The future of total knee arthroplasty (TKA) surgery will involve planning that incorporates more patient-specific characteristics. Despite known biological, morphological, and functional differences between men and women, there has been little investigation into knee joint biomechanical and neuromuscular differences between men and women with osteoarthritis, and none that have examined sex-specific biomechanical and neuromuscular responses to TKA surgery. The objective of this study was to examine sex-associated differences in knee kinematics, kinetics and neuromuscular patterns during gait before and after TKA. Fifty-two patients with end-stage knee OA (28 women, 24 men) underwent gait and neuromuscular analysis within the week prior to and one year after surgery. A number of sex-specific differences were identified which suggest a different manifestation of end-stage knee OA between the sexes.

Surgical navigation systems for total knee arthroplasty (TKA) surgery are capable of capturing passive three-dimensional (3D) angular joint movement patterns intraoperatively. Improved understanding of patient-specific knee kinematic changes between pre and post-implant states and their relationship with post-operative function may be important in optimizing TKA outcomes. However, a comprehensive characterization of the variability among patients has yet to be investigated. The objective of this study was to characterize the variability within frontal plane joint movement patterns intraoperatively during a passive knee flexion exercise. Three hundred and forty patients with severe knee osteoarthritis (OA) received a primary TKA using a navigation system. Passive kinematics were captured prior to (pre-implant), and after prosthesis insertion (post-implant). Principal component analysis (PCA) was used to capture characteristic patterns of knee angle kinematics among patients, to identify potential patient subgroups based on these patterns, and to examine the subgroup-specific changes in these patterns between pre- and post-implant states. The first four extracted patterns explained 99.9% of the diversity within the frontal plane angle patterns among the patients. Post-implant, the magnitude of the frontal plane angle shifted toward a neutral mechanical axis in all phenotypes, yet subtle pattern (shape of curvature) features of the pre-implant state persisted.

Objective: Recent research has linked perceptions of injustice to problematic recovery outcomes for individuals with musculoskeletal injuries. However, the measure currently used to assess perceived injustice is not readily applicable to individuals who have a pain condition, such as osteoarthritis (OA), where pain onset is insidious as opposed to traumatic. The purpose of this study was to validate a modified version of the Injustice Experiences Questionnaire (IEQ-chr) for patients with OA of the knee. Methods: The IEQ-chr was administered along with measures of pain catastrophizing, fear of movement, depressive symptoms, pain severity and physical function to 110 individuals with severe OA of the knee. Results: Principal component analyses yielded a factor structure similar to that in the original validation study. The IEQ-chr had high internal consistency (Chronbach alpha=0.88), and was significantly correlated with pain catastrophizing, fear of movement, depressive symptoms, pain severity and physical function. Regression analyses revealed that the IEQ-chr contributed significant unique variance to prediction of pain severity and physical function, beyond the variance accounted for by measures of pain catastrophizing and fear of movement. Conclusions: The findings of the present study support the construct validity of the IEQ-chr in the context of osteoarthritis, and suggest that this measure may be useful in psychosocial assessment of individuals at risk for adverse pain outcomes. The discussion addresses theoretical and clinical implications of these findings.

Background:We previously reported our two and five-year results of arthroplasty with the Porous Coated Anatomic total hip prosthesis. We now report on the performance of this prosthesis at ten to fourteen years.Methods:The results of 311 total hip replacements in which a Porous Coated Anatomic prost

Quantitative physical habitat modelling is a river management methodology that has been developed to aid the assessment of the impacts of altered river discharge on freshwater aquatic communities. In this paper we outline the potential value of habitat modelling in advancing the study of fish (particularly 0+ fish) habitat use, and also issues surrounding the inclusion of young fish in environmental impact assessments. Young fish have often been used as target species during such assessments, due to their perceived sensitivity to environmental changes, particularly associated with altered river discharge. However in the past, the paucity of information on young life stages, combined with the general difficulty in quantifying their habitat requirements has limited the use of habitat models for this purpose. Firstly we describe the context within which habitat modelling has been applied traditionally: the development of water resources, and the predictive assessment of associated environmental problems. Alternative approaches to habitat modelling are briefly mentioned. Overall, these techniques, which combine physical and biological data offer a broad perspective for the ecological management of degraded rivers, and can assist in developing our understanding of the processes that influence aquatic organisms in running waters. In the 20 or so years since its inception, habitat modelling has undergone considerable improvement. However there has not been a recent review of such advances. Therefore in the main text, we describe the current state of habitat modelling, emphasising recent developments. Many of these offer possibilities for the advancement of our knowledge of 0+ fish.

Outcome questionnaires are increasingly being established as a validated mode of acquiring unbiased information on the results after health interventions. Using an assortment of questionnaires, distributed by mail to 27 372 and to a subgroup of 3 600 patients on file in the Swedish Knee Arthroplasty register (SKAR), relevant questionnaires were found to represent a feasable means of acquiring information regarding these elderly patients in a cross-sectional design. In the process, one of the questionnaires, the Oxford-12-item score, was translated and validated into Swedish. On balance, using parameters like patient burden, feasability, content validity and reliability, the SF-12 and the Oxford-12 ranked as the most appropriate general and disease specific questionnaire, respectively, in the context of the SKAR . Even a global single-item questionnaire, however, can yield usable information. Over-all response rates were generally high, in the order of 90%, higher for the shorter questionnaires. Satisfaction was primarily linked to the absence of pain. All questionnaires, both general health as well as knee specific ones, were found to be highly susceptible to bias by patient co-morbidity. Hence, even the single question of ”how does your knee feel”, proved influenced by, say, heart aches. For some questionnaires, the scores were biased by more than 100%. Preoperative WOMAC scores were shown to be predictive of the postoperative outcome. (Less)

The Canadian Joint Replacement Registry (CJRR) was launched in 2000 through the collaborative efforts of the Canadian Orthopedic Association and the Canadian Institutes for Health Information. Participation is voluntary, and data collected by participating surgeons in the operating room is linked to hospital stay information from administrative databases to compile yearly reports. In the fiscal year 2006–2007, there were 62,196 hospitalizations for hip and knee replacements in Canada, excluding Quebec. This represents a 10-year increase of 101% and a 1-year increase of 6%. Compared to men, Canadian women have higher age-adjusted rates per 105 for both TKA (148 vs. 110) and THA (86 vs. 76). There also exist substantial inter-provincial variations in both age-adjusted rates of arthroplasty and implant utilization that cannot be explained entirely on the basis of differing patient demographics. The reasons for these variations are unclear, but probably represent such factors as differences in provincial health expenditure, efforts to reduce waiting lists, and surgeon preference. The main challenge currently facing the CJRR is to increase procedure capture to > 90%. This is being pursued through a combination of efforts including simplification of the consent process, streamlining of the data collection form, and the production of customized reports with information that has direct clinical relevance for surgeons and administrators. As the CJRR continues to mature, we are optimistic that it will provide clinically important information on the wide range of factors that affect arthroplasty outcome.

The Oxford-12 Item Knee Score is a recently developed and validated patient-completed outcome measure designed specifically for use with knee arthroplasty in the United Kingdom. We have translated this questionnaire into Swedish and tested the validity and reliability of the translated version in a cross-sectional study by a postal survey to 1,200 randomly selected patients from the Swedish Knee Arthroplasty Register. Swedish versions of the WOMAC, Nottingham Health Profile, SF-36, SF-12, and the Sickness Impact Profile were employed in the validation process. We also tested feasibility and patient-burden parameters. The translated version appeared to be linguistically and culturally equivalent to the original version with good validity and reliability. Indirect measures of responsiveness indicated that it is at least as responsive to relevant knee arthroplasty patient states as the previously validated Swedish version of the WOMAC. Application of the translated questionnaire to this population is feasible with minimal imposed patient-burden. The Swedish translation of the Oxford-12 Item Knee Score is a valid and reliable tool for outcome studies on knee arthroplasty patients.

During a validation process of the Swedish Knee Arthroplasty Register (SKAR), living registered patients were sent a questionnaire to ask if they had been reoperated on. This gave an opportunity to pose a simple four-point question with respect to patient satisfaction which 95% of patients answered. We analyzed the answers of patients operated on between 1981 and 1995 and found that only 8% of the patients were dissatisfied regarding their knee arthroplasty 2-17 years postoperatively. The satisfaction rate was constant, regardless of when the operation had been performed during the 15-year period. The proportion of satisfied patients was affected by the preoperative diagnosis, patients operated on for a long-standing disease more often being satisfied than those with a short disease-duration. There was no difference in proportions of satisfied patients, whether they had primarily been operated on with a total knee arthroplasty (TKA) or a medial unicompartmental arthroplasty (UKA). For TKAs performed with primary patellar resurfacing, there was a higher ratio of satisfied patients than for TKAs not resurfaced, but this increased ratio diminished with time passed since the primary operation. Unrevised knees had a higher proportion of satisfied patients than knees that had been subject to revision, and among patients revised for medial UKA, the proportion of satisfied patients was higher than among patients revised for TKA. We conclude that satisfaction after knee arthroplasty is stable and long-lasting in unrevised cases and that even after revision most patients are satisfied.

By combining data from the Swedish Knee Arthroplasty Register and Swedish census registers we have calculated the past age-specific incidence of primary knee arthroplasties and predicted the demand. During the last 20 years, osteoarthrosis has accounted for the largest increase in number of knee arthroplasties while operations for rheumatoid arthritis remained constant. The mean yearly number of operations between the periods 1976-1980 and 1996-1997 increased more than five-fold, while only 6% of that increase could be explained by changes in the age-profile of the population. Most operations were performed on persons of 65 years and older who also had the largest increase in incidence. By using the incidences for 1996 and 1997 and taking into account the expected future changes in the age profile of the Swedish population, we estimate that, in the absence of an effective preventive treatment, the number of knee arthroplasties will increase by at least one third until 2030.

The Instream Flow Incremental Methodology (IFIM) using the Physical Habitat Simulation (PHABSIM) system, has seen increasing application to the assessment of changes in aquatic habitats in the UK over the last 10 years. In particular, the model has been applied operationally to chalk streams (e.g. the Rivers Allen and Piddle) in southern England for the alleviation of low ¯ow (ALF) problems. More recently, the model has also been used to examine the e�ect of changes in channel morphology upon aquatic habitats, such as those that occur during ¯ood defence, or river channel restoration, schemes. The paper outlines some of the issues related to the application of the model to groundwater dominated rivers, such as chalk streams, and provides examples of the application of the model to a water resource issue and to assess a habitat restoration scheme. The paper also reports on three areas of recent research to improve the methodology: (1) choice of representative study sites and habitat variation at the reach and sector scale; (2) modelling of time series and interpretation of alternativewater management regimes; and (3) the development of rapid assessment techniques based upon the transfer of standardised relationships between available habitat and discharge.