Metal on metal hip resurfacing arthroplasty: Where are we now?

Metal on metal hip resurfacing arthroplasty (HRA) was introduced in an attempt to address potential limitations regarding return to sport, return to high functional activity and premature wear in young patients requiring standard total hip replacement (THR). Around 12% patients undergoing hip replacement surgery are under 55 years of age. By more closely mimicking natural anatomy, and having a metal on metal (MoM) bearing, it was hoped that HRA would address the issues. However, concern has emerged about early failure, high revision rates from local adverse reactions to metallic wear debris and potential systemic consequences of metal ion cardiotoxicity. In this article, we discuss the existing literature in the field, the current clinical evidence surrounding HRA, its indications, clinical outcomes, and risk factors for failure and conclude if it still has a role within orthopaedic hip surgery.

Global Research Alliance N2 O chamber methodology guidelines: Recommendations for air sample collection, storage, and analysis.

Certain aspects in the collection, handling, storage, and subsequent analysis of discrete air samples from non-steady-state flux chambers are critical to generating accurate and unbiased estimates of nitrous oxide (N2 O) fluxes. The focus of this paper is on air sample collection and storage in small vials (<12 ml) primarily for gas chromatography (GC) analysis. Sample integrity is assured through following simple procedures including storage under pressure and analysis within a few months of collection. Concurrent storage of standards in an identical manner to samples is recommended and allows the storage period to be reliably extended. In the laboratory, an autosampler is typically used in batch analysis of ∼200 sequentially analyzed samples by GC with an electron capture detector (ECD). Some comparisons are given between GC and alternatives including optical N2 O detectors that are increasingly being used for high-precision N2 O measurement. The importance of calibration and traceability of gas standards is discussed, where high-quality standards ensure the most accurate assessment of N2 O concentration and comparability between laboratories. The calibration allows a consistent and best estimate of flux to be derived.

A hydrochemically guided landscape classification system for modelling spatial variation in multiple water quality indices: Process-attribute mapping.

Spatial variation in landscape attributes can account for much of the variability in water quality relative to land use on its own. Such variation results from the coupling between the dominant processes governing water quality, namely hydrological, redox, and weathering and gradients in key landscape attributes, such as topography, geology, and soil drainage. Despite the importance of 'process-attribute' gradients (PAG), few water quality models explicitly account for their influence. Here a processes-based water quality modelling framework is presented that more completely accounts for the role of landscape variability over water quality - Process-Attribute Mapping (PoAM). Critically, hydrochemical measures form the basis for the identification and mapping of effective landscape attributes, producing PAG maps that attempt to replicate the natural landscape gradients governing each dominant process. Application to the province of Southland (31,824 km2), New Zealand, utilised 12 existing geospatial datasets and a total of 28,626 surface water, groundwater, spring, soil water, and precipitation analyses to guide the identification and mapping of 11 individual PAG. The ability of PAGs to replicate regional hydrological, redox, and weathering gradients was assessed on the accuracy with which the hydrochemical indicators of each dominant process (e.g. hydrological tracers, redox indicators) were estimated across 93 long-term surface water monitoring sites (cross-validated R2 values of 0.75-0.95). Given hydrochemical evidence that PAGs replicate actual landscape gradients governing the dominant processes, they were combined with a land use intensity layer and used to estimate steady-state surface water quality. Cross-validated R2 values ranged between 0.81 and 0.92 for median total nitrogen, total oxidised nitrogen, total phosphorus and dissolved reactive phosphorus. Models of particulate species E. coli and total suspended sediment, although reasonable (R2 0.72-0.73), were less accurate, suggesting finer-grained land use, landscape attribute, and/or flow normalised measures are required to improve estimation.

Survivorship and long-term outcome of a consecutive series of 200 Scandinavian Total Ankle Replacement (STAR) implants.

AIMS: We report the long-term clinical and radiological outcomes of a consecutive series of 200 total ankle arthroplasties (TAAs, 184 patients) at a single centre using the Scandinavian Total Ankle Replacement (STAR) implants. PATIENTS AND METHODS: Between November 1993 and February 2000, 200 consecutive STAR prostheses were implanted in 184 patients by a single surgeon. Demographic and clinical data were collected prospectively and the last available status was recorded for further survival analysis. All surviving patients underwent regular clinical and radiological review. Pain and function were assessed using the American Orthopaedic Foot and Ankle Society (AOFAS) hindfoot scoring system. The principal endpoint of the study was failure of the implant requiring revision of one or all of the components. Kaplan-Meier survival curves were generated with 95% confidence intervals and the rate of failure calculated for each year. RESULTS: A total of 84 patients (87 ankles) were alive by the end of this study. Of the surviving 84 patients (87 ankles; rheumatoid arthritis (RA), n = 40; OA, n = 47), 45 were women and 39 were men, with a mean age of 54 years (18 to 72 years) at the time of surgery. A total of 32 implants failed (16%), requiring revision surgery. The mean time to revision was 80 months (2 to 257). The implant survival at 15.8 years, using revision as an endpoint, was 76.16% (95% confidence interval (CI) 64.41 to 87.91). We found a steady but low decrease in survival over the study period. The mean AOFAS score improved from 28 (10 to 52) preoperatively to 61 (20 to 90) at long-term follow-up. CONCLUSION: STAR prostheses in the United Kingdom have now been largely superseded by newer design TAAs, potentially with improved characteristics and surgical techniques. The long-term survivorship for the STAR prosthesis can provide a benchmark for these later designs of ankle arthroplasty.

Total ankle arthroplasty: what are the risks?: a guide to surgical consent and a review of the literature.

AIMS: Total ankle arthroplasty (TAA) surgery is complex and attracts a wide variety of complications. The literature lacks consistency in reporting adverse events and complications. The aim of this article is to provide a comprehensive analysis of each of these complications from a literature review, and to compare them with rates from our Unit, to aid clinicians with the process of informed consent. PATIENTS AND METHODS: A total of 278 consecutive total ankle arthroplasties (251 patients), performed by four surgeons over a six-year period in Wrightington Hospital (Wigan, United Kingdom) were prospectively reviewed. There were 143 men and 108 women with a mean age of 64 years (41 to 86). The data were recorded on each follow-up visit. Any complications either during initial hospital stay or subsequently reported on follow-ups were recorded, investigated, monitored, and treated as warranted. Literature search included the studies reporting the outcomes and complications of TAA implants. RESULTS: There were wound-healing problems in nine ankles (3.2%), superficial infection in 20 ankles (7.2%), and deep infection in six ankles (2.2%). Intraoperative fractures occurred in medial malleoli in 27 ankles (9.7%) and in lateral malleoli in four ankles (1.4%). Aseptic loosening and osteolysis were seen 16 ankles (5.8%). Fracture of the polyethylene component occurred in one ankle (0.4%) and edge-loading in seven ankles (2.5%). We observed medial gutter pain in 31 ankles (11.1%). The incidence of thromboembolism occurred in two ankles (0.7%). The results were found to be comparable to the previously reported complications of total ankle arthroplasty in the literature. CONCLUSION: Total ankle arthroplasty continues to evolve and improve the ankle function. Despite high overall complication rates with TAA surgery, most complications appear to be minor and do not affect final clinical outcome. Our results and literature review will help in the consent process and provide detailed complication rates for an informed consent. Cite this article: Bone Joint J 2018;100-B:1352-8.

Vertical stratification of redox conditions, denitrification and recharge in shallow groundwater on a volcanic hillslope containing relict organic matter.

Natural denitrification in groundwater systems has been recognised as an ecosystem service that reduces the impact of agriculturally-derived nitrate inputs to surface waters. Identification of this ecosystem service within the landscape would permit spatially differentiated land management and legislation. However, spatial variation in groundwater redox conditions poses a significant challenge to such a concept. To gain understanding of the small-scale mosaic of biogeochemical and hydrological controls on denitrification, we established a well field consisting of 11 multilevel well (MLW) clusters on a hillslope containing relict organic matter buried by volcanic deposits 1.8 ka before present. Based on site-specific redox classification thresholds, vertical redox gradients and denitrification potentials were detected at 7 of the 11 sites. Palaeosols or woody debris, which had previously been identified in laboratory experiments as resident electron donors fuelling denitrification, were visually recognisable at 4 of the 7 MLW sites with vertical redox gradients. Moderately enhanced groundwater dissolved organic carbon (DOC) concentrations occurred where resident electron donors were evident. DOC concentrations were lower where anoxic and nitrate-depleted groundwater was found but with an absence of resident electron donors. In these instances, it was assumed that nitrate reduction had occurred somewhere upgradient of the sampled well screen along the lateral groundwater flow path, with the proximate electron donor (DOC) largely consumed in the process, since no evidence was found for denitrification being fuelled by inorganic electron donors. Due to high variability in the isotopic signature of nitrate in oxidised groundwater, the nitrate dual isotope method did not yield firm evidence for denitrification. However, realistic vertical patterns were obtained using the excess N2 method. Tritium-based age dating revealed that oxic conditions were restricted to young groundwater (mean residence time ≤ 3 y), while anoxic conditions were observed across a wider age range (3-25 y).

The potential of L. scoparium, K. robusta and P. radiata to mitigate N-losses in silvopastural systems.

Silvopastoral systems aim to enhance economic, cultural and social principles by sustainably combining forest management with agriculture. In these typically high-nitrogen (N) environments, plant species selection can profoundly influence N fluxes. For grazed pastures, plants may be exposed to urine patches that have received the equivalent of up to 1000 kg N ha-1. We aimed to determine the growth and N fluxes in three potential trees that may be used in silvopastoral systems: L. scoparium, K. robusta and P. radiata. Plants were grown in a greenhouse lysimeter experiment, with controlled irrigation and temperature and exposed to N at rates of 200 kg ha-1 equiv. for 15 weeks, followed by the addition of 800 kg ha-1 N equiv, to simulate a urine patch. Urea produced a positive growth response of all plant species. Treatments containing L. scoparium and K. robusta leached lower amounts of nitrate (NO3-) (2 kg ha-1 NO3-) compared to P. radiata (53 kg ha-1). Measurements of N2O over 20 days after the application of 800 kg N ha-1 indicated an inhibitory effect of L. scoparium and K. robusta on denitrification, hence loss of N via N2O. Both L. scoparium and K. robusta demonstrated that they have potential to reduce N-losses in silvopastural systems, while producing valuable biomass.

Spinal anaesthesia with adjunctive intrathecal morphine versus continuous lumbar plexus blockade: a randomised comparison for analgesia after hip replacement.

Following elective total hip replacement, both continuous lumbar plexus blockade and spinal anaesthesia (with adjunctive intrathecal morphine) have shown early outcome benefits over opioid analgesia and single-injection nerve block. However, the two techniques have not been compared in a prospective randomised manner. Our study examined 50 patients undergoing elective hip joint replacement who were randomised to receive spinal anaesthesia (with adjunctive intrathecal morphine 0.1 mg) or patient-controlled continuous lumbar plexus blockade. All surgery was conducted under general anaesthesia. Measured outcomes included numerically rated postoperative pain, supplemental opioid consumption and indices of mobilisation together with complications. Results show that block placement time was marginally shorter for the spinal group (5 versus 7 minutes, P=0.01). The primary outcome, worst pain on movement/mobilisation during the first 24 hours, was not statistically significantly different between groups. Patients in the lumbar plexus group were given more intraoperative opioid and rescue morphine in the post-anaesthesia care unit (median = 4 versus 0 mg, P <0.001), with correspondingly higher pain scores (median 5/10 versus 0/10, P <0.001). Pain scores during the subsequent 24 hours were similar between groups, but more patients in the spinal group were given rescue morphine (5 versus 0, P=0.02). Physiotherapy mobilisation indices appeared similar between groups. More spinal group patients reported pruritus (12 versus 5, P=0.01), but antiemetic requirements, episodes of disorientation, arterial oxygen desaturation and falls were all similar between groups. Postoperative symptoms suggestive of neurological irritation or injury did not differ between groups. We found that following elective hip joint replacement, compared to continuous lumbar plexus blockade, spinal anaesthesia incorporating adjunctive intrathecal morphine did not result in a statistically significant difference in worst pain on movement/mobilisation during the first 24 hours, although it was associated with better analgesia in the post-anaesthesia care unit. Subsequently, however, these patients appeared to require more rescue morphine and more of them reported pruritus.

Clinical negligence in foot and ankle surgery: A 17-year review of claims to the NHS Litigation Authority.

We present a review of litigation claims relating to foot and ankle surgery in the NHS in England during the 17-year period between 1995 and 2012. A freedom of information request was made to obtain data from the NHS litigation authority (NHSLA) relating to orthopaedic claims, and the foot and ankle claims were reviewed. During this period of time, a total of 10 273 orthopaedic claims were made, of which 1294 (12.6%) were related to the foot and ankle. 1036 were closed, which comprised of 1104 specific complaints. Analysis was performed using the complaints as the denominator. The cost of settling these claims was more than £36 million. There were 372 complaints (33.7%) involving the ankle, of which 273 (73.4%) were related to trauma. Conditions affecting the first ray accounted for 236 (21.4%), of which 232 (98.3%) concerned elective practice. Overall, claims due to diagnostic errors accounted for 210 (19.0%) complaints, 208 (18.8%) from alleged incompetent surgery and 149 (13.5%) from alleged mismanagement. Our findings show that the incorrect, delayed or missed diagnosis of conditions affecting the foot and ankle is a key area for improvement, especially in trauma practice.

Talar neck fracture-a rare but important complication following subtalar arthroereisis.

Subtalar arthroereisis is a technique for treating symptomatic flexible flatfeet by means of inserting an implant or stent into the sinus tarsi. The goals are to reduce pain, deformity and instability of the foot. However, there are recognised complications associated with this technique which include malposition of the implant, undercorrection/overcorrection of the deformity, persistent sinus tarsi pain, deep medial heel pain, foreign body synovitis, avascular necrosis of the talus, intraosseous cystic formation in the talus, migration of the implant, device extrusion and subtalar joint arthrosis. In this report an unusual complication of fracture of the neck of the talus in a teenager who competes recreationally in 'at risk'/impact sports, who had previously had arthroereisis screw insertion some years before is presented.

Oral health and impact on performance of athletes participating in the London 2012 Olympic Games: a cross-sectional study.

BACKGROUND: Oral health is important both for well-being and successful elite sporting performance. Reports from Olympic Games have found significant treatment needs; however, few studies have examined oral health directly. The aim of this study was to evaluate oral health, the determinants of oral health and the effect of oral health on well-being, training and performance of athletes participating in the London 2012 Games. METHODS: Cross-sectional study at the dental clinic within the Polyclinic in the athletes' village. Following informed consent, a standardised history, clinical examination and brief questionnaire were conducted. RESULTS: 302 athletes from 25 sports were recruited with data available for 278. The majority of athletes were from Africa, the Americas and Europe. Overall, the results demonstrated high levels of poor oral health including dental caries (55% athletes), dental erosion (45% athletes) and periodontal disease (gingivitis 76% athletes, periodontitis 15% athletes). More than 40% of athletes were 'bothered' by their oral health with 28% reporting an impact on quality of life and 18% on training and performance. Nearly half of the participants had not undergone a dental examination or hygiene care in the previous year. CONCLUSIONS: The oral health of athletes attending the dental clinic of the London 2012 Games was poor with a resulting substantial negative impact on well-being, training and performance. As oral health is an important element of overall health and well-being, health promotion and disease prevention interventions are urgently required to optimise athletic performance.

Using stable isotopes to follow excreta N dynamics and N2O emissions in animal production systems.

Nitrous oxide (N2O) is a potent greenhouse gas and the dominant anthropogenic stratospheric ozone-depleting emission. The tropospheric concentration of N2O continues to increase, with animal production systems constituting the largest anthropogenic source. Stable isotopes of nitrogen (N) provide tools for constraining emission sources and, following the temporal dynamics of N2O, providing additional insight and unequivocal proof of N2O source, production pathways and consumption. The potential for using stable isotopes of N is underutilised. The intent of this article is to provide an overview of what these tools are and demonstrate where and how these tools could be applied to advance the mitigation of N2O emissions from animal production systems. Nitrogen inputs and outputs are dominated by fertiliser and excreta, respectively, both of which are substrates for N2O production. These substrates can be labelled with 15N to enable the substrate-N to be traced and linked to N2O emissions. Thus, the effects of changes to animal production systems to reduce feed-N wastage by animals and fertiliser wastage, aimed at N2O mitigation and/or improved animal or economic performance, can be traced. Further 15N-tracer studies are required to fully understand the dynamics and N2O fluxes associated with excreta, and the biological contribution to these fluxes. These data are also essential for the new generation of 15N models. Recent technique developments in isotopomer science along with stable isotope probing using multiple isotopes also offer exciting capability for addressing the N2O mitigation quest.

The impact of relict organic materials on the denitrification capacity in the unsaturated-saturated zone continuum of three volcanic profiles.

The denitrification capacity of wetlands, riparian zones, and aquifers in glacial outwash areas is well documented, but little or no information exists for volcanic profiles, particularly those containing relict organic matter contained in or on top of paleosols (old soils buried by volcanic deposits) below the groundwater table. Relict carbon contained in these layers could provide the necessary electrons to fuel heterotrophic denitrification. To the best of our knowledge, this is the first study investigating the denitrification capacity in both the unsaturated and saturated zone of volcanic profiles. Samples from three profile types with differing organic matter distribution were amended with N-enriched nitrate (NO-) and incubated in the laboratory under anaerobic conditions. Dinitrogen (N) dominated the N gas fluxes; averaged across all samples, it accounted for 96% of the total N (nitrous oxide [NO] and N) gas fluxes. Dinitrogen fluxes were generally highest in the A horizon samples (4.1-6.2 nmol N g h), but substantial fluxes were also observed in some paleosol layers (up to 0.72 nmol N g h). A significant correlation ( < 0.001) was found between the concentration of extractable dissolved organic carbon and the total N gas flux produced in samples from below the A horizon, suggesting that heterotrophic denitrification was the dominant NO attenuation process in this study. Extrapolation of lab-derived denitrification capacities to field conditions suggests that the denitrification capacity of profiles containing relict soil organic matter in the saturated zone exceeds the estimated N leaching from the root zone.

Ultrasound-guided femoral catheter placement: a randomised comparison of the in-plane and out-of-plane techniques.

In-plane vs out-of-plane needle-probe alignment for perineural catheter placement remains controversial. Patients presenting for major knee surgery were randomly assigned to out-of-plane (n = 42) or in-plane (n = 39) needle-probe alignment for femoral nerve catheter placement, with both techniques using short-axis nerve imaging. Twenty millilitres of ropivacaine 0.5% was administered via the catheter followed by a ropivacaine elastomeric infusion incorporating on-demand boluses. All patients received pre-operative single-injection sciatic and obturator blocks and general anaesthesia. The primary outcome, numerically rated worst pain on movement (0-10) during the first 24 h, demonstrated equivalence within two points of the scale at a 5% significance level using two one-sided tests (corresponding 90% CI -1.2 to 0.6). There were no differences between groups for all secondary outcomes, including numerically rated worst rest pain, ropivacaine bolus and tramadol consumption. These results suggest that for ultrasound-guided femoral catheter placement using short-axis nerve imaging, operators should use the needle-probe alignment technique with which they are most familiar.

Nitrous oxide dynamics in a braided river system, New Zealand.

Recently the Intergovernmental Panel on Climate Change (IPCC) emission factor EF5-r was revised downward to a value of 0.0025 kg N2O-N per kg NO3-N leached. It was not reduced further due to the continued uncertainty surrounding the dynamics of N2O in river systems. There have been few studies where river system N2O yields and fluxes have been measured. In this study, we examined the relationship between NO3-N and N2O-N fluxes at 10 sites along a braided river system (84 km) over a 397-d period. Isotopic analysis of NO3-N river water samples and the potential agricultural nitrogen (N) sources demonstrated that the NO3-N came from agricultural or sewage sources. Percent saturation of N2O varied with site and date (average, 114%) and correlated with river N2O-N concentrations. Modeled N2O fluxes (16-30 µg m(-2) h(-1)) from five sites were strongly related to river NO3-N concentrations ( r² = 0.86). The modeled N2O-N fluxes ranged from 39 to 81% of the IPCC-derived emissions based on the NO3-N load in the river over 397 d and do not support further lowering of the EF5-r. Further in situ river studies are required to verify the N2O-N fluxes and the calculated gas transfer velocity values for these braided river systems.

Ambulatory continuous femoral analgesia for major knee surgery: a randomised study of ultrasound-guided femoral catheter placement.

Needle-nerve stimulation has a false negative motor response rate, which may increase needle passes. This prospective, randomised study tested the hypothesis that femoral nerve catheters placed with ultrasound-only guidance could provide comparable postoperative analgesia to those placed using a conventional nerve stimulation endpoint. Patients presenting for major knee surgery to the lead investigator were recruited. Needles introduced for femoral nerve catheter placement were initially guided with 'oblique' out-of-plane ultrasound imaging but were then prospectively randomised to either an ultrasound (n = 21) or nerve stimulation (n = 24) endpoint. An elastomeric infusion of ropivacaine 0.2% 2 ml/hour with as required hourly 5 ml boluses was continued for > 48 hours in hospital and/or in the home. Needle time under the skin and numerical rating pain score during insertion were recorded. Patients were questioned for worst numerical rating pain score, the need for supplementary ropivacaine boluses and tramadol on postoperative days one and two. There was no difference in the worst numerical rating pain score at rest and on movement and the requirement for supplementary ropivacaine boluses or tramadol during the first 48 postoperative hours. The median (quartiles) needle time under the skin was 58 seconds (51 to 76) in the ultrasound group and 120 seconds (95 to 178) in the nerve stimulation group (P = 0.001). The median (quartiles) insertion numerical rating pain score was 2 (0 to 2) in the ultrasound group and 4 (2 to 6) in the nerve stimulation group (P = 0.014). Femoral nerve catheters placed for major knee surgery using an ultrasound endpoint provided postoperative analgesia comparable to that obtained when using a nerve stimulation endpoint and were associated with a reduction in both needle manipulations and procedure-related pain.

Methods to adjust for the interference of N2O on delta13C and delta18O measurements of CO2 from soil mineralization.

In this paper we present an overview of the present knowledge relating to methods that avoid interference of N2O on delta13C and delta18O measurements of CO2. The main focus of research to date has been on atmospheric samples. However, N2O is predominantly generated by soil processes. Isotope analyses related to soil trace gas emissions are often performed with continuous flow isotope ratio mass spectrometers, which do not necessarily have the high precision needed for atmospheric research. However, it was shown by using laboratory and field samples that a correction to obtain reliable delta13C and delta18O values is also required for a commercial continuous flow isotope ratio mass spectrometer. The capillary gas chromatography column of the original equipment was changed to a packed Porapak Q column. This adaptation resulted in an improved accuracy and precision of delta13C (standard deviation(Ghent): from 0.2 to 0.08 per thousand; standard deviation(Lincoln): from 0.2 to 0.13 per thousand) of CO2 for N2O/CO2 ratios up to 0.1. For delta18O there was an improvement for the standard deviation measured at Ghent University (0.13 to 0.08 per thousand) but not for the measurements at Lincoln University (0.08 to 0.23 per thousand). The benefits of using the packed Porapak Q column compared with the theoretical correction method meant that samples were not limited to small N(2)O concentrations, they did not require an extra N2O concentration measurement, and measurements were independent of the variable isotopic composition of N2O from soil.

Severe necrotising soft tissue infections in orthopaedic surgery.

PURPOSE: To review all cases of necrotising infection managed in the Department of Orthopaedic Surgery of Dunedin Hospital in New Zealand between 1989 and 1998. METHODS: Hospital records were analysed for predisposing factors, clinical features, diagnostic results, treatment strategies, and outcomes. RESULTS: 13 cases (9 males and 4 females) of necrotising infection were identified. The mean age was 48 years (range, 8-76 years). Presenting symptoms included painful swelling, erythema, and necrosis. Most patients had predisposing factors and had received nonsteroidal anti-inflammatory drugs before presentation. 12 patients underwent surgical debridement including a total of 4 amputations. Septic shock developed in 9 patients who required dialysis for renal failure. Four patients died. The most common organisms identified were group A beta-haemolytic streptococci. CONCLUSION: Severe necrotising infections require a high index of suspicion and rapid medical and surgical intervention to reduce the mortality and morbidity.