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To present a clear and comprehensive summary of the published data on unicompartmental knee replacement (UKA) or total knee replacement (TKA), comparing domains of outcome that have been shown to be important to patients and clinicians to allow informed decision making. Systematic review using data from randomised controlled trials, nationwide databases or joint registries, and large cohort studies. Medline, Embase, Cochrane Controlled Register of Trials (CENTRAL), and Clinical Trials.gov, searched between 1 January 1997 and 31 December 2018. Studies published in the past 20 years, comparing outcomes of primary UKA with TKA in adult patients. Studies were excluded if they involved fewer than 50 participants, or if translation into English was not available. 60 eligible studies were separated into three methodological groups: seven publications from six randomised controlled trials, 17 national joint registries and national database studies, and 36 cohort studies. Results for each domain of outcome varied depending on the level of data, and findings were not always significant. Analysis of the three groups of studies showed significantly shorter hospital stays after UKA than after TKA (-1.20 days (95% confidence interval -1.67 to -0.73), -1.43 (-1.53 to -1.33), and -1.73 (-2.30 to -1.16), respectively). There was no significant difference in pain, based on patient reported outcome measures (PROMs), but significantly better functional PROM scores for UKA than for TKA in both non-trial groups (mean difference -0.58 (-0.88 to -0.27) and -0.32 (-0.48 to -0.15), respectively). Regarding major complications, trials and cohort studies had non-significant results, but mortality after TKA was significantly higher in registry and large database studies (risk ratio 0.27 (0.16 to 0.45)), as were venous thromboembolic events (0.39 (0.27 to 0.57)) and major cardiac events (0.22 (0.06 to 0.86)). Early reoperation for any reason was higher after TKA than after UKA, but revision rates at five years remained higher for UKA in all three study groups (risk ratio 5.95 (1.29 to 27.59), 2.50 (1.77 to 3.54), and 3.13 (1.89 to 5.17), respectively). TKA and UKA are both viable options for the treatment of isolated unicompartmental osteoarthritis. By directly comparing the two treatments, this study demonstrates better results for UKA in several outcome domains. However, the risk of revision surgery was lower for TKA. This information should be available to patients as part of the shared decision making process in choosing treatment options. PROSPERO number CRD42018089972.

Background:Although knee osteoarthritis (OA) is the most prevalent chronic musculoskeletal debilitating disease, there is no recognized marker to stratify OA patients. The infrapatellar fat pad (IPFP), although not yet as widely studied as other knee tissues, has been recognized as a likely key player in OA. However, there is sparse and conflicting data about which of this tissue’s morphology is the best forecasting marker of the disease’s symptoms, joint structural changes, and patient outcomes.Objectives:We hypothesized that some knee IFPP morphological features at baseline could be used as a prognostic marker of the OA disease symptoms, progression, and knee replacement. We also explored whether IPFP morphology changes are associated with disease symptoms and joint structure changes over time.Methods:By using a longitudinal study (0-96 months), the target knees (n=1075) of participants from the Osteoarthritis Initiative (OAI) progressor cohort were analyzed for their structural changes using X-ray for joint space width (JSW) and quantitative and automated MRI for cartilage, bone marrow lesions (BML) and effusion volumes, as well as the IPFP morphology (total volume and maximal area, and hyperintensity signal volume and area). The symptoms were evaluated using WOMAC and KOOS scores. The knee replacement was as in the OAI database. The analyses were performed at baseline and 12, 24, 48, and 96 months post-inclusion. Changes over time were calculated as the value at the follow-up minus the one at study inclusion, divided by the value at study inclusion. Overtime evolution was analyzed using the mixed model for repeated measures (MMRM) and association by ANCOVA.Results:At baseline, a significant association was found between the IPFP total volume and maximal area, as well as hyperintensity signal volume and area with the cartilage (p≤0.001), effusion (p≤0.001; except IPFP area) and BML (p≤0.027; except hyperintensity signal) volumes. Over time (0-96 months), there was a decrease in disease symptoms (WOMAC, KOOS; p≤0.001), IPFP total volume and maximal area (p≤0.001), JSW (p<0.001), cartilage volume (p<0.001), and an increase in effusion (p<0.001) and hyperintensity signal volume and area (p≤0.001). Importantly, significant associations were found between baseline hyperintensity signal volume with changes in JSW (96 months; p=0.008), cartilage (48 months; p=0.026) and effusion (96 months; p=0.038) volumes, as well as between the hyperintensity area with BML volume (12 months; p=0.044). Regarding the association for the changes of both IPFP morphology and knee structures, the most significant were the changes in the IPFP total volume with JSW (48 months; p<0.001), cartilage (24, 48 months; p≤0.049) and BML (24 months; p<0.02) volumes, and a trend toward significant difference at 12 and 48 months for BML and at 48 months for effusion volumes (p≤0.062). As for the disease symptoms or knee replacement, there was no association either at baseline or with the changes in the studied IPFP morphology.Conclusion:This extensive framework forecasting the progression of knee OA structural alterations revealed that the IPFP hyperintensity signal volume could be used as an early prognostic marker and that changes over time in the IPFP total volume were well associated with changes in the knee structural progression. This study offers a new approach for stratifying OA structural progressors.REFERENCES:NIL.Acknowledgements:The authors would like to thank the Osteoarthritis Initiative (OAI) participants and the Coordinating Center. The OAI is a public-private partnership funded by the National Institutes of Health. A special thanks to ArthroLab Inc. for providing the MRI data for this study.Disclosure of Interests:None declared.

A global, monthly averaged time series of Sun-induced Fluorescence (SiF), spanning January 2007 to June 2015, was derived from Metop-A Global Ozone Monitoring Experiment 2 (GOME-2) spectral measurements. Far-red SiF was retrieved using the filling-in of deep solar Fraunhofer lines and atmospheric absorption bands based on the general methodology described by Joiner et al, AMT, 2013. A Principal Component (PC) analysis of spectra over non-vegetated areas was performed to describe the effects of atmospheric absorption. Our implementation (SiF KNMI) is an independent algorithm and differs from the latest implementation of Joiner et al, AMT, 2013 (SiF NASA, v26), because we used desert reference areas for determining PCs (as opposed to cloudy ocean and some desert) and a wider fit window that covers water vapour and oxygen absorption bands (as opposed to only Fraunhofer lines). As a consequence, more PCs were needed (35 as opposed to 12). The two time series (SiF KNMI and SiF NASA, v26) correlate well (overall R of 0.78) except for tropical rain forests. Sensitivity experiments suggest the strong impact of the water vapour absorption band on retrieved SiF values. Furthermore, we evaluated the SiF time series with Gross Primary Productivity (GPP) derived from twelve flux towers in Australia. Correlations for individual towers range from 0.37 to 0.84. They are particularly high for managed biome types. In the de-seasonalized Australian SiF time series, the break of the Millennium Drought during local summer of 2010/2011 is clearly observed.

Abstract Objectives To determine the feasibility of a randomized controlled trial (RCT) examining outdoor walking on knee osteoarthritis (KOA) clinical outcomes and magnetic resonance imaging (MRI) structural changes.MethodThis was a 24-week parallel two-arm pilot RCT in Tasmania, Australia. KOA participants were randomized to either a walking plus usual care group or a usual care control group. The walking group trained 3 days/week. The primary outcome was feasibility assessed by changes being required to the study design, recruitment, randomization, program adherence, safety, and retention. Exploratory outcomes were changes in symptoms, physical performance/activity, and MRI measures.ResultsForty participants (mean age 66 years (SD 1.4) and 60% female) were randomized to walking (n = 24) or usual care (n = 16). Simple randomization resulted in a difference in numbers randomized to the two groups. During the study, class sizes were reduced from 10 to 8 participants to improve supervision, and exclusion criteria were added to facilitate program adherence. In the walking group, total program adherence was 70.0% and retention 70.8% at 24 weeks. The walking group had a higher number of mild adverse events and experienced clinically important improvements in symptoms (e.g., visual analogue scale (VAS) knee pain change in the walking group: − 38.7 mm [95% CI − 47.1 to − 30.3] versus usual care group: 4.3 mm [− 4.9 to 13.4]).ConclusionsThis study supports the feasibility of a full-scale RCT given acceptable adherence, retention, randomization, and safety, and recruitment challenges have been identified. Large symptomatic benefits support the clinical usefulness of a subsequent trial.Trial registration number12618001097235.Key Points• This pilot study is the first to investigate the effects of an outdoor walking program on knee osteoarthritis clinical outcomes and MRI joint structure, and it indicates that a full-scale RCT is feasible.• The outdoor walking program (plus usual care) resulted in large improvements in self-reported knee osteoarthritis symptoms compared to usual care alone.• The study identified recruitment challenges, and the manuscript explores these in more details and provides recommendations for future studies.

Solar-induced fluorescence (SIF) data from satellites are increasingly used as a proxy for photosynthetic activity by vegetation, and as a constraint on gross primary production. Here we report on improvements in the algorithm to retrieve mid-morning (09:30 hrs local time) SIF estimates on the global scale from GOME-2 sensor on the Metop-A satellite (GOME-2A) for the period 2007-2019. Our new SIFTER (Sun-Induced Fluorescence of Terrestrial Ecosystems Retrieval) v2 algorithm improves over a previous version by using a narrower spectral window that avoids strong oxygen absorption and is less sensitive to water vapour absorption, by constructing stable reference spectra from a 6-year period (2007-2012) of atmospheric spectra over the Sahara, and by applying a latitude-dependent zero-level adjustment that accounts for biases in the data product. We generated stable, good-quality SIF retrievals between January 2007 and June 2013, when GOME-2A degradation in the near infrared was still limited. After the narrowing of the GOME-2A swath in July 2013, we characterized the throughput degradation of the level-1 data in order to derive reflectance corrections and apply these for the SIF retrievals between July 2013 and December 2018. SIFTER v2 data compares well with the independent NASA v2.8 data product. Especially in the evergreen tropics, SIFTER v2 no longer shows the underestimates against other satellite products that were seen in SIFTER v1. The new data product includes uncertainty estimates for individual observations, and is best used for mostly clear-sky scenes, and when spectral residuals remain below a certain spectral autocorrelation threshold. Our results support the use of SIFTER v2 data to be used as an independent constraint on photosynthetic activity on regional to global scales.

ObjectivesTo identify: (1) patient-reported outcome measures (PROMs) used to evaluate symptoms, health status or quality of life following discretionary revision (or re-revision) knee joint replacement, and (2) validated joint-specific PROMs, their measurement properties and quality of evidence.Design(1) Scoping review; (2) systematic review following the COnsensus-based Standards for selection of health status Measurement INstruments (COSMIN) checklist.Data sourcesMEDLINE, Embase, AMED and PsycINFO were searched from inception to 1 July 2020 using the Oxford PROM filter unlimited by publication date or language.Eligibility criteria for selecting studiesStudies reporting on the development, validation or outcome of a joint-specific PROM for revision knee joint replacement were included.Results51 studies reported PROM outcomes using eight joint-specific PROMs. 27 out of 51 studies (52.9%) were published within the last 5 years. PROM development was rated ‘inadequate’ for each of the eight PROMs studied. Validation studies were available for only three joint-specific PROMs: Knee Injury and Osteoarthritis Outcome Score (KOOS), Lower Extremity Activity Scale (LEAS) and Western Ontario and McMaster Universities Arthritis Index (WOMAC). 25 out of 27 (92.6%) measurement properties were rated insufficient, indeterminate or not assessed. The quality of supporting evidence was mostly low or very low. Each of the validated PROMs was rated ‘B’ (potential for recommendation but require further evaluation).ConclusionJoint-specific PROMs are increasingly used to report outcomes following revision knee joint replacement, but these instruments have insufficient evidence for their validity. Future research should be directed toward understanding the measurement properties of these instruments in order to inform clinical trials and observational studies evaluating the outcomes from joint-specific PROMs.

Objective To identify predictive factors for total knee replacement (TKR) using data from MRI of knee osteoarthritis patients in a phase III multicentre disease-modifying osteoarthritis drug (DMOAD) study. Methods Knee osteoarthritis patients from a 2-year clinical trial evaluating licofelone versus naproxen were investigated for the incidence of TKR of the study knee. Patients (n=161) who completed the study according to protocol were selected. Incidence of TKR was assessed blindly to the treatment following telephone interviews (n=123). Results 18 TKR (14.6%) were performed in 4–7 years following enrolment in the original study. More TKR were performed within the naproxen than the licofelone group (61% vs 39%, p=0.232). Baseline score of bone marrow lesions (BML) in the medial compartment (p=0.0001), medial joint space width (JSW) as assessed by standardised radiographs (p=0.0008), presence of severe medial meniscal tear (p=0.004), medial meniscal extrusion (p=0.013), and C-reactive protein level (p=0.049) were strong predictors of TKR. Changes at the end of the study also yielded strong predictors: change in cartilage volume of the medial compartment (p=0.005) and of the global knee (p=0.034), reduction in the JSW of greater than 7% (p=0.009), and WOMAC pain (p=0.009) and function (p=0.023) scores. Multivariate analysis showed that baseline severe medial meniscal tear (p=0.023) and presence of medial BML (p=0.025) were the strongest independent long-term predictors of TKR. Conclusion This study shows that in the context of osteoarthritis trials, clinical data and structural changes identified by MRI allow prediction of a ‘hard’ outcome such as TKR. The findings support the usefulness and predictive value of MRI in defining study outcome in DMOAD trials.

ObjectiveMeniscal tears occur frequently in the population and the most common surgical treatment, arthroscopic partial meniscectomy, is performed in approximately two million cases worldwide each year. The purpose of this systematic review is to summarise and critically appraise the evidence for the use of patient-reported outcome measures (PROMs) in patients with meniscal tears.DesignA systematic review was undertaken. Data on reported measurement properties were extracted and the quality of the studies appraised according to Consensus-based Standards for the Selection of Health Measurement Instruments.Data sourcesA search of MEDLINE, Embase, AMED and PsycINFO, unlimited by language or publication date (last search 20 February 2017).Eligibility criteria for selecting studiesDevelopment and validation studies reporting the measurement properties of PROMs in patients with meniscal tears were included.Results11 studies and 10 PROMs were included. The overall quality of studies was poor. For measurement of symptoms and functional status, there is only very limited evidence supporting the selection of either the Lysholm Knee Scale, International Knee Documentation Committee Subjective Knee Form or the Dutch version of the Knee injury and Osteoarthritis Outcome Score. For measuring health-related quality of life, only limited evidence supports the selection of the Western Ontario Meniscal Evaluation Tool (WOMET). Of all the PROMs evaluated, WOMET has the strongest evidence for content validity.ConclusionFor patients with meniscal tears, there is poor quality and incomplete evidence regarding the validity of the currently available PROMs. Further research is required to ensure these PROMs truly reflect the symptoms, function and quality of life of patients with meniscal tears.PROSPERO registration numberCRD42017056847.

Objective:In a multicentre study to explore the effects of licofelone as a disease-modifying osteoarthritis drug in comparison with naproxen in patients with knee osteoarthritis (OA), using MRI and x-ray examination.Methods:Patients with knee OA (n = 355) were randomised to receive either licofelone (200 mg twice a day) or naproxen (500 mg twice a day). MRI and x-ray examinations were performed at baseline, 6 months (MRI only), 12 and 24 months. MRI was used to assess quantitatively changes in cartilage volume, and x-ray examinations (Lyon–Schuss) to measure changes in the mean and minimum joint space width (JSW) in the medial compartment. Questionnaires probing symptoms were completed. Data were presented as intention to treat (ITT) and according to protocol (ATP).Results:Cartilage volume loss in the global joint and medial and lateral compartments was significantly less in the licofelone than in the naproxen group for ITT at 12 and 24 months and for ATP at all times except in the medial compartment. Patients with medial meniscal extrusion had a greater loss of cartilage volume. In these patients, licofelone markedly reduced the cartilage loss for both ITT and ATP at 12 and 24 months. Although licofelone showed less reduction in the JSW than naproxen, this did not reach significance. All clinical variables were improved at 24 months (p<0.001) for both groups, with a good safety profile.Conclusion:Licofelone and naproxen were equally effective in reducing OA symptoms; however, licofelone significantly reduced cartilage volume loss over time, thus having a protective effect in patients with knee OA. This study proves the superiority of quantitative MRI over x-ray examinations in a multicentre clinical trial.