No difference in risk of revision due to infection between clindamycin and cephalosporins as antibiotic prophylaxis in cemented primary total knee replacements: a report from the Norwegian Arthroplasty Register 2005–2020

Background and purpose: Systemic antibiotic prophylaxis with clindamycin, which is often used in penicillin- or cephalosporin-allergic patients’, has been associated with a higher risk of surgical revision for deep prosthetic joint infection (PJI) than cloxacillin in primary total knee replacement (TKR). We aimed to investigate whether clindamycin increases the risk of surgical revisions due to PJI compared with cephalosporins in primary cemented TKR. Patients and methods: Data from 59,081 TKRs in the Norwegian Arthroplasty Register (NAR) 2005–2020 was included. 2,655 (5%) received clindamycin and 56,426 (95%) received cephalosporins. Cox regression analyses were performed with adjustment for sex, age groups, diagnosis, and ASA score. Survival times were calculated using Kaplan–Meier estimates and compared using Cox regression with revision for PJI as endpoint. The cephalosporins cefalotin and cefazolin were also compared. Results: Of the TKRs included, 1.3% (n = 743) were revised for PJI. 96% (n = 713) had received cephalosporins and 4% (n = 30) clindamycin for perioperative prophylaxis. Comparing cephalosporins (reference) and clindamycin, at 3-month follow-up the adjusted hazard ratio rate (HRR) for PJI was 0.7 (95% confidence interval [CI] 0.4–1.4), at 1 year 0.9 (CI 0.6–1.5), and at 5 years 0.9 (CI 0.6–1.4). Analysis using propensity score matching showed similar results. Furthermore, comparing cefalotin (reference) and cefazolin, HRR was 1.0 (CI 0.8–1.4) at 3 months and 1.0 (CI 0.7–1.3) at 1-year follow-up. Conclusion: We found no difference in risk of revision for PJI when using clindamycin compared with cephalosporins in primary cemented TKRs. It appears safe to continue the use of clindamycin in penicillin- or cephalosporin-allergic patients.publishedVersio

Antibiotic-loaded bone cement in prevention of periprosthetic joint infections in primary total knee arthroplasty: A register-based multicentre randomised controlled non-inferiority trial (ALBA trial)

Introduction The current evidence on the efficacy of antibiotic-loaded bone cement (ALBC) in reducing the risk of periprosthetic joint infections (PJI) after primary joint reconstruction is insufficient. In several European countries, the use of ALBC is routine practice unlike in the USA where ALBC use is not approved in low-risk patients. Therefore, we designed a double-blinded pragmatic multicentre register-based randomised controlled non-inferiority trial to investigate the effects of ALBC compared with plain bone cement in primary total knee arthroplasty (TKA). Methods and analysis A minimum of 9,172 patients undergoing full-cemented primary TKA will be recruited and equally randomised into the ALBC group and the plain bone cement group. This trial will be conducted in Norwegian hospitals that routinely perform cemented primary TKA. The primary outcome will be risk of revision surgery due to PJI at 1-year of follow-up. Secondary outcomes will be: risk of revision due to any reason including aseptic loosening at 1, 6, 10 and 20 years of follow-up; patient-related outcome measures like function, pain, satisfaction and health-related quality of life at 1, 6 and 10 years of follow-up; risk of changes in the microbial pattern and resistance profiles of organisms cultured in subsequent revisions at 1, 6, 10 and 20 years of follow-up; cost-effectiveness of routine ALBC versus plain bone cement use in primary TKA. We will use 1:1 randomisation with random permuted blocks and stratify by participating hospitals to randomise patients to receive ALBC or plain bone cement. Inclusion, randomisation and follow-up will be through the Norwegian Arthroplasty Register. Ethics and dissemination The trial was approved by the Western Norway Regional Committees on Medical and Health Research Ethics (reference number: 2019/751/REK vest) on 21 June 2019. The findings of this trial will be disseminated through peer-reviewed publications and conference presentations. Trial registration number NCT04135170.publishedVersio

Revision Knee Arthroplasty in Norway 1994-2011. A register-based study with focus on implant survival, causes and risk of re-revision, pain relief, functional outcome, patient satisfaction, and health related quality of life

Background and purpose: Globally, the number of both primary and revision knee arthroplasty surgeries performed each year is increasing. Revision knee arthroplasty surgery is more expensive, technically more difficult and complicated, and consumes more time and supplies than the primary knee arthroplasty surgery. Consequently, a reduced number of revisions would mean significant cost saving for society as well as reduced risk of pain, loss of function, and risk of complications for the patients. The overall aim of this thesis was to evaluate the outcomes of aseptic revision knee arthroplasties in Norway in terms of implant survival rate, causes and risk of rerevision, pain relief, functional outcome, patient satisfaction, and health related quality of life (HRQOL). Materials and Methods: All studies included in this thesis were based on aseptic revision knee arthroplasties reported to the Norwegian Arthroplasty Register (NAR) in the period 1994-2011 (Paper I-III) and additional information on patient reported outcomes (PROs) data in the period 1994-2005 (Paper II and III). The PROs data were on HRQOL (using EQ-5D), functional outcome, pain, and knee related quality of life (using the Knee Injury and Osteoarthritis Outcome Score (KOOS)), postoperative pain and satisfaction (using Visual Analogue Scale (VAS)), and on musculoskeletal comorbidity (using Charnley Category A, B, C). Kaplan-Meier and Coxregression were used to analyze prostheses survival rate and the risk of re-revision, whereas t-test and multiple linear regression were used to evaluate mean differences in the patient reported outcome measures (PROMs) scores between different revision procedures or treatment groups. Results: Paper I was based on 1016 primary Total Knee Arthroplasties (TKAs) revised to TKAs (rev-TKAs). The 10 years survival percentage was 78 %. Deep infection (28 %) and instability (26 %) were found to be the two most frequent causes of rerevision. Rev-TKAs with an exchange of the femoral or tibial component exclusively had a higher risk of re-revision (Relative Risk (RR) =1.7; p=0.02) compared to those with an exchange of the whole prosthesis. The risk of re-revision was double for men as compared to women (RR=2.0; p70 years (RR=1.6; p=0.03). The use of bone impaction grafting had a positive effect on the survival rate whereas the use of long stem extensions, stabilization, bone cement, and patella resurfacing had no significant effect on the risk of re-revision. Survival rates were similar among prosthesis brands. In Paper II, the survival rate of TKAs revised with isolated secondary patella resurfacing (SPR) was assessed based on 308 knees (301 patients) of which 114 patient had PRO data. The 10 years survival of these revisions was 87 %. Pain alone (10 knees) was the most frequent cause of re-revision. The risk of re-revision was nearly 9 times higher for patients aged 70 years (RR=8.6; p70 years) had better mean scores in the KOOS subscales compared to younger patients (≤ 70 years). Patients with unilateral knee joint problem (Charnley category ‘A’) had significantly better mean score in the KOOS subscales than patients with bilateral or multiple joint or general health problems. In Paper III, the survival rates of Unicompartmental Knee Arthroplasties (UKAs) to TKA (rev-UKAs) vs rev-TKA were assessed based on 768 rev-TKAs and 578 rev- UKAs, and clinical outcome was assessed based on PROs data from 150 of the 768 rev-TKAs and 127 of the 578 rev-UKAs. The technical difficulty of the surgical procedure for these two revision groups were assessed as a proxies of the length of operative time, and the need for bone impaction grafting, stem extensions, and/ or stabilization. The 10 years survival percentage of rev-UKAs vs rev-TKAs was 82 vs 81 %, respectively. The overall risk of a re-revision for rev-UKAs vs rev-TKAs was similar (RR= 1.3; p=0.2), nor did we find any differences in the mean PROM scores. For the elderly (> 70 years), however, the risk of a re-revision was double for rev-TKAs compared to the rev-UKAs (RR= 2.1; p=0.05). Loose tibia (28 vs 17 %), pain alone (21 vs 12 %), instability (19 vs 19 %), and deep infection (16 vs 31 %) were main causes of re-revision for rev-UKAs vs rev-TKAs, respectively. The observed differences in the proportion of reasons for re-revision were statistically significant only for the deep infection where the rev-TKAs were 2.2 times more frequently re-revised due to deep infection than the rev-UKAs (RR=2.2; p=0.03). The surgical procedure for rev-TKAs took longer time (mean=150 vs 114 minutes) and needed more stems (58 vs 19 %), bone impaction (24 vs 19 %), and stabilizing (27 vs 9 %) compared to rev-UKAs. Conclusions: The overall conclusion of this PhD study is that the long-term implant survival following aseptic revision knee arthroplasty in Norway in the period between 1994 and 2011 was satisfactory (range 78-87 % at 10 years), and a number of points were noted. Specifically: i) Complete TKA revisions had better implant survival rate than partial revisions. Thus, partial revisions should only be done after careful consideration in specific instances. Male gender and younger age (<60 years) were risk factors for rerevision. Patellar resurfacing, prosthesis brands, constrained implants, the use of stem extensions, and/or fixation method had no effect on the survival of rev-TKAs, whereas cases with bone impaction grafting had better results in terms of survival. Deep infection and instability were the most frequent causes of failure of rev-TKAs (Paper I). ii) For isolated SPR procedures pain and loosening were the main causes for re-revision. Young age (<60 years) was a risk factor for re-revision after these procedures. The mean HRQOL significantly improved following SPR. Isolated SPR procedure can provide a solution to patients with severe preoperative pain. Still, more than one-third of patients were dissatisfied with the outcomes of the SPR procedure. Male patients had a better post-revision improvement in mean EQ-5D index score, and patients with a unilateral joint problem (Charnley category ‘A’) had significantly better mean score in KOOS subscales than the other categories following revision TKA with isolated SPR (Paper II). iii) The overall outcomes of rev-UKAs and rev-TKAs in terms of implant survival rates, functional outcome, level of postoperative pain, patient satisfaction, and change on HRQOL status were similar. However, rev-TKAs seemed to be a technically more difficult surgical procedure, were re-revised more frequently due to deep infection, and had a double risk of re-revision for patient older than 70 years compared to that of rev-UKAs (Paper III)

Performance Evaluation and Comparison of Satellite-Derived Rainfall Datasets over the Ziway Lake Basin, Ethiopia

Consistent time series rainfall datasets are important in performing climate trend analyses and agro-hydrological modeling. However, temporally consistent ground-based and long-term observed rainfall data are usually lacking for such analyses, especially in mountainous and developing countries. In the absence of such data, satellite-derived rainfall products, such as the Climate Hazard Infrared Precipitations with Stations (CHIRPS) and Global Precipitation Measurement Integrated Multi-SatellitE Retrieval (GPM-IMERG) can be used. However, as their performance varies from region to region, it is of interest to evaluate the accuracy of satellite-derived rainfall products at the basin scale using ground-based observations. In this study, we evaluated and demonstrated the performance of the three-run GPM-IMERG (early, late, and final) and CHIRPS rainfall datasets against the ground-based observations over the Ziway Lake Basin in Ethiopia. We performed the analysis at monthly and seasonal time scales from 2000 to 2014, using multiple statistical evaluation criteria and graphical methods. While both GPM-IMERG and CHIRPS showed good agreement with ground-observed rainfall data at monthly and seasonal time scales, the CHIRPS products slightly outperformed the GPM-IMERG products. The study thus concluded that CHIRPS or GPM-IMERG rainfall data can be used as a surrogate in the absence of ground-based observed rainfall data for monthly or seasonal agro-hydrological studies

Failure of aseptic revision total knee arthroplasties: 145 Revision failures from the Norwegian Arthroplasty Register, 1994-2011

Background and purpose — In Norway, the proportion of revision knee arthroplasties increased from 6.9% in 1994 to 8.5% in 2011. However, there is limited information on the epidemiology and causes of subsequent failure of revision knee arthroplasty. We therefore studied survival rate and determined the modes of failure of aseptic revision total knee arthroplasties. Method — This study was based on 1,016 aseptic revision total knee arthroplasties reported to the Norwegian Arthroplasty Register between 1994 and 2011. Revisions done for infections were not included. Kaplan-Meier and Cox regression analyses were used to assess the survival rate and the relative risk of re-revision with all causes of re-revision as endpoint. Results — 145 knees failed after revision total knee arthroplasty. Deep infection was the most frequent cause of re-revision (28%), followed by instability (26%), loose tibial component (17%), and pain (10%). The cumulative survival rate for revision total knee arthroplasties was 85% at 5 years, 78% at 10 years, and 71% at 15 years. Revision total knee arthroplasties with exchange of the femoral or tibial component exclusively had a higher risk of re-revision (RR = 1.7) than those with exchange of the whole prosthesis. The risk of re-revision was higher for men (RR = 2.0) and for patients aged less than 60 years (RR = 1.6). Interpretation — In terms of implant survival, revision of the whole implant was better than revision of 1 component only. Young age and male sex were risk factors for re-revision. Deep infection was the most frequent cause of failure of revision of aseptic total knee arthroplasties

Spatiotemporal Trend Analysis of Temperature and Rainfall over Ziway Lake Basin, Ethiopia

Rainfall and temperature trends detection is vital for water resources management and decision support systems in agro-hydrology. This study assessed the historical (1983–2005) and future (2026–2100) rainfall, maximum temperature (Tmax), and minimum temperature (Tmin) trends of the Ziway Lake Basin (Ethiopia). The daily observed rainfall and temperature data at eleven stations were obtained from the National Meteorological Agency (NMA) of Ethiopia, while simulated historical and future climate data were obtained from the Coupled Model Intercomparison Project 5 (CMIP5) datasets under Representative Concentration Pathways (RCP) of 4.5 and 8.5. The CMIP5 datasets were statistically downscaled by using the climate model data for hydrologic modeling (CMhyd) tool and bias corrected using the distribution mapping method available in the CMhyd tool. The performance of simulated rainfall, Tmax, and Tmin of the CMIP5 models were statistically evaluated using observation datasets at eleven stations. The results showed that the selected CMIP5 models can reasonably simulate the monthly rainfall, Tmax, and Tmin at the majority of the stations. Modified Mann–Kendall trend test were applied to estimate the trends of annual rainfall, Tmax, and Tmin in the historical and future periods. We found that rainfall experienced no clear trends, while Tmax, and Tmin showed consistently significant increasing trends under both RCP 4.5 and 8.5 scenarios. However, the warming is expected to be greater under RCP 8.5 than RCP 4.5 by the end of the 21st century, resulting in an increasing trend of Tmax and Tmin at all stations. The greatest warming occurred in the central part of the basin, with statistically significant increases largely seen by the end of the 21st century, which is expected to exacerbate the evapotranspiration demand of the area that could negatively affect the freshwater availability within the basin. This study increases our understanding of historic trends and projected future change effects on rainfall- and evapotranspiration-related climate variables, which can be used to inform adaptive water resource management strategies

Response of Winter Wheat Production to Climate Change in Ziway Lake Basin

The crop production and limited freshwater resources in the Central Rift Valley (CRV) Lake Basin of Ethiopia have been facing pressure from warmer and drier climates. Thus, irrigation with the goal of increasing water use efficiency and the productivity of rainfed agriculture is vital to address climate effects, water scarcity, and food security. This study is aimed at assessing the sustainability of winter wheat production under climate change, and irrigation as an adaptation measure to improve yield, crop water productivity (CWP), and irrigation water productivity (IWP) in the CRV of Ethiopia. AquaCrop is applied to evaluate the effects of climate change and simulate irrigation as an adaptation measure. The analysis covers the baseline (1981–2020) and future (2026–2095) periods with each period categorized into three rainfall years (wet, normal, and dry). The future period is described using two representatives’ concentration pathways (RCP4.5 and PCP8.5) scenarios. The results under rainfed and future climate conditions show that the winter wheat yield and CWP are projected to be lowered as compared to the baseline period. Most importantly, a significant reduction in wheat yield and CWP is noticed during the dry years (−60% and −80%) compared to the wet years (−30% and −51%) and normal years (−18% and −30%), respectively. As compared to rainfed agriculture, irrigation significantly reduces the risk of wheat yield decline and improves the CWP. Irrigation is also able to improve the CWP of rainfed wheat production ranging from 0.98–1.4 kg/m3 to 1.48–1.56 kg/m3. A projected CWP improvement of 1.1–1.32 kg/m3 under irrigation is possible from 0.87–1.1 kg/m3 under rainfed conditions. The study concludes that optimizing irrigation as a climate-change-adapting strategy in the CRV has a more pronounced positive impact to the rainfed production system, especially for the dry and normal years