Global review reveals how disparate study motivations, analytical designs, and focal ions limit understanding of salinization effects on freshwater animals.

Global salinization of freshwaters is adversely affecting biotic communities and ecosystem processes. We reviewed six decades (1960-2020) of literature published on animal responses to increased salinities across different taxonomic and ecological contexts and identified knowledge gaps. From 585 journal articles, we characterized 5924 responses of mollusks, crustaceans, zooplankton, non-arthropod invertebrates (NAI), insects, fishes, and amphibians to salinization. Insects and fishes were the most studied taxa; Na+ and Cl- were the most studied ions-. Collectively, concentrations of the ions examined typically spanned five orders of magnitude. Species' invasiveness was a key motivation for studying mollusks, crustaceans, and fishes; threats of urbanization and road salts were key motivations for studying NAI, zooplankton, and amphibians. Laboratory studies were more common than field studies for most taxa. Focal life stages in laboratory studies varied widely but juveniles and adults were represented similarly in field studies. Studies of mollusks, NAI, and crustacean focused on adults; studies of zooplankton, insects, fishes, and amphibians focused on juveniles. Organismal- and population-level responses measuring solute uptake, internal chemistry, body condition, or ion concentrations predominated laboratory studies; population- and assemblage-level responses measuring abundance, spatial distribution, or assemblage composition predominated field studies. Negative responses to salinization predominated but positive and unimodal responses were apparent across all taxa and organizational levels. Key topics for further research include a) salinity responses by more taxa, b) responses to especially toxic ions (i.e., potassium, bicarbonate, sulfate, magnesium), c) mechanisms causing positive and unimodal responses, d) traits underpinning responses, e) effects transcending organizational levels, f) ion-specific response thresholds, and g) interactions between salinity and other stressors. Our review suggests inter-taxa variation in sensitivity to salinization reflects occurrence of certain biological traits, including gill-breathing, semi-permeable skin, multiple life stages, and limited mobility. We propose a traits-based framework to predict salinization sensitivity from shared traits. This evolutionary approach could inform management aimed at preventing or reducing adverse impacts of freshwater salinization.

Hip and Knee Arthroplasty Outcomes for Nonagenarian Patients.

INTRODUCTION: Studies have previously reported higher complication rates in elective total joint arthroplasty (TJA) for nonagenarians compared with younger cohorts. The purpose of this study was to assess whether nonagenarians were still at increased risk of complications and hospital readmissions by answering three questions: (1) Do nonagenarians have an increased risk of medical complications after TJA compared with octogenarians and septuagenarians? (2) Do nonagenarians have an increased risk of surgical complications after TJA compared with octogenarians and septuagenarians? (3) Do nonagenarians have an increased risk of hospital readmission after TJA compared with octogenarians and septuagenarians? METHODS: A total of 174 patients undergoing primary TJA between 2010 and 2017 were included; 58 nonagenarians (older than 90 years) were matched with 58 octogenarians (age 80 to 84 years) and 58 septuagenarians (age 70 to 74). Groups were matched by sex, diagnosis, surgeon, surgical joint, and year of surgery. Within each group, 31 patients (53%) underwent total hip arthroplasty and 27 patients (47%) underwent total knee arthroplasty. Comorbidities, American Society of Anesthesiologists physical status scores, and Charlson Comorbidity Index scores were captured preoperatively. Complications and readmissions occurring within 90 days postoperatively were evaluated. RESULTS: Nonagenarians had the highest rate of medical complications (33%) compared with octogenarians (14%) and septuagenarians (3%) (P < 0.001). Rates of surgical complications were not statistically different among nonagenarians (12%), octogenarians (9%), and septuagenarians (10%) (P = 0.830). Rates of hospital readmission were highest in nonagenarian patients (11%), but not statistically different compared with octogenarians (5%) or septuagenarians (2%) (P = 0.118). CONCLUSION: Nonagenarians were 3.1 times more likely to have a complication after TJA. The incidence of medical complications was highest in nonagenarians compared with octogenarians and septuagenarians, but rates of orthopaedic complications were similar. Nonagenarians who elect to proceed with TJA should be informed that they have an increased risk of postoperative medical complications compared with younger patients undergoing the same operation. LEVEL OF EVIDENCE: Level III, Therapeutic Study.

No Difference in Blood Loss and Risk of Transfusion Between Patients Treated with One or Two Doses of Intravenous Tranexamic Acid After Simultaneous Bilateral TKA.

BACKGROUND: Tranexamic acid (TXA) is often used to prevent excessive blood loss during bilateral TKA. Although it diminishes blood loss, TXA may have a potentially elevated thrombogenic risk with extra, unnecessary doses of TXA in this high-risk population. To date, the most efficacious dosing protocol in this setting has not yet been ascertained. QUESTIONS/PURPOSES: We compared one versus two doses of intravenous TXA in the setting of same-day bilateral TKA in terms of (1) perioperative blood loss that occurred during the hospital stay, (2) transfusion usage during the hospital stay, and (3) major complications occurring within 30 days of surgery. METHODS: Between August 2013 and October 2016, 309 patients underwent simultaneous bilateral TKA performed by one of five attending surgeons. During that time, indications for same-day bilateral TKA included bilateral knee pathology in which each knee was independently indicated for TKA and the patient preferred bilateral simultaneous TKAs versus staged bilateral surgeries. Patients who had cardiac disease or an American Society for Anesthesiologists physical classification score of greater than 2 were not generally indicated for bilateral simultaneous TKAs. After preoperative clearance from the primary physician and/or specialists as necessary, the decision for bilateral TKA was at the judgment of the operating surgeons. Input from anesthesia occurred at the time of the surgery as the procedure was performed in a sequential fashion allowing for the surgery to be restrained to a single limb if anesthesia identified concerns at the completion of the first TKA. The current retrospective, comparative series compared generally sequential groups in terms of TXA usage. Between August 2013 and July 2015, we used two TXA doses. Patients received 1 g of intravenous TXA as a bolus immediately after the last tourniquet release and were given a 1-g intravenous bolus 6 hours after the initial dose. A total of 167 patients were treated with this approach, of whom 96% (161) are fully analyzed here. Between August 2015 and October 2016, our approach changed to a single TXA dose. The dosing regimen change occurred as a group decision for change of practice and occurred mid-year to coincide with the fellowship year cycle. Patients received a 1-g bolus of intravenous TXA immediately after the final tourniquet release. A total of 105 patients were treated with this approach, of whom 89% (93) are fully analyzed here. An additional 37 patients were excluded because they did not receive any TXA because of a medical contraindication such as history of venous thromboembolism, history of thrombotic stroke, cardiac stent in the past 2 years, atrial fibrillation, or long-term anticoagulation therapy. We compared patients who received one versus two doses in terms of blood loss, transfusion usage, and 30-day major complications. The mean age was 65 years for patients receiving one dose and 67 years for patients receiving two doses (p = 0.17). The one-dose group comprised 67% (62 of 93) women and the two-dose group comprised 61% (98 of 161) women (p = 0.36). Blood loss was defined as change in the hemoglobin level (the last recorded value before discharge subtracted from the preoperative value). During the study period, the decision to transfuse was based on a hemoglobin level less than 8.0 g/dL or at higher levels for symptomatic patients, patients with cardiac disease, or at the discretion of the attending surgeon. We defined complications as major medical events that included cerebrovascular accidents, myocardial infarction, deep vein thrombosis, and pulmonary embolism. RESULTS: With the numbers available, there was no difference in blood loss between patients treated with one and those treated with two doses of TXA (mean hemoglobin decrease -3.5 ± 1.2 g/dL versus -3.5 ± 1.0 g/dL, respectively; mean difference 0.03 g/dL [95% CI -0.2 to 0.3 g/dL]; p = 0.80). No patient in either group received a transfusion. There was no difference in the proportion of patients in either group who experienced a cerebrovascular accident (0% [0 of 93] versus 1% [1 of 161]; p > 0.99), deep vein thrombosis (1% [1 of 93] versus 0% [0 of 161]; p = 0.37), or pulmonary embolism (1% [1 of 93] versus 1% [1 of 161]; p > 0.99). No patient in either the one-dose or two-dose TXA groups experienced a myocardial infarction. CONCLUSION: The findings of this study suggest that a single dose of intravenous TXA may be adequate to control excessive blood loss and reduce blood transfusion in simultaneous bilateral TKA. Despite its short half-life, TXA still appears to be effective in this demanding procedure without requiring prolonged plasma concentrations obtained from multiple doses. Additional high-quality studies are still needed to determine the most appropriate dosing regimen. LEVEL OF EVIDENCE: Level III, therapeutic study.

Time marches on, but do the causal pathways driving instream habitat and biology remain consistent?

Stream ecosystems are complex networks of interacting terrestrial and aquatic drivers. To untangle these ecological networks, efforts evaluating the direct and indirect effects of landscape, climate, and instream predictors on biological condition through time are needed. We used structural equation modeling and leveraged a stream survey program to identify and compare important predictors driving condition of benthic macroinvertebrate and fish assemblages. We used data resampled 14 years apart at 252 locations across Maryland, USA. Sample locations covered a wide range of conditions that varied spatiotemporally. Overall, the relationship directions were consistent between sample periods, but their relative strength varied temporally. For benthic macroinvertebrates, we found that the total effect of natural landscape (e.g., elevation, longitude, latitude, geology) and land use (i.e., forest, development, agriculture) predictors was 1.4 and 1.5 times greater in the late 2010s compared to the 2000s. Moreover, the total effect of water quality (e.g., total nitrogen and conductivity) and habitat (e.g., embeddedness, riffle quality) was 1.2 and 4.8 times lower in the 2010s, respectively. For fish assemblage condition, the total effect of land use-land cover predictors was 2.3 times greater in the 2010s compared to the 2000s, while the total effect of local habitat was 1.4 times lower in the 2010s, respectively. As expected, we found biological assemblages in catchments with more agriculture and urban development were generally comprised of tolerant, generalist species, while assemblages in catchments with greater forest cover had more-specialized, less-tolerant species (e.g., Ephemeroptera, Plecoptera, and Trichoptera taxa, clingers, benthic and lithophilic spawning fishes). Changes in the relative importance of landscape and land-use predictors suggest other correlated, yet unmeasured, proximal factors became more important over time. By untangling these ecological networks, stakeholders can gain a better understanding of the spatiotemporal relationships driving biological condition to implement management practices aimed at improving stream condition.

Warmer temperatures interact with salinity to weaken physiological facilitation to stress in freshwater fishes.

Management of stressors requires an understanding of how multiple stressors interact, how different species respond to those interactions and the underlying mechanisms driving observed patterns in species' responses. Salinization and rising temperatures are two pertinent stressors predicted to intensify in freshwater ecosystems, posing concern for how susceptible organisms achieve and maintain homeostasis (i.e. allostasis). Here, glucocorticoid hormones (e.g. cortisol), responsible for mobilizing energy (e.g. glucose) to relevant physiological processes for the duration of stressors, are liable to vary in response to the duration and severity of salinization and temperature rises. With field and laboratory studies, we evaluated how both salinity and temperature influence basal and stress-reactive cortisol and glucose levels in age 1+ mottled sculpin (Cottus bairdii), mountain sucker (Catostomus platyrhynchus) and Colorado River cutthroat trout (Oncorhynchus clarki pleuriticus). We found that temperature generally had the greatest effect on cortisol and glucose concentrations and the effect of salinity was often temperature dependent. We also found that when individuals were chronically exposed to higher salinities, baseline concentrations of cortisol and glucose usually declined as salinity increased. Reductions in baseline concentrations facilitated stronger stress reactivity for cortisol and glucose when exposed to additional stressors, which weakened as temperatures increased. Controlled temperatures near the species' thermal maxima became the overriding factor regulating fish physiology, resulting in inhibitory responses. With projected increases in freshwater salinization and temperatures, efforts to reduce the negative effects of increasing temperatures (i.e. increased refuge habitats and riparian cover) could moderate the inhibitory effects of temperature-dependent effects of salinization for freshwater fishes.

Multiple approaches to surface water quality assessment provide insight for small streams experiencing oil and natural gas development.

Historic, current, and future oil and natural gas development can affect water quality in streams flowing through developed areas. We compared small stream drainages in a semiarid landscape with varying amounts of disturbance from oil and natural gas development to examine potential effects of this development on surface water quality. We used physical, chemical, and biological approaches to assess water quality and found several potential avenues of degradation. Surface disturbance likely contributed to elevated suspended sediment concentrations and spill history likely led to elevated stream polycyclic aromatic hydrocarbon concentrations. In combination, these environmental stressors could explain the loss of aquatic macroinvertebrate taxon at sites highly affected by oil and natural gas development. Our results provide insight into advantages and disadvantages of approaches for assessing surface water quality in areas affected by oil and natural gas development. Integr Environ Assess Manag 2019;00:000-000. © 2019 SETAC.

Activity-related Changes in Cobalt Levels in a Total Hip with a Modular Femoral Stem: A Case Report.

INTRODUCTION: Femoral neck modularity in total hip arthroplasty (THA) affords the surgeon the ability to optimize femoral neck length, offset, and version, thereby theoretically improving restoration of patient anatomy and biomechanics. The effect of activity on serum metal ion levels in patients with a THA with a mixed-metal modular neck design has not yet been described. CASE REPORT: A 63-year-old male underwent THA utilizing a femoral stem with a mixed-metal modular femoral neck. After the stem was voluntarily recalled, he was indicated to be monitored for manifestations ofmodular junction corrosion and development of adverse local tissue reactions (ALTR). An association between activity levels and serial serum cobalt levels was demonstrated. CONCLUSION: In this patient with a THA incorporating a mixed-metal modular femoral neck, modification of activity intensity may have played a role in altered corrosion generation, as indicated by serum metal ion levels. In turn, this may play a role in the progression of ALTR.

Ceramic liner fracture and impingement in total hip arthroplasty.

BACKGROUND: Ceramic-on-ceramic bearing surfaces were developed to provide an alternate to metal-on-polyethylene to decrease wear-induced osteolysis in total hip arthroplasty patients. In an effort to decrease the risk of ceramic acetabular component fracture or damage during implantation, a raised metal rim was added. QUESTIONS/PURPOSES: How many fractures or impingements have occurred in our population of patients with ceramic liners with raised rims? METHODS: With IRB-approved consent, a case series was reviewed from a single center registry and 4 of 169 patients were identified who had revision hip surgery with the ceramic liner with a raised metal rim: one for ceramic liner fracture and three for metallosis, pain, and squeaking. Implant alignment and operative findings were reviewed. RESULTS: One ceramic liner fracture and three cases of metallosis from impingement of the femoral neck on the posterior elevated metal rim of the acetabular liner were observed at revision. The femoral neck in each patient had a divot that corresponded to a divot in the posterosuperior liner rim. Three of the four patients had audible squeaking or clicking prior to revision. A total of 3% of patients in this series had clinically significant impingement with this implant type. CONCLUSION: Acoustic phenomenon in a ceramic on ceramic bearing surface should be investigated with a cross-table lateral radiograph to evaluate component position. If symptomatic impingement is demonstrated, revision should be considered to avoid failure from metallosis or fracture.

Outcome and range of motion using a high-flexion cruciate-retaining TKA.

Increased knee flexion after total knee arthroplasty (TKA) may contribute to patients' increased satisfaction and more active lifestyles. This study evaluated a TKA component designed for high flexion (more than 125°). The design features an anatomic sagittal femoral radius with short, flared femoral condyles to allow for femoral rollback. Fifty TKA procedures in 47 patients were evaluated prospectively regarding clinical outcomes using Knee Society knee and function scores, Short Form 12 physical component scores, and flexion measured clinically and by digital lateral supine active flexion radiographs. Preoperative and 1-year postoperative radiographs were analyzed by an independent observer. Mean maximum flexion measured clinically was 115° preoperatively and 120° one year postoperatively, with 76% of TKAs achieving more than 120° and 44% achieving more than 125°. Sex, body mass index, and preoperative flexion were not predictors of postoperative flexion. Mean flexion by radiograph was 108° preoperatively and 111° one year postoperatively, with 31% of knees achieving more than 120° and 14% more than 125°. Mean Knee Society knee and function scores and the Short Form 12 physical component scores were 52, 55, and 32 preoperatively, respectively, and 89, 77, and 40 one year postoperatively, respectively. Of the 50 knees, 84% had improvement in their Knee Society function scores, and 76% had improvement in their Short Form 12 physical component scores. The study revealed evidence of increased early postoperative flexion with the use of a cruciate-retaining high-flexion TKA design.

Incidence of 'squeaking' after ceramic-on-ceramic total hip arthroplasty.

UNLABELLED: The incidence of hip "squeak" associated with ceramic-on-ceramic bearings has been variably reported, ranging from 0.7% to 20.9%. We determined the patients' perception of squeaking in 306 patients (336 hips) in whom ceramic-on-ceramic total hip arthroplasties (THAs) were performed between 1997 and 2005. A questionnaire regarding hip noise was obtained by telephone. With a minimum followup of 2 years (mean, 3.9 years; range, 2-10 years), 290 patients (320 or 95% of the THAs) completed the questionnaire. Patients reported hip noise in 55 of the 320 THAs (17%); noise was perceived as squeak in 32 of the 320 (10%). Most squeaking hips (29 of 32) were pain-free and symptom-free. One patient was unhappy with his squeaking hip without pain. Our data suggest a much higher incidence of squeak as perceived by patients than previously reported. LEVEL OF EVIDENCE: Level II, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Early dislocation rate in ceramic-on-ceramic total hip arthroplasty.

Wear debris from metal-on-polyethylene articulation in conventional total hip arthroplasty (THA) may limit THA longevity. Bearing surfaces made of modern ceramic material, with high wear resistance and low fracture risk, have the potential to extend the longevity of THA and make the procedure more suitable for young, active patients. Concerns regarding a ceramic-on-ceramic bearing surface have included potential for a higher incidence of dislocation caused by limited modular neck length and liner options. This prospective study assessed the early dislocation incidence for a ceramic-on-ceramic THA system. Out of the 336 consecutive ceramic-on-ceramic THA performed at our institution over an 8-year (1997-2005) period, 2 (0.6%) sustained dislocation during, and none after, the first postoperative year. Both dislocations were treated with closed reduction. No component fracture or revision for any reason has occurred in this series.

Portable compression device and low-molecular-weight heparin compared with low-molecular-weight heparin for thromboprophylaxis after total joint arthroplasty.

This preliminary prospective study to determine the rate of deep venous thrombosis (DVT) examined 277 patients undergoing total knee or total hip arthroplasty (TKA or THA) who were randomized to use a portable, continuous enhanced circulation therapy (CECT) compression device and low-molecular-weight heparin (LMWH) or to receive LMWH alone. Patients were screened for DVT using duplex ultrasound at hospital discharge and followed clinically for 3 months. In TKA, 5 DVTs (6.6%) occurred in the CECT + LMWH group compared with one pulmonary embolism and 14 DVTs (19.5%) in the LMWH group (P = .018). In THA, 1 DVT (1.5%) occurred in the CECT + LMWH group and 2 DVTs (3.4%) occurred in the LMWH group. This preliminary study demonstrated significant reduction in rate of DVT after TKA when the CECT device was combined with LMWH.

The use of reinfusion drains after total knee arthroplasty in patients treated with low molecular weight heparin for thromboembolic prophylaxis.

The effect of closed-suction drainage with red-cell reinfusion on patients receiving low molecular weight heparin (LMWH) prophylaxis after total knee arthroplasty (TKA) has not been previously studied. Therefore, our goals were to determine the effect of reinfusion drains and LMWH on allogeneic transfusions and wound complications after TKA by comparing patients treated with and without drains. Overall, transfusion rates were lower in the drain group (40% vs 15%, P=.04). Patients with reinfusion drains had a significantly higher rate of allogeneic transfusion (15.8%) than those predonating autologous blood and no drain (5.4%, P=.0003). The drain group had lower rates of wound complications (P=not significant). We were unable to demonstrate the efficacy of red-cell reinfusion as a substitute for autologous donation in TKA.

The efficacy of a single daily dose of enoxaparin for deep vein thrombosis prophylaxis following total knee arthroplasty.

Deep vein thrombosis (DVT) is a major risk following total knee arthroplasty (TKA). This prospective outcomes study evaluates the efficacy of enoxaparin 40 mg once daily for 7 days after TKA, by documenting symptomatic and asymptomatic outcomes using bilateral lower extremity duplex ultrasound upon hospital discharge and on postoperative day 21 (+/-2). In 60 extremities, duplex ultrasound demonstrated a DVT prevalence of 16.7% (10) on the day of discharge and of 11.7% (7) on postoperative day 21. No new DVT or propagation of distal to proximal DVT were noted. For this small cohort, enoxaparin 40 mg daily demonstrates effective prophylaxis for DVT in TKA patients.