Patients Who Have a Prior History of Pulmonary Embolism Require Increased Postoperative Care Following Total Joint Arthroplasty.

BACKGROUND: This study examined the effect of prior pulmonary embolism (PE) on total joint arthroplasty (TJA) outcomes. METHODS: We reviewed patients who had a prior PE undergoing TJA at a single tertiary medical center between January 1, 2012 and January 1, 2021. There were 177 TJA patients who had a prior PE who underwent 1:3 propensity-matching to patients without a history of prior PE. Bivariable and multivariable analyses were performed. Changes over time were evaluated. RESULTS: Patients undergoing total knee arthroplasty who had a prior PE had more complications (25.3% versus 2.0%, P < .001), and postoperative PE (17.3% versus 0.0%, P < .001).and longer hospitalizations (3.15 versus 2.32 days, P = .006). Patients undergoing total hip arthroplasty who had a prior PE demonstrated more complications (14.7% versus 1.77%, P < .001) more postoperative PE (17.3% versus 0.0%, P < .001), and longer hospitalizations (3.30 versus 2.11 days, P < .001). Over the study, complication rates and hospitalizations lengths remained elevated in patients who had a prior PE. On multivariate analyses, prior PE was associated with longer hospitalizations (ß: 0.67, P = .015) and increased complications (odds ratio [OR]: 9.44, P < .001) among total hip arthroplasty patients. Total knee arthroplasty patients had increased readmission (OR: 4.89, P = .003) and complication rates (OR: 21.4, P < .001). CONCLUSIONS: Patients undergoing TJA who had a prior PE are at higher risk of requiring postoperative care. Therefore, thorough preoperative evaluation must be implemented, especially in clinical environments lacking resources for acute care escalation.

Patients Who Have Pre-Existing Atrial Fibrillation Require Increased Postoperative Care Following Total Joint Arthroplasty.

BACKGROUND: Approximately 9% of total joint arthroplasty (TJA) patients have pre-existing atrial fibrillation (AF). This study examined the effect of pre-existing AF on TJA outcomes. METHODS: We conducted a 1:3 propensity match of 545 TJA patients who have pre-existing AF to TJA patients who do not have AF at a tertiary care center between January 1st, 2012, and January 1st, 2021. Bivariate and multivariate regressions were performed. Changes over time were evaluated. RESULTS: Patients undergoing total knee arthroplasty (TKA) who have pre-existing AF, experienced more post-operative AFs (P < .001), acute kidney injuries (P = .026), post-operative complications (POC) (P < .001), and 30-day readmissions (P = .036). Patients undergoing total hip arthroplasty (THA) who have pre-existing AF experienced more post-operative AFs (P < .001), pulmonary embolisms (P < .001), increased estimated blood losses (P = .007), more blood transfusions (P = .002), more POCs (P < .001), and longer lengths of stay (LOS) (P < .002). Over time, POC and LOS decreased in both groups, but remained increased in TJA patients who have pre-existing AF. Multivariate analyses of TKA patients showed an increased odds ratio (OR) of any POCs (P < .001), while THA patients had an increased OR of any POCs (P = .01), and LOS (P = .002). CONCLUSION: Patients who have pre-existing AF undergoing TJA have more POCs. TKA patients have more readmissions. THA patients have longer LOS. These findings demonstrate the importance of enhanced peri-operative medical management in patients who have pre-existing AF undergoing TJA.

The Potential Value of Performing Preoperative Urinalysis Prior to Total Knee Arthroplasty.

BACKGROUND: Although the practice of checking a urinalysis prior to elective total knee arthroplasty (TKA) is relatively common, very little has been reported on the association between a preoperative urinary tract infection (UTI) and adverse events in primary TKA. The goal of this study is to investigate the risk of postoperative complication following TKA as it relates to preoperative UTI. METHODS: Patients undergoing TKA were queried in the National Surgical Quality Improvement Program. Morbid events were classified as minor (transfusion, pneumonia, wound dehiscence, UTI, and renal insufficiency) and serious (wound infection, thromboembolic event, renal failure, myocardial infarction, prolonged ventilation, unplanned intubation, sepsis, and death). Risk factors for adverse events were analyzed in both univariate and multivariate fashion. RESULTS: A total of 203,851 patients undergoing TKA met inclusion criteria and 507 patients had a UTI present at time of surgery (UTI PATOS). A propensity matched analysis controlling for age, gender, body mass index, operative year, and American Society of Anesthesiologists score identified 507 patients without a UTI PATOS to serve as the control group. Following adjustment for baseline characteristics, operative year, and American Society of Anesthesiologists score, UTI PATOS was associated with increased risk for serious adverse events (odds ratio [OR] 2.746, 95% confidence interval [CI] 1.546-4.878, P = .0006), occurrence of any morbid event (OR 1.894, 95% CI 1.299-2.761, P = .0009), and reoperation (OR 4, 95% CI 2.592-6.169, P < .0001). CONCLUSION: This study suggests that a UTI present at time of TKA increases the risk of multiple postoperative complications and reoperation.

Assessment of Psychological Factors in Short-Stay Total Hip Arthroplasty Protocol.

BACKGROUND: Several variables are known to correlate with the successful completion of short-stay total hip arthroplasty (THA) protocols. The role of psychological factors remains unclear. We investigated the interaction between patient-reported measures of psychological fitness and successful completion of a short-stay THA protocol. METHODS: We performed a prospective cohort study of patients undergoing elective anterior total hip arthroplasty enrolled in a short-stay protocol (success defined as LOS ≤1 midnight versus failed, LOS >1 midnight). Psychological fitness was measured using the Patient-Reported Outcomes Measurement Information System (PROMIS) domains for self-efficacy, depression, anxiety, emotional support, and the ability to participate in social roles. PROMIS scores, patient demographics, and surgical factors were assessed for a relationship with failure to complete short-stay protocol. RESULTS: Patients that failed to complete the short-stay protocol had higher mean pre-operative PROMIS depression scores (50.8 vs 47.1, P = .025) and anxiety scores (53.6 vs 49.2, P = .008) and higher postoperative PROMIS depression (48.19 vs 43.49, P = .003) and anxiety scores (51.7 vs 47.1, P = .01). Demographic and surgical variables did not correlate with the successful completion of the short-stay protocol. That seventy-six percent of the patients did not adhere to the short-stay protocol was due to the inability to complete a physical therapy standardized safety assessment. CONCLUSION: Higher levels of preoperative and postoperative anxiety and depression in otherwise psychologically healthy patients, is associated with an increased risk of failure to complete a short-stay protocol following THA. Targeted interventions are needed to facilitate rapid recovery in patients with psychological barriers to early mobilization.

Transport of N and P in U.S. streams and rivers differs with land use and between dissolved and particulate forms.

We used a recently published, open-access data set of U.S. streamwater nitrogen (N) and phosphorus (P) concentrations to test whether watershed land use differentially influences N and P concentrations, including the relative availability of dissolved and particulate nutrient fractions. We tested the hypothesis that N and P concentrations and molar ratios in streams and rivers of the United States reflect differing nutrient inputs from three dominant land-use types (agricultural, urban and forested). We also tested for differences between dissolved inorganic nutrients and suspended particulate nutrient fractions to infer sources and potential processing mechanisms across spatial and temporal scales. Observed total N and P concentrations often exceeded reported thresholds for structural changes to benthic algae (58, 57% of reported values, respectively), macroinvertebrates (39% for TN and TP), and fish (41, 37%, respectively). The majority of dissolved N and P concentrations exceeded threshold concentrations known to stimulate benthic algal growth (85, 87%, respectively), and organic matter breakdown rates (94, 58%, respectively). Concentrations of both N and P, and total and dissolved N:P ratios, were higher in streams and rivers with more agricultural and urban than forested land cover. The pattern of elevated nutrient concentrations with agricultural and urban land use was weaker for particulate fractions. The % N contained in particles decreased slightly with higher agriculture and urbanization, whereas % P in particles was unrelated to land use. Particulate N:P was relatively constant (interquartile range = 2-7) and independent of variation in DIN:DIP (interquartile range = 22-152). Dissolved, but not particulate, N:P ratios were temporally variable. Constant particulate N:P across steep DIN:DIP gradients in both space and time suggests that the stoichiometry of particulates across U.S. watersheds is most likely controlled either by external or by physicochemical instream factors, rather than by biological processing within streams. Our findings suggest that most U.S. streams and rivers have concentrations of N and P exceeding those considered protective of ecological integrity, retain dissolved N less efficiently than P, which is retained proportionally more in particles, and thus transport and export high N:P streamwater to downstream ecosystems on a continental scale.

Risk Factors for Greater Than 24-Hour Length of Stay After Primary Total Knee Arthroplasty.

BACKGROUND: Recently, the Center for Medicare Services removed total knee arthroplasty (TKA) from the inpatient-only procedure list. The purpose of this study is to assess the role of demographics, medical comorbidities, and postsurgical complications in predicting safe discharge to home within 24 hours after TKA. METHODS: Patients undergoing primary TKA between 2011 and 2016 were identified in the American College of Surgeons National Surgical Quality Improvement Program. Patients were grouped into those whose length of stay (LOS) was less than 24 hours after surgery vs those greater than 24 hours. Demographics, preoperative comorbidities, operative variables, and postoperative adverse events were studied as risk factors for LOS greater than 24 hours. RESULTS: A total of 210,075 patients undergoing primary TKA met the inclusion criteria, and of those, 18,134 (8.6%) patients were discharged within 24 hours postoperatively. In a risk-adjusted multivariate analysis, patients with increasing age, obesity, preoperative comorbidities of smoking, diabetes, dyspnea, chronic obstructive pulmonary disease, hypertension, bleeding disorder, corticosteroid use preoperatively, and dependent functional status conferred a greater risk for discharge greater than 24 hours. Male gender, spinal anesthesia, and monitored anesthesia care were protective against LOS greater than 24 hours. CONCLUSION: This study suggests that dependent functional status, preoperative comorbidities, and postoperative complications are all associated with a LOS greater than 24 hours after TKA. Surgeons and patients should be aware of the clinical and demographic variables associated with risk for LOS greater than 24 hours when considering outpatient status for patients undergoing TKA.

Which Postoperative Day After Total Joint Arthroplasty Are Catastrophic Events Most Likely to Occur?

BACKGROUND: Despite lacking granularity, large database registries can help provide important information on rare outcomes following total joint arthroplasty (TJA). In an era of short stay and outpatient arthroplasty, an awareness of the timeframe for most common catastrophic complications can help providers maintain an appropriate degree of suspicion for these significant events. METHODS: Patients undergoing primary TJA between 2011 and 2016 were identified in the National Surgical Quality Improvement Program and queried for 4 adverse postoperative outcomes: pulmonary embolism (PE), myocardial infarction or cardiac arrest, cerebrovascular accident, and death. The timing of postoperative events was compared, and also their association with medical comorbidities and timing in inpatient vs outpatient arthroplasty. RESULTS: A total of 341,601 patients met inclusion criteria. Of them, 1631 (0.48%) patients sustained a postoperative PE, 1033 (0.3%) patients had a cardiac event, 304 patients had a cerebrovascular accident (0.09%), and 608 (0.18%) patients expired. Greater than 60% of all these complications occurred between postoperative days 0 and 5, including 65% of PE. On postoperative day 0, a catastrophic event is 13 times more likely to be a cardiac event (80.7%) compared to a PE (6%). However, by postoperative day 1, a cardiac event (41.2%) is only 1.03 times more likely than a PE (40%) and by postoperative day 2, a PE (62%) is twice as likely as a cardiac event (30%). CONCLUSION: Risk assessment for catastrophic event and timeliness of occurrence may guide providers to recommend enhanced observation for specific patients undergoing TJA.

Nutrients and temperature additively increase stream microbial respiration.

Rising temperatures and nutrient enrichment are co-occurring global-change drivers that stimulate microbial respiration of detrital carbon, but nutrient effects on the temperature dependence of respiration in aquatic ecosystems remain uncertain. We measured respiration rates associated with leaf litter, wood, and fine benthic organic matter (FBOM) across seasonal temperature gradients before (PRE) and after (ENR1, ENR2) experimental nutrient (nitrogen [N] and phosphorus [P]) additions to five forest streams. Nitrogen and phosphorus were added at different N:P ratios using increasing concentrations of N (~80-650 µg/L) and corresponding decreasing concentrations of P (~90-11 µg/L). We assessed the temperature dependence, and microbial (i.e., fungal) drivers of detrital mass-specific respiration rates using the metabolic theory of ecology, before vs. after nutrient enrichment, and across N and P concentrations. Detrital mass-specific respiration rates increased with temperature, exhibiting comparable activation energies (E, electronvolts [eV]) for all substrates (FBOM E = 0.43 [95% CI = 0.18-0.69] eV, leaf litter E = 0.30 [95% CI = 0.072-0.54] eV, wood E = 0.41 [95% CI = 0.18-0.64] eV) close to predicted MTE values. There was evidence that temperature-driven increased respiration occurred via increased fungal biomass (wood) or increased fungal biomass-specific respiration (leaf litter). Respiration rates increased under nutrient-enriched conditions on leaves (1.32×) and wood (1.38×), but not FBOM. Respiration rates responded weakly to gradients in N or P concentrations, except for positive effects of P on wood respiration. The temperature dependence of respiration was comparable among years and across N or P concentration for all substrates. Responses of leaf litter and wood respiration to temperature and the combined effects of N and P were similar in magnitude. Our data suggest that the temperature dependence of stream microbial respiration is unchanged by nutrient enrichment, and that increased temperature and N + P availability have additive and comparable effects on microbial respiration rates.

Statistical Methods Dictate the Estimated Impact of Body Mass Index on Major and Minor Complications After Total Joint Arthroplasty.

BACKGROUND: Elevated body mass index (BMI) is considered a risk factor for complications after THA and TKA. Stakeholders have proposed BMI cutoffs for those seeking arthroplasty. The research that might substantiate BMI cutoffs is sensitive to the statistical methods used, but the impact of the statistical methods used to model BMI has not been defined. QUESTIONS/PURPOSES: (1) How does the estimated postarthroplasty risk of minor and major complications vary as a function of the statistical method used to model BMI? (2) What is the prognostic value of BMI for predicting complications with each statistical method? METHODS: Using the American College of Surgeons National Surgical Quality Improvement Program from 2005 to 2012, we investigated the impact of BMI on major and minor complication risk for THA and TKA. Analyses were weighted with covariate-balancing propensity scores to account for the differential rate of comorbidities across the range of BMI. We specified BMI in two ways: (1) categorically by World Health Organization (WHO) BMI classes; and (2) as a smooth, continuous variable using splines. Models of risk for major complications (deep surgical site infection [SSI], pulmonary embolism, stroke, cardiac arrest, myocardial infarction, wound disruption, implant failure, unplanned intubation, > 48 hours on a ventilator, acute renal insufficiency, coma, sepsis, reoperation, or mortality) and minor complications (superficial SSI, pneumonia, urinary tract infection, deep vein thrombosis, or peripheral nerve injury) were constructed and were adjusted for confounding variables known to correlate with complications (eg, American Society of Anesthesiologists classification). Results were compared for different specifications of BMI. Receiver operating characteristic (ROC) curves were compared to determine the additive prognostic value of BMI. RESULTS: The type of BMI parameterization leads to different assessments of risk of postarthroplasty complications for BMIs > 30 kg/m and < 20 kg/m with the spline specification showing better fit in all adjusted models (Akaike Information Criteria favors spline). Modeling BMI categorically using WHO classes indicates that BMI cut points of 40 kg/m for TKA or 35 kg/m for THA are associated with higher risks of major complications. Modeling BMI continuously as a spline suggests that risk of major complications is elevated at a cut point of 44 kg/m for TKA and 35 kg/m for THA. Additionally, in these models, risk does not uniformly increase with increasing BMI. Regardless of the method of modeling, BMI is a poor prognosticator for complications with area under the ROC curves between 0.51 and 0.56, false-positive rates of 96% to 97%, and false-negative rates of 2% to 3%. CONCLUSIONS: The statistical assumptions made when modeling the effect of BMI on postarthroplasty complications dictate the results. Simple categorical handling of BMI creates arbitrary cutoff points that should not be used to inform larger policy decisions. Spline modeling of BMI avoids arbitrary cut points and provides a better model fit at extremes of BMI. Regardless of statistical management, BMI is an inadequate independent prognosticator of risk for individual patients considering total joint arthroplasty. Stakeholders should instead perform comprehensive risk assessment and avoid use of BMI as an isolated indicator of risk. LEVEL OF EVIDENCE: Level III, diagnostic study.

The Effect of Smoking on Thirty-Day Postoperative Complications After Total Joint Arthroplasty: A Propensity Score-Matched Analysis.

BACKGROUND: Total joint arthroplasty (TJA) is a highly successful treatment, but is burdensome to the national healthcare budget. National quality initiatives seek to reduce costly complications. Smoking's role in perioperative complication after TJA is less well known. This study aims to identify smoking's independent contribution to the risk of short-term complication after TJA. METHODS: All patients undergoing primary TJA between 2011 and 2012 were selected from the American College of Surgeon's National Surgical Quality Improvement Program's database. Outcomes of interest included rates of readmission, reoperation, mortality, surgical complications, and medical complications. To eliminate confounders between smokers and nonsmokers, a propensity score was used to generate a 1:1 match between groups. RESULTS: A total of 1251 smokers undergoing TJA met inclusion criteria. Smokers in the combined total hip and knee arthroplasty cohort had higher 30-day readmission (4.8% vs 3.2%, P = .041), were more likely to have a surgical complication (odds ratio 1.84, 95% confidence interval 1.21-2.80), and had a higher rate of deep surgical site infection (SSI) (1.1% vs 0.2%, P = .007). Analysis of total hip arthroplasty only revealed that smokers had higher rates of deep SSI (1.3% vs 0.2%, P = .038) and higher readmission rate (4.3% vs 2.2%, P = .034). Analysis of total knee arthroplasty only revealed greater surgical complications (2.8% vs 1.2%, P = .048) and superficial SSI (1.8% vs 0.2%, P = .002) in smokers. CONCLUSION: Smoking in TJA is associated with higher rates of SSI, surgical complications, and readmission.

Differences in Post-Operative Outcome Between Conversion and Primary Total Hip Arthroplasty.

BACKGROUND: The demand for conversion of prior hip surgery to total hip arthroplasty (conversion THA) is likely to increase as a function of increasing US hip fracture burden in addition to its application in managing other conditions. Thus, outcome analysis is warranted to better inform value-based reimbursement schemes in the era of bundled payments. METHODS: Via Current Procedural Terminology codes, the National Surgical Quality Improvement Project data files were queried for all patients who underwent primary THA and conversion of previous hip surgery to THA from 2005 to 2014. To better understand the isolated effect of procedure type on adverse outcomes, primary and conversion cohorts were then propensity-score matched via logistic regression modeling. Comparisons of the study's primary outcomes were drawn between matched cohorts. Statistical significance was defined by a P-value less than or equal to .05. RESULTS: Relative to the primary THA group, the conversion THA group had statistically greater rates of Center Medicare and Medicaid Services (CMS) complications (7.5% vs 4.5%), non-home bound discharge (19.6% vs 14.7%), and longer length of hospital stay. Conversion THA was associated with increased likelihood of CMS complications (odds ratio 1.68, confidence interval 1.39-2.02) and non-home bound discharge (odds ratio 1.41, confidence interval 1.25-1.58). No statistically significant differences in mortality and readmission were detected. CONCLUSION: The elevated risk for CMS-reported complications, increased length of hospital stay, and non-home bound discharge seen in our study of conversion THA indicates that it is dissimilar to elective primary THA and likely warrants consideration for modified treatment within the Comprehensive Care for Joint Replacement structure in a manner similar to THA for fracture.

Quantitative Effect of Pelvic Position on Radiographic Assessment of Acetabular Component Position.

BACKGROUND: Intraoperative fluoroscopy aims to improve component position in total hip arthroplasty. Measurement bias related to image quality, however, has not been quantified. We aim to quantify measurement bias in the interpretation of acetabular component position as a function of pelvis and fluoroscopic beam position in a simulated supine total hip arthroplasty model. METHODS: Posterior-anterior pelvis and hip images were obtained using a previously described pelvic model with known acetabular component position. Pelvic position was varied in 5° increments of pelvis rotation (iliac-obturator) and tilt (inlet-outlet), and in 1 cm increments from beam center in cranial-caudal and medial-lateral planes. Multiple regression analyses were conducted to evaluate the relationship between the resulting bias in interpretation of component position relative to pelvis position. RESULTS: Anteversion and abduction measurement bias increased exponentially with increasing deviation in rotation and tilt. Greater bias occurred for anteversion than for abduction. Hip centered images were less affected by pelvis malposition than pelvis centered images. Deviations of beam center within 5 cm in the coronal plane did not introduce measurement bias greater than 5°. An arbitrarily defined acceptable bias of ±5° for both abduction and anteversion was used to identify a range of optimum pelvic positioning each for hip and pelvis centered imaging. CONCLUSION: Accurate measurement of acetabular component abduction and anteversion, especially anteversion, is sensitive to proper pelvic position relative to the chosen radiographic plane. An acceptable measurement bias of ±5° is achieved when the pelvis is oriented within a newly identified range of optimum pelvic positioning.

Global synthesis of the temperature sensitivity of leaf litter breakdown in streams and rivers.

Streams and rivers are important conduits of terrestrially derived carbon (C) to atmospheric and marine reservoirs. Leaf litter breakdown rates are expected to increase as water temperatures rise in response to climate change. The magnitude of increase in breakdown rates is uncertain, given differences in litter quality and microbial and detritivore community responses to temperature, factors that can influence the apparent temperature sensitivity of breakdown and the relative proportion of C lost to the atmosphere vs. stored or transported downstream. Here, we synthesized 1025 records of litter breakdown in streams and rivers to quantify its temperature sensitivity, as measured by the activation energy (Ea , in eV). Temperature sensitivity of litter breakdown varied among twelve plant genera for which Ea could be calculated. Higher values of Ea were correlated with lower-quality litter, but these correlations were influenced by a single, N-fixing genus (Alnus). Ea values converged when genera were classified into three breakdown rate categories, potentially due to continual water availability in streams and rivers modulating the influence of leaf chemistry on breakdown. Across all data representing 85 plant genera, the Ea was 0.34 ± 0.04 eV, or approximately half the value (0.65 eV) predicted by metabolic theory. Our results indicate that average breakdown rates may increase by 5-21% with a 1-4 °C rise in water temperature, rather than a 10-45% increase expected, according to metabolic theory. Differential warming of tropical and temperate biomes could result in a similar proportional increase in breakdown rates, despite variation in Ea values for these regions (0.75 ± 0.13 eV and 0.27 ± 0.05 eV, respectively). The relative proportions of gaseous C loss and organic matter transport downstream should not change with rising temperature given that Ea values for breakdown mediated by microbes alone and microbes plus detritivores were similar at the global scale.

The Impact of Metabolic Syndrome on 30-Day Complications Following Total Joint Arthroplasty.

BACKGROUND: The arthroplasty population increasingly presents with comorbid conditions linked to elevated risk of postsurgical complications. Current quality improvement initiatives require providers to more accurately assess and manage risk presurgically. In this investigation, we assess the effect of metabolic syndrome (MetS), as well as the effect of body mass index (BMI) within MetS, on the risk of complication following hip and knee arthroplasty. METHODS: We queried the American College of Surgeons National Surgical Quality Improvement Program database for total hip or knee arthroplasty cases. Thirty-day rates of Centers for Medicare and Medicaid Services (CMS)-reportable complications, wound complications, and readmissions were compared between patients with and without a diagnosis of MetS using multivariate logistic regression. Arthroplasty cases with a diagnosis of MetS were further stratified according to World Health Organization BMI class, and the role of BMI within the context of MetS was assessed. RESULTS: Of the 107,117 included patients, 11,030 (10.3%) had MetS. MetS was significantly associated with CMS complications (odds ratio [OR] = 1.415; 95% confidence interval [CI], 1.306-1.533; P < .001), wound complications (OR = 1.749; 95% CI, 1.482-2.064; P < .001), and readmission (OR = 1.451; 95% CI, 1.314-1.602; P < .001). When MetS was assessed by individual BMI class, the MetS + BMI >40 group was associated with significantly higher risk of CMS complications, wound complications, and readmission compared to the lower MetS BMI groups. CONCLUSION: MetS is an independent risk factor for CMS-reportable complications, wound complications, and readmission following total joint arthroplasty. The risk attributable to MetS exists irrespective of obesity class and increases as BMI increases.

The Lawrence D. Dorr Surgical Techniques & Technologies Award: Differences in Postoperative Outcomes Between Total Hip Arthroplasty for Fracture vs Osteoarthritis.

BACKGROUND: Hip fracture is an increasingly common expanded indication for total hip arthroplasty (THA) and warrants outcome analysis so as to best inform risk assessment models, public reporting of outcome, and value-based reimbursement schemes. METHODS: The National Surgical Quality Improvement Program data file from 2011 to 2014 was used to identify all patients undergoing THA via current procedural terminology code 27130. Propensity score matching in a 1:5 fashion was used to compare 2 cohorts: THA for osteoarthritis and THA for fracture. Primary outcomes included Centers for Medicare and Medicaid Services (CMS) reportable complications, unplanned readmission, postsurgical length of stay, and discharge destination. χ2 tests for categorical variables and Student t test for continuous variables were used to compare the 2 cohorts and adjusted linear regression analysis used to determine the association between hip fracture and THA outcomes of interest. RESULTS: A total of 58,302 patients underwent elective THA for osteoarthritis and 1580 patients underwent THA for hip fracture. Rates of CMS-reported complications (4.0% vs 10.7%; P < .001), non-homebound discharge (39.8% vs 64.7%; P < .001), readmission (4.7% vs 8.0%; P < .001), and mean days of postsurgical hospital stay (3.2 vs 4.4; P < .001) were greater in the hip fracture cohort. THA for hip fracture was significantly associated with increased risk of CMS-reportable complications (odds ratio [OR], 2.67; 95% confidence interval [CI], 2.17-3.28), non-homebound discharge (OR, 1.73; 95% CI, 1.39-2.15), and readmission (OR, 2.78; 95% CI, 2.46-3.12). CONCLUSION: Our findings support recent advocacy for the exclusion of THA for fracture from THA bundled pricing methodology and public reporting of outcomes.

Convergence of detrital stoichiometry predicts thresholds of nutrient-stimulated breakdown in streams.

Nutrient enrichment of detritus-based streams increases detrital resource quality for consumers and stimulates breakdown rates of particulate organic carbon (C). The relative importance of dissolved inorganic nitrogen (N) vs. phosphorus (P) for detrital quality and their effects on microbial- vs. detritivore-mediated detrital breakdown are poorly understood. We tested effects of experimental N and P additions on detrital stoichiometry (C:N, C:P) and total and microbial breakdown (i.e., with and without detritivorous shredders, respectively) of five detritus types (four leaf litter species and wood) with different initial C : nutrient content. We enriched five headwater streams continuously for two years at different relative availabilities of N and P and compared breakdown rates and detrital stoichiometry to pretreatment conditions. Total breakdown rates increased with nutrient enrichment and were predicted by altered detrital stoichiometry. Streamwater N and P, fungal biomass, and their interactions affected stoichiometry of detritus. Streamwater N and P decreased detrital C:N, whereas streamwater P had stronger negative effects on detrital C:P. Nutrient addition and fungal biomass reduced C:N by 70% and C:P by 83% on average after conditioning, compared to only 26% for C:N and 10% for C:P under pretreatment conditions. Detritus with lowest initial nutrient content changed the most and had greatest increases in total breakdown rates. Detrital stoichiometry was reduced and differences among detritus types were homogenized by nutrient enrichment. With enrichment, detrital nutrient content approached detritivore nutritional requirements and stimulated greater detritivore vs. microbial litter breakdown. We used breakpoint regression to estimate values of detrital stoichiometry that can potentially be used to indicate elevated breakdown rates. Breakpoint ratios for total breakdown were 41 (C:N) and 1518 (C:P), coinciding with total breakdown rates that were ~1.9 times higher when C:N or C:P fell below these breakpoints. Microbial and shredder-mediated breakdown rates both increased when C:N and C:P were reduced, suggesting that detrital stoichiometry is useful for predicting litter breakdown dominated by either microbial or shredder activity. Our results show strong effects of nutrient enrichment on detrital stoichiometry and offer a robust link between a potential holistic nutrient loading metric (decreased and homogenized detrital stoichiometry) and increased C loss from stream ecosystems.

Inter-Rater and Intra-Rater Repeatability and Reliability of EOS 3-Dimensional Imaging Analysis Software.

BACKGROUND: Quantifying ideal component position for the acetabulum and stem during total hip arthroplasty (THA) has been described by many methods. A new imaging method using low-dose digital stereoradiography, the EOS imaging system, is a biplanar low-dose X-ray system that allows for 3-dimensional modeling of lower limbs and semiautomated measurement of pelvic parameters and implant alignment. METHODS: Twenty-five patients who underwent primary THA by a single surgeon between October 2014 and December 2014 were retrospectively selected. Only patients with unilateral THA without associated spine pathologies were included, totaling 16 right hips and 9 left hips. There were 8 men and 17 women in the cohort, with a mean age of 67 years (range, 53-82). Three individuals performed measurements of pelvic parameters and implant alignment on 3 separate occasions. An interclass correlation of >0.75 was accepted as evidence of excellent agreement and a confirmation of measurement reliability. RESULTS: Before reviewing patient radiographs, 4 pelvic phantom models were analyzed using the EOS 3-dimensional software to verify accuracy. All anatomic and implant measurements performed by the 3 independent reviewers showed interobserver and intraobserver agreement with interclass correlation >0.75. CONCLUSION: Three-dimensional modeling of hip implants with the EOS imaging system is a reasonable option for the evaluation of component position after THA.

The Interaction of Obesity and Metabolic Syndrome in Determining Risk of Complication Following Total Joint Arthroplasty.

BACKGROUND: The arthroplasty population is increasingly comorbid, and current quality improvement initiatives demand accurate risk stratification. Metabolic syndrome (MetS) has been identified as a risk factor for adverse events after arthroplasty; however, its interaction with obesity in contributing to risk is unclear. METHODS: A retrospective analysis of all Medicare patients undergoing total hip arthroplasty (THA) and total knee arthroplasty (TKA) at a single institution from 2009 to 2013 investigated the interaction between MetS, body mass index (BMI), and risk for Centers for Medicare and Medicaid Services (CMS)-reportable complications, readmission, and discharge disposition. RESULTS: A total of 1462 patients (942 TKA, 538 THA) were included, of which 16.2% had MetS. Regression analysis found that MetS was significantly related to risk of CMS complications (odds ratio [OR] = 1.96, 95% confidence interval [CI] 1.16-3.31, P = .012) and nonhome discharge (OR = 1.78, 95% CI 1.39-2.27, P < .001), but not readmission (OR = 1.23, 95% CI 0.7-2.18, P = .485). Within the MetS cohort, increasing BMI was not associated with increasing complications (P = .726) or readmissions (P = .206) but was associated with nonhome discharge (OR = 1.191 per unit increase in BMI, 95% CI 1.038-1.246, P = .001). CONCLUSION: MetS increases risk for CMS-reportable complications and nonhome discharge disposition after THA and TKA regardless of BMI. Obesity is of less value than MetS in assessing overall risk for complication after THA and TKA.

Detrital stoichiometry as a critical nexus for the effects of streamwater nutrients on leaf litter breakdown rates.

Nitrogen (N) and phosphorus (P) concentrations are elevated in many freshwater systems, stimulating breakdown rates of terrestrially derived plant litter; however, the relative importance of N and P in driving litter breakdown via microbial and detritivore processing are not fully understood. Here, we determined breakdown rates of two litter species, Acer rubrum (maple) and Rhododendron maximum (rhododendron), before (PRE) and during two years (YR1, YR2) of experimental N and P additions to five streams, and quantified the relative importance of hypothesized factors contributing to breakdown. Treatment streams received a gradient of P additions (low to high soluble reactive phosphorus [SRP]; ~10-85 µg/L) crossed with a gradient of N additions (high to low dissolved inorganic nitrogen [DIN]; ~472-96 µg/L) to achieve target molar N:P ratios ranging from 128 to 2. Litter breakdown rates increased above pre-treatment levels by an average of 1.1-2.2x for maple, and 2.7-4.9x for rhododendron in YR1 and YR2. We used path analysis to compare fungal biomass, shredder biomass, litter stoichiometry (nutrient content as C:N or C:P), discharge, and streamwater temperature as predictors of breakdown rates and compared models containing streamwater N, P or N + P and litter C:N or C:P using model selection criteria. Litter breakdown rates were predicted equally with either streamwater N or P (R2 = 0.57). In models with N or P, fungal biomass, litter stoichiometry, discharge, and shredder biomass predicted breakdown rates; litter stoichiometry and fungal biomass were most important for model fit. However, N and P effects may have occurred via subtly different pathways. Litter N content increased with fungal biomass (N-driven effects) and litter P content increased with streamwater P availability (P-driven effects), presumably via P storage in fungal biomass. In either case, the effects of N and P through these pathways were associated with higher shredder biomass and breakdown rates. Our results suggest that N and P stimulate litter breakdown rates via mechanisms in which litter stoichiometry is an important nexus for associated microbial and detritivore effects.