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Background In January 2018, the Center for Medicare and Medicaid Services (CMS) removed total knee arthroplasty (TKA) from the inpatient-only list. This impacted hospital reimbursement, Comprehensive Joint Replacement (CJR) bundle volumes, and bundle performance. We describe these impacts at an academic teaching hospital. Methods We reviewed CJR bundle data provided by CMS and internal databases to identify the shift in CJR TKA episode volume since January 2018, the impact on postacute care (PAC) utilization rates and readmissions, financial impact to the bundle, and impact on hospital reimbursement. We used data provided to CJR participants, internal hospital sources, and the Medicare Limited Data Set. Results Between 2017 and 2018, CJR TKA episodes decreased from 91 to 51 (44% reduction). Inpatient PAC utilization was significantly higher in 2018 (20% vs 8%). The 90-day readmission rates increased from 5.5% to 12.7%. Average variance to target dropped from 15% to 5%. Average CMS reimbursement for TKA at our institution in 2019 was $14,823 for inpatients and $9299 for outpatients. We experienced $930,463 in decreased reimbursement from January 2018 to September 2019 as a result of the shift from inpatient to outpatient. In addition, we expect $625,143 in decreased incentive payments as higher functioning and lower cost outpatient TKAs are excluded from CJR. Conclusion Although CMS projected a minimal impact on CJR bundle participants, this has not been the case at our institution. We experienced reduced volumes, increased PAC utilization, and a substantial financial impact. We expect a similar outcome when CMS removes total hip arthroplasty from the inpatient-only list.

Background Osteoarthritis is a mechanical abnormality characterized by chronic joint pain associated with degeneration of the articular cartilage, synovitis, and local inflammation, leading to loss of function and pain. A connection exists between the peripheral nervous system and inflammatory joint degeneration. The process by which inflammation is influenced by the nervous system is known as neuroinflammation. One of the neuropeptides involved in peripheral neuroinflammation is nociceptin, a peptide related to the opioid class of substances. Nociceptin has both pro- and anti-inflammatory effects. Some studies show that nociceptin can be measured in synovial fluid, while other studies have not been able to detect it. The presence of nociceptin in synovial fluid could imply a molecular role for the neuropeptide in the joint, both physiologically as well as pathophysiologically. The goal of this pilot study was to determine whether nociceptin was present in the synovial fluid of osteoarthritic knees. Methods Patients undergoing primary total knee arthroplasty were enrolled after Institutional Review Board approval was obtained. Synovial fluid was aspirated from patients’ operative knee joints and blood samples were obtained. A commercially available enzyme Immunoassay kit was used to test for nociceptin. A linear mixed-effects model was developed to account for the repeated measurements and baseline covariates. Least squares (adjusted) means were derived from the model to compare the sample types and to compare subgroups. Results Twenty patients were included in this study. Nociceptin was detected in the synovial fluid and plasma of all patients. The mean concentration (± standard deviation) of nociceptin in synovial fluid was 28.7 ± 18.2 pg/ml. The mean concentration of nociceptin in plasma was 45.2 ± 24.3 pg/ml pre-procedure, and 40.1 ± 20.6 pg/ml post-tourniquet deflation. The nociceptin concentration in synovial fluid was significantly lower than the nociceptin concentration in plasma, both pre-procedure and post-tourniquet deflation (p = 0.002 and p = 0.016 respectively). The nociceptin concentration in both plasma and synovial fluid was significantly lower in females versus males (p = 0.012). Conclusion We demonstrated that nociceptin is present in synovial fluid and plasma of patients undergoing total knee arthroplasty. This implies a potential role for nociceptin in modulating inflammation in osteoarthritis. Trial registration ClinicalTrials.gov, NCT02528916. Retrospectively registered on August 19, 2015

Background Total knee arthroplasty (TKA) is commonly performed with proprietary, manual instrumentation provided by the surgical implant manufacturer. Registry studies and meta-analysis, with few outliers, have consistently shown similar functional outcomes and implant survival after TKA regardless of implant manufacturer, implant design, or surgical technique. We hypothesized that process mapping could identify areas for improvement in TKA instrumentation. Methods Seventeen TKA implant systems from 10 companies representing over 90% of all TKAs performed in the United States were evaluated. Instrumentation required for femoral, tibial, and patellar preparation was compared. The number of steps including surgical technician assembly steps, instrument handoffs, and surgeon steps were tabulated based off application of a standardized surgical flow, adjusted for manufacturer-recommended steps during completion of a TKA operation. Results Cruciate-retaining (CR) knee instrumentation in studied systems required 158-225 discrete steps and posterior-stabilized (PS) knees required 181-230 steps. With the fewest steps for femoral, tibial, and patellar instrumentation, CR and PS knee systems could be improved to 145 and 163 steps, respectively. The Arthrex iBalance and the Biomet Vanguard Microplasty required fewest steps among CR systems; the OrthoDevelopment Balanced and the Corin Unity required fewest steps among PS systems. Conclusions Process mapping identified potential areas for improved instrumentation in all studied systems, suggesting the possibility to reduce operative steps broadly across the TKA industry. Patient outcomes were not evaluated by system. Future implant system design changes may do well to reduce unnecessary steps and instrumentation.

Background: Patients with severe hemophilia A and inhibitors are at risk of bleeding during invasive procedures. The standard of care for preventing perioperative bleeding has been replacement therapy with FVIII concentrates or for patients with high-titer inhibitors, bypassing agents. However, there is no consensus on the appropriate management of surgery in patients receiving the novel agent emicizumab. The aim of this study was to demonstrate a case of a patient on emicizumab undergoing major surgery with bypassing agents with preoperative use of the thrombin generation assay (TGA) and thromboelastography (TEG). Methods: We report a patient with hemophilia A with inhibitors who had undergone a total knee replacement while on emicizumab combined with a bypassing agent. We utilized TEG and TGA to determine which bypassing agent to choose as well as to inform about the ideal dose. Results: We elected to use recombinant FVIIa as a bypassing agent for the surgery based upon the TGA results. Conclusion: The TGA can be utilized to support decision-making in patients on emicizumab undergoing major surgery to both predict efficacy and potentially minimize the risk of thrombotic events.

Background Acute and acute hematogenous prosthetic joint infections (PJIs) are often treated with open debridement and polyethylene exchange (ODPE) in an effort to save the prosthesis, decrease morbidity, and reduce costs. However, failure of ODPE may compromise a subsequent 2-stage treatment. The purpose of this study is to identify patient factors that impact the success of ODPE for acute and acute hematogenous PJIs. Methods A retrospective review examined comorbidities, preoperative laboratory values, and patient history for patients with successful and failed ODPE treatment for acute perioperative or acute hematogenous periprosthetic hip or knee joint infections. Successful treatment was defined as retaining a well-fixed implant without the need for additional surgery for a minimum of 6-month follow-up with or without lifelong oral maintenance antibiotics. Results Fifty-three of 72 patients (73.6%) underwent successful ODPE. Of the 19 failures, 14 completed 2-stage revision with one subsequent known failure for recurrent infection. Patients with a Staphylococcus aureus infection were more likely to fail ODPE (48.3% vs 11.6%, P = .0012, odds ratio 7.1, 95% confidence interval 2.3-25.3). Patients with a preoperative hematocrit ≤32.1 were also more likely to fail ODPE (55% vs 16%, P = .0013, odds ratio 6.7, 95% confidence interval 2.2-22.4). When neither risk factor was present, 97.1% of PJIs were successfully treated with ODPE. Conclusion S aureus infection and preoperative hematocrit ≤32.1 are independent risk factors for ODPE failure. ODPE is a safe alternative to 2-stage revision in patients without preoperative anemia and without S aureus infection. Two-thirds of patients with a failed ODPE were successfully treated with a 2-stage reimplantation.

Background Centers for Medicare and Medicaid Services removed total knee arthroplasties (TKAs) from the Inpatient-Only list on January 1, 2018, which meant TKAs could be performed on a hospital outpatient basis. We sought to understand (1) what the financial implications have been for hospitals, (2) to what extent financial incentives have influenced the adoption of outpatient TKAs across hospitals, (3) whether adoption of outpatient TKAs has impacted the success of hospitals with managing post-acute care (PAC) spend, and (4) the financial implications to Medicare of the adoption of outpatient TKAs. Methods We used national patient-level Medicare fee-for-service Part A claims data (100% sample) from January 2018 through June 2019 to calculate the inpatient and outpatient TKA payment rate for each hospital, and the distribution in these payments across the country. We then ran case-level regressions to understand the factors associated with adoption of outpatient TKAs, and the drivers of PAC spend. Finally, we quantified the savings to Medicare. Results Hospitals on average received $3682 (30%) lower payment from Medicare for outpatient TKA cases, but this varied widely across hospitals. The difference in payment rates across hospitals was not statistically significantly related to their adoption rate of outpatient TKAs. PAC spend was higher for same-day discharges, but lower for cases that stayed at least 1 night. Based on the adoption rate of outpatient TKAs in Q2 2019, Medicare saved $355M on a run rate basis. Conclusion Hospitals have adopted outpatient TKAs independent of the financial impact. Medicare has benefited from lower PAC spend and lower payments to hospitals.

The continued presence of biofilm may be one cause of the high risk of failure observed with irrigation and debridement with component retention in acute periprosthetic joint infection (PJI). There is a poor understanding of the role of biofilm antibiotic tolerance in PJI. (1) Do increasing doses of cefazolin result in decreased viable biofilm mass on arthroplasty materials? (2) Is cefazolin resistance phenotypic or genotypic? (3) Is biofilm viability a function of biofilm depth after treatment with cefazolin? (4) Is the toxin-antitoxin system, yoeB expression, associated with antibiotic stress? Methicillin-sensitive Staphylococcus aureus biofilm was cultured on total knee arthroplasty (TKA) materials and exposed to increasing doses of cefazolin (control, 0.5, 1.0, 10.0, 100.0 μg/mL). Quantitative confocal microscopy and quantitative culture were used to measure viable biofilm cell density. To determine if cefazolin resistance was phenotypic or genotypic, we measured minimum inhibitory concentration (MIC) after exposure to different cefazolin concentrations; changes in MIC would suggest genotypic features, whereas unchanged MIC would suggest phenotypic behavior. Finally, quantitative reverse transcription-polymerase chain reaction was used to quantify expression of yoeB levels between biofilm and planktonic bacteria after exposure to 1 μg/mL cefazolin for 3 hours. Although live biofilm mass was reduced by exposure to cefazolin when compared with biofilm mass in controls (39.2 × 103 ± 26.4 × 103 pixels), where the level after 0.5 µg/mL exposure also showed reduced mass (20.3 × 103 ± 11.9 × 103 pixels), no further reduction was seen after higher doses (mass at 1.0 µg/mL: 5.0 × 103 pixels ± 1.1 × 103 pixels; at 10.0 µg/mL: 6.4 × 103 ± 9.6 × 103 pixels; at 100.0 µg/mL: 6.4 × 103 ± 3.9 × 103). At the highest concentration tested (100 µg/mL), residual viable biofilm was present on all three materials, and there were no differences in percent biofilm survival among cobalt-chromium (18.5% ± 15.1%), polymethylmethacrylate (22.8% ± 20.2%), and polyethylene (14.7% ± 10.4%). We found that tolerance was a phenotypic phenomenon, because increasing cefazolin exposure did not result in changes in MIC as compared with controls (MIC in controls: 0.13 ± 0.02; at 0.5 µg/mL: 0.13 ± 0.001, p = 0.96; at 1.0 µg/m: 0.14 ± 0.04, p = 0.95; at 10.0 µg/m: 0.11 ± 0.016, p = 0.47; at 100.0 µg/m: 0.94 ± 0.047, p = 0.47). Expression of yoeB after 1 µg/mL cefazolin for 3 hours in biofilm cells was greater in biofilm but not in planktonic cells (biofilm: 62.3-fold change, planktonic cells: −78.8-fold change, p < 0.001). Antibiotics are inadequate at complete removal of the biofilm from the surface of TKA materials. Results suggest that bacterial persisters are responsible for this phenotypic behavior allowing biofilm high tolerance to antibiotics. Antibiotic-tolerant biofilm suggests a mechanism behind the poor results in irrigation and debridement for acute TKA PJI.

Background Higher body mass index (BMI) has been associated with postoperative complications in total knee arthroplasty (TKA) and total hip arthroplasty (THA). However, the association of incremental increases of BMI and its effects on postoperative complications has not been well studied. We hypothesize that there is a BMI cutoff at which there is a significant increase of the risk of postoperative complications. Methods We studied the American College of Surgeons National Surgical Quality Improvement Program from 2006 to 2013. The final cohort included 77,785 primary TKA and 49,475 primary THA subjects, respectively. Patients were separated into 7 groups based on BMI (18.5-24.9 kg/m 2 , 25.0-29.9 kg/m 2 , 30.0-34.9 kg/m 2 , 35.0-39.9 kg/m 2 , 40.0-44.9 kg/m 2 , 45.0-49.9 kg/m 2 , and >50.0 kg/m 2 ). We analyzed data on five 30-day composite complication variables, including any complication, major complication, wound infection, systemic infection, and cardiac and/or pulmonary complication. Results The odds ratio for 4 (any complication, major complication, wound infection, and systemic infection) of 5 composite complications started to increase exponentially once BMI reached 45.0 kg/m 2 or higher in TKA. Similarly, the odds ratio in 3 (any complication, systemic infection, and wound infection) of 5 composite complications showed similar trends in THA patients. These findings were further confirmed with propensity score matching and entropy balancing. Conclusions Our study suggested that there was a positive correlation between BMI and incidences of 30-day postoperative complications in both TKA and THA. The odds of complications increased dramatically once BMI reached 45.0 kg/m 2 .

Background Patient-reported outcomes are essential to demonstrate the value of hip and knee arthroplasty, a common target for payment reforms. We compare patient-reported global and condition-specific outcomes after hip and knee arthroplasty based on hospital participation in Medicare’s bundled payment programs. Methods We performed a prospective observational study using the Comparative Effectiveness of Pulmonary Embolism Prevention after Hip and Knee Replacement trial. Differences in patient-reported outcomes through 6 months were compared between bundle and nonbundle hospitals using mixed-effects regression, controlling for baseline patient characteristics. Outcomes were the brief Knee Injury and Osteoarthritis Outcomes Score or the brief Hip Disability and Osteoarthritis Outcomes Score, the Patient-Reported Outcomes Measurement Information System Physical Health Score, and the Numeric Pain Rating Scale, measures of joint function, overall health, and pain, respectively. Results Relative to nonbundled hospitals, arthroplasty patients at bundled hospitals had slightly lower improvement in Knee Injury and Osteoarthritis Outcomes Score (−1.8 point relative difference at 6 months; 95% confidence interval −3.2 to −0.4; P = .011) and Hip Disability and Osteoarthritis Outcomes Score (−2.3 point relative difference at 6 months; 95% confidence interval −4.0 to −0.5; P = .010). However, these effects were small, and the proportions of patients who achieved a minimum clinically important difference were similar. Preoperative to postoperative change in the Patient-Reported Outcomes Measurement Information System Physical Health Score and Numeric Pain Rating Scale demonstrated a similar pattern of slightly worse outcomes at bundled hospitals with similar rates of achieving a minimum clinically important difference. Conclusions Patients receiving care at hospitals participating in Medicare’s bundled payment programs do not have meaningfully worse improvements in patient-reported measures of function, health, or pain after hip or knee arthroplasty.

Background U.S. health care is responding to significant regulation and meaningful incentives for higher quality care, patient safety, electronic documentation and data exchange. FDA’s Unique Device Identification (UDI) Rule, a relatively new regulation aligned with these goals, requires standard labeling of medical devices by manufacturers. This lays the foundation for UDI scanning and documentation in the electronic health record, expected to change the landscape of medical device identification and postmarket surveillance. Methods We developed national projections for time, cost and failure in implant identification prior to revision total hip and knee arthroplasty (THA/TKA) using American Association of Hip and Knee Surgeons 2012 membership survey data, Nationwide Inpatient Sample 2011 data and THA/TKA demand projection data. Results Our projections suggest that cumulative surgeon time spent identifying failed implants could reach 133,000 h in 2030, representing opportunity to perform over 500,000 15 min established patient office visits. Staff time could reach 220,000 h with a cost of $3.3 m. Failed implants that cannot be identified may be greater than 50,000 preoperatively and 25,000 intraoperatively in 2030. Conclusion Study projections indicate significant time, cost and inability to identify failed implants, supporting need for improvement of implant documentation. FDA’s UDI Rule sets the foundation for UDI scanning and documentation in the electronic health record, a process poised to serve as the standard system for device documentation.

Introduction: Understanding and planning for the factors that impact supply cost and unplanned readmission risk for total joint arthroplasty (TJA) patients is helpful for hospitals at financial risk under bundled payments. Readmission and operating room supply costs are two of the biggest expenses. Methods: Logistic and linear regressions are used to measure the impacts of TJA patient attributes on readmission risk and supply costs, respectively. Results: Patients’ health market segment and the number/type of comorbidity impacts 30/90-day readmission rates. Surgeon implant preference and type of surgery impact supply costs. Discharge location and two of the five health market segments increase the odds of 30-day readmission. Arrhythmia and lymphoma are the primary comorbidities that impact the odds of readmission at 90 days. Conclusions: Preoperatively identifying TJA patients likely to have large supply costs and higher readmission risk allows hospitals to invest in low-cost interventions to reduce risk and improve healthcare value.

Treatment in periprosthetic joint infection (PJI) remains challenging. The failure rate of two-stage revision and irrigation and debridement with component retention in PJI suggests that biofilm cells have a high tolerance to antibiotic chemotherapy. Previous work has demonstrated that biofilm cells have high antibiotic tolerance in vitro, but there is little clinical evidence to support these observations. The aim of this study was to determine if retrieved antibiotic spacers from two-stage revision total knee arthroplasty for PJI have evidence of remaining viable bacteria. Antibiotic poly (methyl methacrylate) (PMMA) spacers from two-stage revision total knee arthroplasty for PJI were prospectively collected and analyzed for bacterial 16s rRNA using polymerase chain reaction (PCR), reverse transcription (RT)-PCR, quantitative RT-PCR (qRT-PCR), and single genome analysis (SGA). PCR and RT-PCR identified bacterial species on 53.8% (7/13) of these samples. When initial culture negative cases are excluded, 68% (6/9) samples were identified with bacterial species. A more rigorous qRT-PCR analysis showed a strong positive signal for bacterial contamination in 30.7% (4/13) of cases. These patients did not show any clinical evidence of PJI recurrence after 15 months of follow-up. Because the half-life of bacterial rRNA is approximately a few days, the identification of bacteria rRNA on antibiotic PMMA spacers suggests that viable bacteria were present after conclusion of antibiotic therapy. This study provides evidence for the high tolerance of biofilm cells to antibiotics in vivo and the important role of bacterial persisters in PJI. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:452-458, 2018.

FDA's Unique Device Identification (UDI) Rule will mandate manufacturers to assign unique identifiers to their marketed devices. UDI use is expected to improve implant documentation and identification. A 2012 American Association of Hip and Knee Surgeons membership survey explored revision total hip and knee arthroplasty implant identification processes. 87% of surgeons reported regularly using at least 3 methods to identify failed implants pre-operatively. Median surgeon identification time was 20 min; median staff time was 30 min. 10% of implants could not be identified pre-operatively. 2% could not be identified intra-operatively. UDI in TJA registry and UDI in EMR were indicated practices to best support implant identification and save time. FDA's UDI rule sets the foundation for UDI use in patient care settings as standard practice for implant documentation.

Contingency analysis is a critical activity in the context of the power infrastructure because it provides a guide for resiliency and enables the grid to continue operating even in the case of failure. In this paper, we augment this concept by introducing SOCCA, a cyber-physical security evaluation technique to plan not only for accidental contingencies but also for malicious compromises. SOCCA presents a new unified formalism to model the cyber-physical system including interconnections among cyber and physical components. The cyber-physical contingency ranking technique employed by SOCCA assesses the potential impacts of events. Contingencies are ranked according to their impact as well as attack complexity. The results are valuable in both cyber and physical domains. From a physical perspective, SOCCA scores power system contingencies based on cyber network configuration, whereas from a cyber perspective, control network vulnerabilities are ranked according to the underlying power system topology.

Utilities need to understand and consider the interconnectedness of their electrical system and its supporting cyber infrastructure to maintain system reliability in the face of cyber adversaries. This paper makes two contributions to modeling cyber-physical dependencies within the electrical power sector. First, the paper defines a Common Format using the Cyber-Physical Topology Language (CPTL) to inventory, analyze, and exchange cyber-physical model information. Second, the paper provides an 8-substation cyber-physical reference model. The impact of this work is to enable efficient information exchange of cyber-physical topologies within and among the industry as well as the research community. The reference model and framework will benefit the research community by providing a way to compare analyses on electrical power systems that account for problems within cyber control networks.

This article was updated on May 4, 2016, because of a previous error. On page 689, under the “DELAY TKA” heading, the text had previously read “Moderate evidence supports that a 5-month delay to total knee arthroplasty (TKA) does not worsen outcomes.” The text now reads “Moderate evidence supports that an 8-month delay to total knee arthroplasty (TKA) does not worsen outcomes.” An erratum has been published: J Bone Joint Surg Am. 2016 June 15;98(12):e53. The AAOS Evidence-Based Guideline on Surgical Management of Osteoarthritis of the Knee includes both diagnosis and treatment. This clinical practice guideline has been endorsed by the Arthroscopy Association of North America (AANA) and the Society of Military Orthopaedic Surgeons (SOMOS). This brief summary of the AAOS Clinical Practice Guideline contains a list of the recommendations and the rating of strength based on the quality of the supporting evidence. Discussion of how each recommendation was developed and the complete evidence report are contained in the full guideline at http://www.aaos.org/Quality/Clinical\_Practice\_Guidelines/Clinical\_Practice\_Guidelines/. ### BMI AS A RISK FACTOR Strong evidence supports that obese patients have less improvement in outcomes with total knee arthroplasty (TKA). Strength of Recommendation: Strong ★★★★ ### DIABETES AS A RISK FACTOR Moderate evidence supports that patients with diabetes are at higher risk for complications with total knee arthroplasty (TKA). Strength of Recommendation: Moderate ★★★☆ ### CHRONIC PAIN AS A RISK FACTOR Moderate evidence supports that patients with select chronic pain conditions have less improvement in patient reported outcomes with TKA. Strength of Recommendation: Moderate ★★★☆ ### DEPRESSION/ANXIETY AS A RISK FACTOR Limited evidence supports that patients with depression and/or anxiety symptoms have less improvement in patient reported outcomes with total knee arthroplasty (TKA). Strength of Recommendation: Limited ★★☆☆ ### CIRRHOSIS/HEPATITIS C AS A RISK FACTOR Limited evidence supports that patients with cirrhosis …

The outcomes of 18 primary or revision total hip (THA) and knee arthroplasties (TKA) in 9 patients with cardiac transplants were reviewed. Primary total joint arthroplasties were performed for osteonecrosis (5 hips) or osteoarthritis (5 hips, 4 knees). There were no infections in any of these patients. Final Harris Hip Scores were 71.8 for patients with osteonecrosis and 88.6 for osteoarthritis. Eight of 10 hips were pain-free at final follow-up. Two of the 10 primary THAs required late revision at 7 and 10 years after the index arthroplasty. One patient (2 hips and 1 knee) had chronic bilateral lower extremity pain. Total knee arthroplasty range of motion averaged from 7.5° to 118°. Average final Knee Society function score was 79, and objective score was 88. One of 4 patients with primary TKA required a manipulation under anesthesia. No reoperations were required in this group. Overall, patients with heart transplantations on immunosuppression had generally good pain relief after THA and TKA. There were no infections in this small cohort; however, there were many complications.

This paper presents a method for determining the double outage contingencies that threaten the system without solving the full contingency set. Two methods for contingency screening with complementary properties are presented. The results of the algorithms are compared to the full double outage contingency analysis results for a large North American case. The results show that the screening algorithms are able to detect nearly all of the contingencies that will result in violations, while requiring only a small fraction of the contingencies to be solved.

Case We describe a case of septic hip arthritis and enterocutaneous fistula formation caused by the seeding of a hip joint during hip arthroscopy performed in the setting of a psoas abscess. Treatment consisted of multiple debridements and femoral head resection with subsequent total hip arthroplasty. Conclusions This case highlights the importance of a thorough history, physical examination, and assessment of available imaging before proceeding to surgery, even when the procedure is one considered to have minimal risks, such as arthroscopy.

Fox, James F., Charles M. Davis, and Darren K. Martin, 2010. Sediment Source Assessment in a Lowland Watershed Using Nitrogen Stable Isotopes. Journal of the American Water Resources Association (JAWRA) 46(6):1192–1204. DOI: 10.1111/j.1752-1688.2010.00485.x Abstract: Sediment sources and transported sediments were sampled in a lowland watershed with pronounced fine sediment storage in the streambed. Sediments were analyzed for carbon and nitrogen content and stable nitrogen isotopic composition. Analysis of the data shows that temporarily stored streambed sediments dominate the sediment load during moderate- and low-flow hydrologic events. Modeling of sediment transport and nitrogen elemental and isotopic mass balance was performed for the watershed for a 12-month time period using a continuous, conceptual-based model. The model results show that during moderate- and low-flow hydrologic events, the streambed is slowly downcutting. During very high-flow hydrologic events, deposition is pronounced in the streambed and sediment is replenished to the bed. Nitrogen model results show that elemental and isotopic nitrogen of streambed sediments vary substantially over the simulation period. In this manner, the streambed in a lowland watershed functions as a temporary storage zone that, in turn, can impact the nitrogen elemental and isotopic signature of sediments. The variation could significantly impact estimates of sediment provenance using nitrogen tracer-based methods. Future work should consider both hydrologic and biogeochemical control on the nitrogen isotopic signature of sediments in small lowland watersheds and streams where a significant portion of deposited fines are temporarily stored.

To evaluate the effects of the economic downturn on adult reconstruction surgery in the United States, a survey of the American Association of Hip and Knee Surgeons (AAHKS) membership was conducted. The survey evaluated surgical and patient volume, practice type, hospital relationship, total joint arthroplasty cost control, employee staffing, potential impact of Medicare reimbursement decreases, attitudes toward health care reform options and retirement planning. A surgical volume decrease was reported by 30.4%. An outpatient visit decrease was reported by 29.3%. A mean loss of 29.9% of retirement savings was reported. The planned retirement age increased to 65.3 years from 64.05 years. If Medicare surgeon reimbursement were to decrease up to 20%, 49% to 57% of AAHKS surgeons would be unable to provide care for Medicare patients, resulting in an unmet need of 92,650 to 160,818 total joint arthroplasty procedures among AAHKS surgeons alone. Decreases in funding for surgeons and inadequate support for subspecialty training will likely impact access and quality for Americans seeking adult reconstruction surgery.

BackgroundThoracic endoluminal aortic aneurysm repair (TEVAR) is associated with improved outcomes compared with open thoracic aortic aneurysm repair. This study was designed to better characterize TEVAR outcomes in a large population, and to determine if outcomes are independently influenced by patient ethnicity and insurance status.MethodsUsing the Nationwide Inpatient Sample (NIS) database, we selected patients who underwent TEVAR between 2001 and 2005. Ethnicity and insurance type were independently evaluated against the outcome variables of mortality and postoperative complications. Age, gender, hospital region, hospital location, hospital size, and comorbidities were controlled as cofounders.ResultsBetween 2001 and 2005, 875 patients underwent TEVAR. There was a significantly greater proportion of Caucasians (n = 650) compared with African Americans (n = 104) or Hispanics (n = 49). Patients had a male preponderance, and most procedures were elective. The overall mortality was 13.3% (n = 117), and spinal cord ischemia was 0.8% (n = 7), with no differences between patients of varied ethnicity or payer status. Significant differences were noted among the races including gender (P = .003), income (P < .0001), hospital region (P < .001), hospital bed size (P = .013), and insurance type (P < .001). Significant variations in demographics characteristics were also present between patients with different insurance classifications including gender (P < .001), surgery type (P = .009), income (P = .003), race (P < .0001), and comorbidity index (P < .0001). After adjustment for cofounders and multiple comparisons, there were no differences in rates of complications among patients with varying race or insurance status.ConclusionsMortality after TEVAR remains high in the US, although this may be associated with its early introduction during the study period. Nonetheless, the incidence of spinal cord ischemia is very low. Ethnicity and insurance type do not appear to influence TEVAR outcomes.

Sediment fingerprinting has been developed by researchers over the past three decades for watershed sediment transport research. Sediment fingerprinting is a method to allocate sediment nonpoint source pollutants in a watershed through the use of natural tracer technology with a combination of field data collection, laboratory analyses of sediments, and statistical modeling techniques. The method offers a valuable tool for total maximum daily load assessment to aid in developing efficient remediation strategies for pollution in watersheds. We review the methodological steps of sediment fingerprinting including classification of sediment sources in a watershed, identification of unique tracers for each sediment source, representation of sediment sources and sinks using field sampling, accounting for sediment and tracer fate during transport from source to sink, and utilization of an unmixing model to allocate sediment sources. This review places additional emphasis upon tracers used to discriminate sediment sources during past studies performed on different continents and across different physiogeographic regions. Review and analysis of tracer dependence upon watershed variables provides an additional resource for tracer selection to the community. Finally, future improvements needed for sediment fingerprinting are discussed in order to practically apply the technology for sediment nonpoint source pollution allocation within the context of total maximum daily load assessments.

Measurements of the distribution of carbon and nitrogen isotopes in soils are needed due to their potential to improve our understanding of soil CO 2 emissions and sequestration under varying climatic conditions and land management technologies. Organic carbon and nitrogen isotopic and elemental composition was measured in baseline forest soils as well as in anthropogenically and intermittently flooded soils in the southern Appalachian Mountains. For the undisturbed forest soils, the consistent relationship between elemental and isotopic composition in the soil column, across soil organic matter pools, was supportive of the hypothesis that isotopic signature is reflective of microbial induced carbon turnover and nitrogen decomposition. A climatologic analysis suggested that isotopic indicators of soil organic matter turnover were influenced by mean annual temperature at our study sites, as well as in 10 other regional and global soil carbon and nitrogen isotopic studies. Intermittently flooded soils showed carbon and nitrogen distributions that reflected successive high magnitude events where sediments were deposited upon a developing forest floor. Measurements from soils disturbed by mining, agriculture, and recreation suggest the potential for using carbon and nitrogen isotopes to indicate the degree of soil organic matter turnover induced by different land management scenarios.

Objective May-Thurner syndrome is characterized by left common iliac obstruction secondary to compression of the left iliac vein by the right common iliac artery against the fifth-lumbar vertebra. This anatomic variant results in an increased incidence of left-sided deep venous thrombosis (DVT). Furthermore, while a preponderance of left-sided DVT has been demonstrated in women during pregnancy and oral contraceptive use, patients are not typically screened for this condition after developing a left-sided DVT. As anticoagulation alone is ineffective for DVT treatment in the setting of May-Thurner anatomy, more aggressive treatment is warranted. Failure to diagnosis this condition predisposes these women to the unnecessary risks of recurrent DVT and post-thrombotic syndrome. Methods We present the occurrence of 7 adolescent patients with previously undiagnosed May-Thurner syndrome who presented with DVT after the initiation of oral contraceptive steroids (OCP) use. All 7 patients elected to proceed with mechanical thrombolysis/catheter based thrombolysis followed by endovascular stenting and were postoperatively treated with 6 months of warfarin. Results Mean patient age was 18.3 ± 3.3 years (range, 16-24 years). Mean time to presentation after initiation of OCP was 5 weeks (range, 2-10 weeks). Mean time to intervention was 16.8 days (range, 10-24 days). All patients were treated with mechanical thrombectomy. Our rate of intraoperative clot resolution was 100%. All 7 patients were treated with self expanding nitinol stents after angioplasty of the iliac vein stenosis with resolution of the stenotic segment. Primary stent patency is 100% (7/7). Mean follow-up time is 13 ± 13.84 months (range, 6-42 months). There have been no long-term complications related to surgical treatment or anticoagulation. All 7 patients have experienced resolution of left leg swelling and pain and have no evidence of post-thrombotic syndrome or DVT recurrence to date. Conclusions Women on OCPs presenting with left-sided iliofemoral DVT should be screened for hypercoagulable disorders and underlying May-Thurner anatomy. Treatment of May-Thurner syndrome should include thrombolysis/thrombectomy and anticoagulation for current DVT in addition to angioplasty and stenting of the underlying obstruction.

ObjectiveThis study analyzed device-specific aneurysm sac morphology after endovascular aneurysm repair (EVAR) with low-permeability devices.MethodsBetween September 2004 and May 2006, 122 patients were treated with EVAR. Three different devices were implanted: 47 Zenith (Cook, Indianapolis, Ind), 46 AneuRx (Medtronic, Santa Rosa, Calif) with Resilient Dacron Graft Material, and 29 Excluder (W. L. Gore & Associates, Flagstaff, Ariz) with low-porosity polytetrafluoroethylene (PTFE). Patients were followed up at 1, 6, and 12 months and then biannually with computed tomography (CT) angiography. Standard axial two-dimensional CT measurements were obtained and compared with preoperative imaging. The preoperative scan served as a baseline, and the minor axis diameter, measured at the largest axial cut of the abdominal aortic aneurysm, was compared with the same measurement at follow-up.ResultsPatient age, sex, and preoperative aneurysm morphology were similar among groups. Patients receiving the Zenith endograft had a significantly larger neck diameter; however, there was no difference in the neck length between groups. The rate of type II endoleaks was similar for the Zenith (17%), AneuRx (17%), and Excluder (14%). At 1, 6, 12, and 18 months, all three grafts were associated with sac shrinkage. The resulting decreases in mean aneurysm size at 18 months and corresponding shrinkage were Zenith, 11%, 6.4 ± 1.8 mm; AneuRx, 18.9%, 12.7 ± 2.7 mm; and the Excluder, 5.5%, 3.3 ± 0.9 (P < .05). The sac size in the 19 patients with a type II endoleak decreased 8.06% compared with a 15.43% decrease in sac size in patients without endoleak at 6 months. No significant sac expansion ≥5 mm has been observed among any of the groups to date.ConclusionsSac regression with all devices appears to have been favorably influenced by the new generation of graft materials and is improved compared with published reports of older generation graft materials for the AneuRx and Excluder. However, there is a trend toward greater sac regression with devices using Dacron vs PTFE. The relationship of aneurysm morphology and long-term effects on aortic stent grafts is yet to be determined.

Background: Hyponatremia is common among orthopaedic patients and is associated with adverse clinical outcomes. We examined the prevalence, timing, causes, and outcomes of hyponatremia in adult hospitalized orthopaedic surgery patients. Methods: We evaluated the medical records of 1067 consecutive orthopaedic surgery patients admitted to a tertiary academic institution. The medical records were reviewed to investigate hyponatremia (serum sodium

Background: Bipolar hip arthroplasty has been advocated by some as an alternative to total hip arthroplasty for the treatment of degenerative arthritis of the hip. We sought to assess the results of this procedure at our institution after a minimum duration of follow-up of ten years. Methods: We retrospectively reviewed a consecutive series of 152 patients (173 hips) who underwent primary bipolar hemiarthroplasty for the treatment of symptomatic degenerative arthritis of the hip with a cementless femoral component between 1983 and 1987. Of the original cohort of 152 patients, ninety-two patients (104 hips) were available for clinical and radiographic review at a mean of 12.2 years postoperatively. At the time of the latest follow-up, self-administered Harris hip questionnaires were used to assess pain, mobility, activity level, and overall satisfaction with the procedure. Biplanar hip radiographs were made to evaluate bipolar shell migration, osteolysis, and femoral stem fixation. Results: At the time of the latest follow-up, nineteen patients (nineteen hips) had undergone revision to total hip arthroplasty because of mechanical failure, and three patients (three hips) were awaiting revision because of symptomatic radiographic mechanical failure. Twelve acetabular revisions were performed or scheduled for the treatment of pelvic osteolysis or protrusio acetabuli secondary to component migration. Acetabular reconstruction required bone-grafting, an oversized shell, and/or a pelvic reconstruction ring. The overall rate of mechanical failure was 21.2% (twenty-two of 104 hips), with 91% (twenty) of the twenty-two failures involving the acetabular component. Reaming of the acetabulum at the time of the index arthroplasty was associated with a 6.4-fold greater risk of revision. The rate of implant survival, with revision because of mechanical failure as the end point, was 94.2% for femoral components and 80.8% for acetabular components at a mean of 12.2 years. Of the remaining sixty-nine patients (eighty-one hips) in whom the original prosthesis was retained, seventeeen patients (24.6%) rated the pain as moderate to severe. Nearly 30% of patients with an intact prosthesis required analgesics on a regular basis. Radiographs were available for fifty-eight hips (including all of the hips with moderate to severe pain) after a minimum duration of follow-up of ten years; twenty-eight of these fifty-eight hips had radiographic evidence of acetabular component migration. Conclusions: This bipolar cup, when used for hemiarthroplasty in patients with symptomatic arthritis of the hip, was associated with unacceptably high rates of pain, migration, osteolysis, and the need for revision to total hip arthroplasty, especially when the acetabulum had been reamed. To the extent that these findings can be generalized to similar implant designs with conventional polyethylene, we do not recommend bipolar hemiarthroplasty as the primary operative treatment for degenerative arthritis of the hip. Level of Evidence: Therapeutic Level IV. See Instructions to Authors for a complete description of levels of evidence.

Management of periprosthetic fractures around the knee is often difficult because of poor bone quality, comminution, and constraints imposed by the existing prosthesis. Locked condylar plates may provide more reliable fixation for these fractures than traditional methods of fixation. Eleven patients with periprosthetic fractures around the knee were treated with open reduction and internal fixation using a locked condylar plate. All 9 acute fractures and 1 of 2 periprosthetic nonunions healed at an average of 21 weeks, and no patient required additional surgery. Nine fractures healed in anatomical alignment, whereas 1 healed in 5 degrees valgus. The remaining periprosthetic nonunion developed a persistent nonunion with subsequent hardware failure. The average range of motion was 4 degrees to 92 degrees . Locked plating systems are highly effective for the management of complex periprosthetic fractures around the knee. They result in reliable fracture healing and permit early motion in complex fractures.

Background: The long-term results of revision of failed primary cemented femoral components with use of cement have been reported, but there is little information about the results of revision of failed uncemented femoral components with use of cement. The purpose of the present study was to examine the minimum five-year results for patients in whom a failed uncemented primary femoral component was revised with use of modern cementing techniques. Methods: Forty-eight consecutive hips (forty-seven patients) in which a failed primary uncemented femoral component was revised with use of cement at one institution from 1985 to 1992 were followed prospectively and reviewed retrospectively. The mean age of the patients at the time of revision was sixty-seven years. Only seven revisions were performed with a long-stem femoral component. The postoperative cement mantle was classified, according to the system of Mulroy and Harris, as grade A in four hips, grade B in twenty-five, grade C1 in seven, grade C2 in twelve, and grade D in none. Results: Eleven femoral components were removed or revised because of aseptic loosening (ten) or deep infection (one). An additional four unrevised femoral components had evidence of probable or definite loosening at the time of the final radiographic follow-up. Thus, fourteen (29%) of the forty-eight femoral implants demonstrated aseptic loosening during the study period. Five of the twenty-nine hips in which the postoperative cement mantle was classified as grade A or B had mechanical failure at the time of the final follow-up, compared with nine of the nineteen hips in which the postoperative cement mantle was classified as grade C1 or C2 (p < 0.05). Among the hips with surviving prostheses, 79% had had moderate or severe pain preoperatively whereas 25% had moderate or severe pain at the time of the final follow-up. The six-year rate of survival of the femoral component was 72% with revision for aseptic loosening as the end point and 67% with mechanical failure (revision for aseptic loosening or radiographic loosening) as the end point. Conclusions: While revision of a failed uncemented femoral implant with use of cement provided pain relief and improved function for most patients, the rate of loosening at the time of intermediate-term follow-up was higher than that commonly reported after revision of failed cemented implants with use of cement and also was higher than that commonly reported after revision with use of uncemented extensively porous-coated implants. Bone removal at the time of the initial implantation of the stem and bone loss due to subsequent failure of the uncemented implant often left little intramedullary cancellous bone, which may explain the high rate of loosening observed in the first decade after revision in this series. Level of Evidence: Therapeutic study, Level IV (case series [no, or historical, control group]). See Instructions to Authors for a complete description of levels of evidence.

We examined the concurrent validity properties of the Facial Discrimination Task (FDT), an instrument for the assessment of facial emotion recognition by comparing it with the widely used Pictures of Facial Affect (PFA). In Study 1, 100 adults with heterogeneous psychiatric diagnoses were administered items of the FDT Emotion Task, the FDT Age Task, and PFA. In Study 2, 25 normally developing preschool children were instructed to label happy, sad, or neutral facial expressions from the FDT and the PFA. Despite methodological differences between the two studies, very similar and high correlations were found between the FDT and the PFA overall correct scores (r = .79 and r = .77, respectively). The data suggest that the FDT and the PFA measure similar competencies in preschoolers and in adults with psychiatric disorders. This finding is important because it establishes the concurrent validity of the FDT in child and adult populations.

The purpose of this study was to evaluate the economic attributes of private practice adult reconstruction (AR) offices. 458 AAHKS surgeons responded; 65% were in private practice (fee-for-service, non-salaried, non-employed AR surgeons). 54% had considered hospital employment in the past two years. The average group employs 13.4 orthopedic surgeons (3.4 AR), and 105 other employees. The average total budget is $12.5 million per year with $4 million in salaries, and $238,000 in tax revenue generated. Co-management joint ventures are a better model than hospital employment for aligning AR surgeons and hospitals and realizing the cost effectiveness and quality improvement goals of PPACA and AARA while preserving the economic impact of AR private practice.

In acute periprosthetic infection, irrigation and debridement with component retention has a high failure rate in some studies. We hypothesize that pulse lavage irrigation is ineffective at removing biofilm from total knee arthroplasty (TKA) components. Staphylococcus aureus biofilm mass and location was directly visualized on arthroplasty materials with a photon collection camera and laser scanning confocal microscopy. There was a substantial reduction in biofilm signal intensity, but the reduction was less than a ten-fold decrease. This suggests that irrigation needs to be further improved for the removal of biofilm mass below the necessary bioburden level to prevent recurrence of acute infection in total knee arthroplasty.

Background: Hip fractures are common in the elderly, and patients with hip fractures frequently have comorbid illnesses. Little is known about the relationship between comorbid illness and hospital costs or length of stay following the treatment of hip fracture in the United States. We hypothesized that specific individual comorbid illnesses and multiple comorbid illnesses would be directly related to the hospitalization costs and the length of stay for older patients following hip fracture. Methods: With use of discharge data from the 2007 Nationwide Inpatient Sample, 32,440 patients who were fifty-five years or older with an isolated, closed hip fracture were identified. Using generalized linear models, we estimated the impact of comorbidities on hospitalization costs and length of stay, controlling for patient, hospital, and procedure characteristics. Results: Hypertension, deficiency anemias, and fluid and electrolyte disorders were the most common comorbidities. The patients had a mean of three comorbidities. Only 4.9% of patients presented without comorbidities. The average estimated cost in our reference patient was $13,805. The comorbidity with the largest increased hospitalization cost was weight loss or malnutrition, followed by pulmonary circulation disorders. Most other comorbidities significantly increased the cost of hospitalization. Compared with internal fixation of the hip fracture, hip arthroplasty increased hospitalization costs significantly. Conclusions: Comorbidities significantly affect the cost of hospitalization and length of stay following hip fracture in older Americans, even while controlling for other variables. Level of Evidence: Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Low vitamin D levels are common in psychiatric patients, but a need for vitamin D supplementation in these individuals remains controversial. Low vitamin D levels are reportedly associated with high prevalence of cardiometabolic risk factors, and both are common in psychiatric patients, but the relationship between diagnosis and severity of illness and cardiometabolic risk status and the effect of vitamin D treatment on them is not known. We studied these relationships and effect of vitamin D(3) treatment on them in 290 long-term psychiatric inpatients.All patients admitted to the hospital during April 2009-March 2010 who agreed to 25-hydroxyvitamin-D testing were included. Serum 25-hydroxyvitamin D level, Brief Psychiatric Rating Scale (BPRS) score, body mass index, blood pressure, and fasting levels of blood glucose, triglycerides, high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C) were measured at baseline, and changes after vitamin D(3) treatment for up to 12 months were observed. For the purposes of this study, 25-hydroxyvitamin-D levels32 ng/mL were considered as "low";20 ng/mL, as "insufficient"; and12 ng/mL, as "deficient."A serum 25-hydroxyvitamin-D level32 ng/mL was found in 90.0% of patients, and a level20 ng/mL was found in 48.6% of patients. A BPRS score36 was present in 56.0% of patients; obesity, in 75.7%; hypertension, in 44.8%; low HDL-C, in 43.6%; high triglycerides, in 31.2%; high LDL-C, in 17.8%; and increased glucose, in 14.6%. Serum 25-hydroxyvitamin-D levels correlated poorly with BPRS score and the other variables listed above (R, -0.02 to -0.22). After vitamin D(3) treatment, 25-hydroxyvitamin-D level increased to ≥ 20 ng/mL in all patients and ≥ 32 ng/mL in 85% of patients, but despite124% increase in mean 25-hydroxyvitamin-D level, mean improvement in other variables was12%.Nearly half of our patients had vitamin D levels20 ng/mL, putting them at risk for poor bone health and requiring vitamin D supplementation. Cardiometabolic risk factors were also highly prevalent, but correlated poorly with vitamin D levels in their severity. Increasing vitamin D levels to ≥ 32 ng/mL was not associated with improvement in BPRS score or any cardiometabolic risk factor, emphasizing that intensification of therapeutic measures other than vitamin D supplementation is required.

A 2008 survey of American Association of Hip and Knee Surgeons membership explored current venous thromboembolism (VTE) protocols for lower-extremity total joint surgery. Fifty-three percent reported a change in VTE-related practices in the last 5 years. More than 70% reported that their primary hospital now mandates VTE prophylaxis. Although 74% of their primary hospitals recognized the American College of Chest Physicians guidelines, 68% of surgeons felt the American Academy of Orthopaedic Surgeons guidelines were more relevant to their practice. Respondents believe low molecular weight heparin to be the most efficacious but aspirin to be the easiest to use and has the lowest risks of bleeding and wound drainage. Warfarin was the most used in hospital prophylaxis, and 90% of respondents targeted an international normalized ratio of 1.6 to 2.5. Practice patterns continue to evolve, and there remains no consensus on specific treatment protocols or preferences.

Phasor measurement units (PMUs) are beginning to be deployed widely in the power system, which gives system controllers the ability to directly measure phase angles. However, at present PMUs are only deployed at a small percentage of buses. This presents a challenge: how to get useful information from the small number of data points. This paper discusses work that has been done on visualizing the new data provided by PMUs. The paper begins by introducing the problems associated with visualizing PMU data in a wide area sense. It continues by discussing the application of equivalent circuit theory to arrive at equivalent injections. Next, difference contours are introduced as a way to alert operators to important changes without a cluttered display. Then, these ideas are applied to a large example system. Finally, conclusions and future work are discussed.