Perioperative Management of Traditional and Direct Oral Anticoagulants in Hip Fracture Patients.

Hip fractures are an increasingly common injury in the senior population and almost always require surgical fixation or prosthetic replacement. These surgeries, according to the American Academy of Orthopaedic Surgeons, are considered high-risk for bleeding, especially in a population fraught with comorbidities and often presenting on anticoagulation medications. Direct oral anticoagulants represent a class of drugs that have been becoming more popular in use in this population, with many benefits over the historically used Warfarin. There are recommendations for preoperative discontinuation and postoperative resumption of these medications, which can be more readily managed for elective surgeries. However, there is a paucity of literature detailing best practice guidelines for the perioperative management of direct oral anticoagulants when a patient presents with a hip fracture. This review article summary of the periprocedural management of DOACs for hip surgery was developed by examining the American College of Chest Physicians evidence-based clinical practice guidelines, Perioperative Guidelines on Antiplatelet and Anticoagulant Agents written by anesthesiologists, various retrospective studies, and drug labels for pharmacokinetic data. These recommendations should be used as a guideline, along with the collaboration of multidisciplinary hospital teams during inpatient admission, to manage these complex patients.

Are extra locking bolts or fibular plating more important in extreme nailing of distal tibia fractures? A cadaveric biomechanical analysis.

OBJECTIVES: In far-distal extra-articular tibia fracture "extreme" nailing, debate surrounds the relative biomechanical performance of plating the fibula compared with extra distal interlocks. This study aimed to evaluate several constructs for extreme nailing including one interlock (one medial-lateral interlock), one interlock + plate (one medial-lateral interlock with lateral fibula compression plating), and two interlocks (one medial-lateral interlock and one anterior-posterior interlock). METHODS: Fifteen pairs of fresh cadaver legs were instrumented with a tibial nail to the physeal scar. A 1 cm segment of bone was resected from the distal tibia 3.5 cm from the joint and an oblique osteotomy was made in the distal fibula. We loaded specimens with three different distal fixation constructs (one interlock, one interlock + plate, and two interlocks) through 10,000 cycles form 100N-700 N of axial loading. Load to failure (Newtons), angulation and displacement were also measured. RESULTS: Mean load to failure was 2092 N (one interlock), 1917 N (one interlock + plate), and 2545 N (two interlocks). Linear mixed effects modeling demonstrated that two interlocks had a load to failure 578 N higher than one interlock alone (95 % CI, 74N-1082 N; P = 0.02), but demonstrated no significant difference between one interlock and one interlock + plate. No statistically significant difference in rates or timing of displacement >2 mm or angulation >10° were demonstrated. CONCLUSIONS: When nailing far-distal extra-articular tibia and fibula fractures, adding a second interlock provides more stability than adding a fibular plate. Distal fibula plating may have minimal biomechanical effect in extreme nailing.

Increasing Value in Subspecialty Training: A Comparison of Variation in Surgical Complications for Pediatric Versus Other Fellowship-trained American Board of Orthopaedic Surgery Candidates in the Treatment of Supracondylar Fractures.

INTRODUCTION: The effect of orthopaedic fellowship subspecialization on surgical complications for patients with supracondylar fracture is unknown. This study seeks to compare the effect of subspecialty training on supracondylar fracture complications. METHODS: The American Board of Orthopaedic Surgery Part II Examination Case List database was reviewed for all supracondylar fractures from 1999 to 2016. Procedures were divided by fellowship subspecialty (trauma, pediatric, or other) and case volume and assessed by surgeon-reported surgical complications. Predictive factors of complications were analyzed using a binary multivariate logistic regression. RESULTS: Of 10,961 supracondylar fractures identified, 53.47% were done by pediatric fellowship-trained surgeons. Pediatric-trained surgeons had fewer surgical complications compared with their trauma or other trained peers (4.54%, 5.67%, and 6.24%; P = 0.001). Treatment by pediatric-trained surgeons reduced surgical complications (OR = 0.79, 95% CI: 0.66 to 0.94; P = 0.010), whereas increased case volume (31+ cases) showed no significant effect (OR = 0.79, 95% CI: 0.62 to 1.02; P = 0.068). Patient sex, age, and year of procedure did not affect complication rates, while those treated in the Southeast region of the United States and those with a complex fracture type were at increased odds. DISCUSSION: Treatment of supracondylar fractures by pediatric-trained surgeons demonstrates reduced surgeon-reported complications compared with their other fellowship-trained counterparts, whereas case volume does not. This suggests the value of fellowship training beyond pertinent surgical caseload among pediatric-trained surgeons and may lie in targeted education efforts.

Comparing Outcomes in Cemented and Press-Fit Hemiarthroplasty.

INTRODUCTION: Arthroplasty has become the standard of care for displaced femoral neck fractures in the geriatric cohort. However, details regarding optimal implant design and fixation strategy continue to be debated. We sought to determine whether cemented or press-fit hemiarthroplasties were more advantageous in terms of revision surgery, contralateral hip fractures, hospital length of stay, mortality rates, and survival. METHODS: All geriatric fragility hip fractures at a level 1 trauma center (2014 to 2019) were retrospectively reviewed for the fracture pattern, fixation methodology, and outcome, yielding 707 femoral neck fractures treated with hemiarthroplasty (309 cemented and 398 press fit). The final follow-up was either date of death or final encounter. Major end points were revision surgery, contralateral fracture, and death. A Z-score test of two proportions was used for dichotomous variables, and a two-tailed t -test was used for continuous variables. Cox proportional hazard was used for revision surgery-free survival between groups, adjusting for age, sex, and American Society of Anesthesiologists status. RESULTS: Patients who underwent press-fit hemiarthroplasty had a significantly higher rate of revision surgery (7.8% vs 3.9%; P = 0.006). Press-fit cases had a trend toward a decreased risk of contralateral fracture (13% vs 9.8%; P = 0.12), although this did not reach significance. Both groups had similar length of stay ( P = 0.08) and death rates ( P = 0.39). Of those who died, there was a trend toward longer survival in patients who received a press-fit hemiarthroplasty (413 vs 615 days; P < 0.001). There was a trend toward longer survival without repeat surgery in the cemented group without reaching significance (hazard ratio, 0.66 [0.34 to 1.23]; P = 0.201). CONCLUSION: In this study, we found a markedly longer survival time after press-fit hemiarthroplasty, which we believe reflects surgeons' tendencies to cement the femoral prosthesis in patients with more comorbidities. However, press-fit hemiarthroplasties were more likely to result in repeat procedures on the same hip. Displaced geriatric femoral neck fractures may benefit from a cemented rather than press-fit hemiarthroplasty.

Cadaveric Examination of the Radiographic Safe Zone for Open Reduction and Internal Fixation of the Calcaneus Posterior Facet.

Background: The purpose of this study is to define a safe zone for screw placement on a lateral radiograph of the calcaneus taking into account the lateral to medial convexity of the posterior facet. Such findings may serve to improve surgical quality during open reduction and internal fixation (ORIF) of the posterior facet of the calcaneus. Methods: Eleven cadaveric calcanei were harvested and the articular margins of the posterior facet were outlined with a radiopaque wire. Lateral radiographs, similar to those used for intraoperative fluoroscopy, of each specimen were obtained and calibrated to a standardized marker. The proximal-to-distal length of the posterior facet was then divided into quadrants. The greatest height difference between the superolateral and inferomedial surfaces outlined by the radiopaque marker were measured in the 2 most posterior quadrants, as screw insertion in this area would be mostly likely to risk screw penetration during ORIF. Results: The average distance from the osseous surface to the radiographic marker was 3.3 ± 1.2 mm in the most posterior quadrant (fourth quadrant) and 3.2 ± 1.6 mm in the quadrant just anterior to this (third quadrant). The range for unsafe screw placement was 1.7 to 5.6 mm below the osseous surface in the fourth quadrant and 1.1 to 6.6 mm in the third quadrant. Conclusion: Intraoperative radiographic assessment of the safety of subchondral posterior facet screws does not correlate to its osteology. Because of the superolateral to inferomedial convexity of the posterior facet of the calcaneus, overly long screws may appear to be radiographically intraosseous, though in actuality the screw may be intra-articular. On average, screws placed in the fourth quadrant of the facet are at less risk if 3.3 mm inferior to the upper margin of the osseous shadow on fluoroscopic imaging and 3.2 mm inferior in the third quadrant. Though limited by a small sample size, this study sets a foundation for future research into this complex osteology. Level of Evidence: Level V, mechanism-based reasoning.

The case for decreased surgeon-reported complications due to surgical volume and fellowship status in the treatment of geriatric hip fracture: An analysis of the ABOS database.

INTRODUCTION: American orthopaedists are increasingly seeking fellowship sub-specialization. One proposed benefit of fellowship training is decrease in complications, however, few studies have investigated the rates of medical and surgical complications for hip fracture patients between orthopedists from different fellowship backgrounds. This study aims to investigate the effect of fellowship training and case volume on medical and surgical outcomes of patient following hip fracture surgical intervention. METHODS: 1999-2016 American Board of Orthopedic Surgery (ABOS) Part II Examination Case List data were used to assess patients treated by trauma or adult reconstruction fellowship-trained orthopedists versus all-other orthopaedists. Rates of surgeon-reported medical and surgical adverse events were compared between the three surgeon cohorts. Using binary multivariate logistic regression to control of demographic factors, independent factors were evaluated for their effect on surgical complications. RESULTS: Data from 73,427 patients were assessed. An increasing number of hip fractures are being treated by trauma fellowship trained surgeons (9.43% in 1999-2004 to 60.92% in 2011-2016). In multivariate analysis, there was no significant difference in type of fellowship, however, surgeons with increased case volume saw significantly decreased odds of complications (16-30 cases: OR = 0.91; 95% CI: 0.85-0.97; p = 0.003; 31+ cases: OR = 0.68; 95% CI: 0.61-0.76; p<0.001). Femoral neck hip fractures were associated with increased odds of surgical complications. DISCUSSION: Despite minor differences in incidence of surgical complications between different fellowship trained orthopaedists, there is no major difference in overall risk of surgical complications for hip fracture patients based on fellowship status of early orthopaedic surgeons. However, case volume does significantly decrease the risk of surgical complications among these patients and may stand as a proxy for fellowship training. Fellows required to take hip fracture call as part of their training regardless of fellowship status exhibited decreased complication risk for hip fracture patients, thus highlighting the importance of additional training.

Comparing Venous Thromboembolism Prophylactic Agents After Hip Fracture Surgery: A National Database Study.

INTRODUCTION: Although the use of venous thromboembolism (VTE) chemoprophylaxis has markedly reduced VTE rates after hip fracture surgery, few studies have directly compared the efficacy of different anticoagulant agents in this setting. The purpose of this study was to compare outcomes of Lovenox, Eliquis, or Coumadin as VTE prophylaxis after hip fracture surgery. METHODS: The PearlDiver MHip national database was queried for patients older than 60 years undergoing first-time hip fracture surgery with no concurrent pelvic or distal femoral fractures. Prescriptions for Lovenox, Eliquis, or Coumadin were identified. Univariate and multivariate analyses of patient characteristics, 90-day incidences of VTE, adverse events, and readmissions were compared. Odds ratios (ORs) were calculated, and significance was set at P < 0.01 based on Bonferroni adjustment. RESULTS: A total of 11,384 patients were identified, with the Lovenox used for 6835 patients (60.0%), Eliquis for 1092 patients (9.6%), and Coumadin for 3457 patients (30.4%). The prevalence of 90-day VTE in the Lovenox, Eliquis, and Coumadin groups was 3.1%, 3.8%, and 5.0%, respectively (P < 0.001). Multivariate analyses adjusting for demographic and comorbidity profiles were conducted with Lovenox as the referent. Those on Eliquis had significantly lower transfusions (OR 0.52, P = 0.005), but similar rates of other outcomes including VTE (P > 0.01). Conversely, patients on Coumadin had significantly greater odds of any adverse event (OR 1.18, P < 0.001) and VTE (OR 1.58, P < 0.001). DISCUSSION: In evaluating Lovenox, Eliquis, and Coumadin as VTE chemoprophylactic agents after hip fracture surgery in anticoagulant-naïve patients, Lovenox and Eliquis had similar 90-day VTE, whereas patients on Coumadin had greater odds of 90-day VTE. Interestingly, patients on Eliquis had nearly two-fold lower odds of transfusions compared with patients on Lovenox. Although consensus on the optimal VTE prophylactic agent after hip fracture surgery does not exist, Eliquis and Lovenox may be comparable options and seem to be more effective than Coumadin.

COVID-positive ankle fracture patients are at increased odds of perioperative surgical complications following open reduction internal fixation surgery.

INTRODUCTION: Ankle fractures have continued to occur through the COVID pandemic and, regardless of patient COVID status, often need operative intervention for optimizing long-term outcomes. For healthcare optimization, patient counseling, and care planning, understanding if COVID-positive patients undergoing ankle fracture surgery are at increased risk for perioperative adverse outcomes is of interest. METHODS: The COVID-19 Research Database contains recent United States aggregated insurance claims. Patients who underwent ankle fracture surgery from April 1st, 2020 to June 15th, 2020 were identified. COVID status was identified by ICD coding. Demographics, comorbidities, and postoperative complications were extracted based on administrative data. COVID-positive versus negative patients were compared with univariate analyses. Propensity-score matching was done on the basis of age, sex, and comorbidities. Multivariate regression was then performed to identify risk factors independently associated with the occurrence of 30-day postoperative adverse events. RESULTS: In total, 9,835 patients undergoing ankle fracture surgery were identified, of which 57 (0.58%) were COVID-positive. COVID-positive ankle fracture patients demonstrated a higher prevalence of comorbidities, including: chronic kidney disease, diabetes, hypertension, and obesity (p<0.05 for each). After propensity matching and controlling for all preoperative variables, multivariate analysis found that COVID-positive patients were at increased risk of any adverse event (odds ratio [OR] = 3.89, p = 0.002), a serious adverse event (OR = 5.48, p = 0.002), and a minor adverse event (OR = 3.10, p = 0.021). DISCUSSION: COVID-positive patients will continue to present with ankle fractures requiring operative intervention. Even after propensity matching and controlling for patient factors, COVID-positive patients were found to be at increased risk of 30-day perioperative adverse events. Not only do treatment teams need to be protected from the transmission of COVID in such situations, but the increased incidence of perioperative adverse events needs to be considered.

Clinical Characteristics and Perioperative Complication Profiles of COVID-19-Positive Patients Undergoing Hip Fracture Surgery.

INTRODUCTION: The coronavirus 2019 (COVID-19) pandemic disease has imposed an unprecedented degree of stress on healthcare systems. This study aimed to understand whether COVID-19 positivity is associated with an increased risk of adverse outcomes after geriatric hip fracture surgery. METHODS: From a national administrative claims data set, patients who underwent hip fracture surgery from April 1, 2020, to December 1, 2020 were selected for analysis. COVID-19-positive status was assessed by the emergency International Classification of Diagnoses, 10th Revision, COVID-19 code within 2 weeks before the surgery. Demographic, comorbidity, and 30-day postoperative adverse event information were extracted. Logistic regression before and after 10:1 propensity matching was performed to identify patient risk factors associated with the occurrence of postoperative adverse events. RESULTS: Of 42,002 patients who underwent hip fracture surgery, 678 (1.61%) were identified to be positive for COVID-19 infection. No significant differences in age, sex, and procedure type were found between COVID-19-positive and COVID-19-negative groups, but the COVID-19-positive patients demonstrated a higher incidence of several comorbidities. These differences were no longer significant after matching. After matching, the COVID-19-positive group had a higher incidence of any, serious, and minor adverse events (P < 0.001 for all). Controlling for preoperative variables, COVID-19 positivity was associated with an increased risk of experiencing any adverse events (odds ratio [OR] = 1.62, 95% confidence interval [95% CI] = [1.37 to 1.92], P < 0.001), serious adverse events (OR = 1.66, 95% CI = [1.31 to 2.07], P < 0.001), and minor adverse events (OR = 1.59, 95% CI = [1.34 to 1.89], P < 0.001). DISCUSSION: After matching and controlling for confounding variables, COVID-19-positive hip fracture patients had increased odds of multiple postoperative events. Clinicians caring for this vulnerable geriatric population should be mindful of this risk to improve the care for these patients during the ongoing global pandemic.

Posterior Talar Body Fracture With Flexor Hallucis Longus Incarceration: A Case Report & Literature Review.

CASE: A 58-year-old man presented with entrapment of the flexor hallucis longus (FHL) tendon between fractured fragments of the talar body. The patient was successfully treated with atypical operative approaches to release the tendon and reduce the fracture. At the 1-year follow-up, the patient remained asymptomatic with the ability to extend and flex of all toes. This case illustrates a unique surgical approach for this presentation. CONCLUSIONS: With proper utilization of positioning and fluoroscopy, posterior talar body fractures with entrapment of the FHL can be stabilized and corrected with dual use of medial-sided approaches.

Vector Appropriate Distraction and Reduction of a Neglected Trimalleolar Fracture-Dislocation Performed with a Temporary Intraoperative External Fixator.

Traumatic fractures of the ankle can occur with concomitant tibiotalar dislocations, necessitating complex treatment. These injuries have higher rates of loose bodies, open injuries, postoperative complications, and worse patient reported outcomes compared to ankle fractures without dislocation. Patients with neglected or delayed presentations are associated with even higher rates of postoperative complications and worse outcomes compared to acute injuries. The chronicity of the injury leads to soft tissue contractures and malunited fractures, obligating a care plan which involves gradual reduction with a multiplanar external fixator with or without internal fixation at a later date. We discuss a 60-year-old homeless man who presented four weeks after an open trimalleolar fracture-dislocation and was definitely treated with an acute one-stage procedure. Anatomic reduction and stable fixation was achieved through a lateral malleolus osteotomy, soft tissue releases, TAL, and a temporary intraoperative external fixator. This technique was advantageous in this instance of anticipated patient noncompliance. We advocate for the judicious use of the described technique in similar challenging situations.

The Effect of Feedback on Surgeon Performance: A Narrative Review.

Surgeons play a critical role in the healthcare community and provide a service that can tremendously impact patients' livelihood. However, there are relatively few means for monitoring surgeons' performance quality and seeking improvement. Surgeon-level data provide an important metric for quality improvement and future training. A narrative review was conducted to analyze the utility of providing surgeons direct feedback on their individual performance. The articles selected identified means of collecting surgeon-specific data, suggested ways to report this information, identified pertinent gaps in the field, and concluded the results of giving feedback to surgeons. There is a relative sparsity of data pertaining to the effect of providing surgeons with information regarding their individual performance. However, the literature available does suggest that providing surgeons with individualized feedback can help make meaningful improvements in the quality of practice and can be done in a way that is safe for the surgeons' reputation.

Reliability of Radiographic Union Scoring in Humeral Shaft Fractures.

OBJECTIVES: To establish the reliability of 2 radiographic union scoring systems for nonoperative humeral shaft fractures. DESIGN: Retrospective medical record review. Patients identified had humeral shaft fractures and radiographs at various follow-up time points, which were graded according to the both the standard (RUST) and modified radiographic union scoring systems (mRUST). SETTING: A single North American Level-1 Trauma center in Connecticut, including emergency department and clinic follow-up visits. PATIENTS/PARTICIPANTS: Forty-five adult patients (162 image sets) met the following inclusion criteria: diaphyseal humerus fracture, initial nonoperative management, and greater than 2 weeks of follow-up with imaging. INTERVENTION: All 162 image sets of anterior-posterior and lateral radiographs were scored and divided into 4 tiers based on increasing score. Anterior-posterior and lateral image sets were randomly selected from each tier for a total of 50 that were then scored by 7 different reviewers using both the RUST and mRUST systems. MAIN OUTCOME MEASURES: The intraclass correlation coefficients for the cortical and system scores for the RUST and mRUST systems. RESULTS: Interobserver reliability was 0.795 for the RUST system and 0.801 for mRUST. Intraobserver reliability was 0.909 for RUST and 0.949 for mRUST. For mRUST, 92% of values were within ± 1 point from each other. CONCLUSIONS: The RUST and mRUST systems can be applied to humeral shaft fractures with excellent reliability. They have the potential to assist in the diagnosis of humeral shaft union by providing an objective and standardized method to assess healing of bone over time.

Open pronation abduction ankle fractures associated with increased complications and patient BMI.

INTRODUCTION: Pronation abduction (PA) ankle fractures are often associated with a medial tension failure wound. Though this injury pattern was defined based on the mechanism of injury, there is a paucity of literature evaluating risk factors for understanding which patients will sustain an open PA fracture. Furthermore, how patients with these types of fractures perform relative to other open ankle fractures has not been established. We hypothesized that open PA fractures are associated with obesity and increased number of reoperations. METHODS: All patients at a single level one trauma center who received operative treatment for an ankle fracture between February 2012 to January 2019 were retrospectively identified using Current Procedural Terminology (CPT) codes. Patients with open PA ankle fractures were identified. Demographic data, body mass index, medical comorbidities, time to surgery, and reoperations were compared between open PA ankle fractures and other open ankle fracture subtypes. RESULTS: There were 22 open PA ankle fractures and 35 other open ankle fracture subtypes. The open PA fracture group had a significantly higher median and average BMI and percentage of patients with obesity. There was no difference in number of patients requiring reoperation between the two groups. When reoperation was required, patients with open PA ankle fractures were found to undergo significantly more reoperations and were significantly more likely to require arthrodesis or below knee amputation. CONCLUSIONS: Open PA ankle fractures are more often associated with obesity (BMI > 30 kg/m2) than are other open ankle fractures caused by a different mechanism. When reoperation does occur, patients with open PA ankle fractures require more reoperations and are more likely to require arthrodesis or below knee amputation that patients with other open ankle fracture subtypes. Early identification of those patients or injuries at increased risk of complications can help ensure optimal outcomes.

Total knee arthroplasty in osteogenesis imperfecta.

Osteogenesis imperfecta is a genetic disease resulting in abnormal collagen formation, with multiple clinical manifestations. Advancements in medical and surgical treatments have prolonged the life expectancy of these patients in recent decades. As a result, orthopedic surgeons are likely to be faced with the challenge of performing arthroplasty in these patients on a more frequent basis. Here, we describe a patient with osteogenesis imperfecta and subsequent severe osteoarthritis prompting primary total knee arthroplasty. This rare case presents an opportunity to explore special considerations unique to this patient population, including comorbid bone defects, the need for using extramedullary guides, careful alignment of prostheses to accommodate abnormalities in limb axes, and equipment utilization.

Pharmacologic and Radiation Therapies for Cancer-Induced Bone Loss.

Advancements in medical and radiation oncology have improved the prognosis for many cancers during the past few decades. As a result, physicians are challenged with managing a greater burden of disease for a longer time. In orthopaedics, bone loss secondary to metastatic tumor places patients at risk of impending and pathologic fractures. These events limit functional independence, lessen the quality of life, and place a financial burden on patients and their families. Thus, it is important for clinicians to be aware of measures capable of mitigating cancer-induced bone loss.

Proximal Tibiofibular Dislocation Repaired with Syndesmotic Suture Buttons: A Case Report.

INTRODUCTION: Dislocations of the proximal tibiofibular joint (PTFJ) are a relatively rare orthopedic injury. They are often repaired with open reduction internal fixation utilizing a transfixation screw. Limited data are available concerning alternative repair methods. CASE REPORT: This report details a 46-year-old male who presented with an open Type IIIA comminuted mid-shaft tibia and segmental fibula fractures after being struck by a car traveling 70mph. Computed tomography confirmed comminuted and displaced tibia and fibula fractures with PTFJ dislocation as well as air tracking through the anterior compartment of the leg communicating with the knee joint. He underwent open reduction internal fixation with intramedullary nailing of his tibial shaft fracture and PTFJ syndesmosis repair with two suture buttons. X-ray at post-operative follow-up 2 years later showed complete healing without evidence of failure or hardware loosening. CONCLUSION: This case illustrates a patient treated with suture buttons, which provides an alternative option in treating PTFJ dislocations with a reported decreased likelihood of hardware removal and faster return to work.

Drosophila muller f elements maintain a distinct set of genomic properties over 40 million years of evolution.

The Muller F element (4.2 Mb, ~80 protein-coding genes) is an unusual autosome of Drosophila melanogaster; it is mostly heterochromatic with a low recombination rate. To investigate how these properties impact the evolution of repeats and genes, we manually improved the sequence and annotated the genes on the D. erecta, D. mojavensis, and D. grimshawi F elements and euchromatic domains from the Muller D element. We find that F elements have greater transposon density (25-50%) than euchromatic reference regions (3-11%). Among the F elements, D. grimshawi has the lowest transposon density (particularly DINE-1: 2% vs. 11-27%). F element genes have larger coding spans, more coding exons, larger introns, and lower codon bias. Comparison of the Effective Number of Codons with the Codon Adaptation Index shows that, in contrast to the other species, codon bias in D. grimshawi F element genes can be attributed primarily to selection instead of mutational biases, suggesting that density and types of transposons affect the degree of local heterochromatin formation. F element genes have lower estimated DNA melting temperatures than D element genes, potentially facilitating transcription through heterochromatin. Most F element genes (~90%) have remained on that element, but the F element has smaller syntenic blocks than genome averages (3.4-3.6 vs. 8.4-8.8 genes per block), indicating greater rates of inversion despite lower rates of recombination. Overall, the F element has maintained characteristics that are distinct from other autosomes in the Drosophila lineage, illuminating the constraints imposed by a heterochromatic milieu.

One-lung ventilation for surgical repair of thoracic aortic aneurysm.

Advances in the surgical approach to thoracic aortic aneurysm repairs have led to the increasing use of one-lung ventilation. Today's practice of cardiothoracic and vascular anesthesia requires a clear understanding of the techniques available for lung separation and the technical skills necessary to employ them. In this article, we discuss and evaluate the options for one-lung ventilation in thoracic aortic aneurysm repair with regard to preoperative, intraoperative, and postoperative management.