Elective Knee Arthroplasty Research Articles

The Impact of an Algorithm-Guided Management of Preoperative Anemia in Perioperative Hemoglobin Level and Transfusion of Major Orthopedic Surgery Patients

The aim of this study was to evaluate a laboratory-guided therapeutic algorithm of preoperative anemia. 335 patients with elective hip or knee arthroplasty were included in this retrospective before-after study. Group I (n = 101) underwent conventional preoperative procedures before algorithm implementation. Group II (n = 234) underwent algorithm-guided preoperative anemia management. A hemoglobin-level of 13 g/dL was the therapeutic cut-off for men and women. Reticulocyte hemoglobin content (CHr) and soluble transferrin receptor (sTfR)/log ferritin ratio were used in the form of the Thomas plot. Iron deficiency (ID) was substituted with 1000 mg iron intravenous (i.v.) and 10000 international units (I.U.) of erythropoiesis-stimulating agent (ESA) subcutaneous (s.c.) or i.v., anemia of chronic disease (ACD) (without functional ID) with 40000 I.U. ESA s.c. or i.v and additionally 200 mg iron i.v. Substituted anemic patients in Group II (n = 32) showed a distinctly higher preoperative (Hb-median 13 versus 11.95 g/dL) (P < 0.01) and postoperative (Hb-median 9.75 versus 9.0 g/dL) (P < 0.05) Hb level compared with untreated anemic patients in Group I (n = 24). In Group II red blood cell (RBC) units (35 units/234 patients) were reduced by 44% compared with Group I (27 units/101 patients). Algorithm-guided preoperative anemia management raises perioperative Hb-level and reduces blood use.

Modern techniques in total knee arthroplasty

Total knee arthroplasty or replacement is a common elective orthopaedic operation. It is usually performed for osteoarthritis and uses metal to replace the articular surfaces of the tibia and femur. When a senior orthopaedic trainee demonstrates a good understanding of the principles behind this procedure, he or she is gradually allowed to perform this surgery under supervision. This course reassures trainees, and their consultants, that they have understood why the surgery is performed as well as how it is performed. The course is run by the medical education department of Depuy, a Johnson and Johnson company. The topics discussed are generic and are not specific to any particular type of implant. This two day course is for trainees in orthopaedic surgery and would suit any trainee who is getting exposure to elective knee arthroplasty clinics and theatre. There were 40 people on the course I attended. Although it is aimed at specialty doctors and specialty trainees in their third year and above, there were some core trainees present. This two day course …

Thromboembolic and Bleeding Events Following Elective Hip and Knee Arthroplasty Using Oral Factor Xa Inhibitor

AbstractAbstract 501 Introduction & Purpose:Rivaroxaban is an oral Factor Xa inhibitor which has been licensed in Canada since 2008 and the United States since 2011 for the prevention of thromboembolic events following total hip and total knee arthroplasties. Multicentre research trials have shown clinical efficacy for prevention of deep venous thrombosis (DVT) and pulmonary embolism (PE). The aim of this study was to prospectively document the incidence and timing of thromboembolic and bleeding events in patients who received rivaroxaban as the primary prophylaxis in clinical practice. Methods:Prospective, observational study of patients given oral Factor Xa inhibitor (rivaroxaban) following primary and revision Total Hip Arthroplasty (THA) and Total Knee Arthroplasty (TKA). All patients were approached to participate and consent obtained. Patients treated with Rivaroxaban 10 mg po daily starting Post-Operative Day (POD) #1 and continued for 15 days. This protocol was approved for use at this institution and is NOT consistent with manufacturer’s recommended dosing. All participants were followed up at 6 weeks and 3 months. Doppler ultrasound or venograms used to diagnose symptomatic proximal DVT at or above the popliteal vein. Spiral CT angiogram, angiogram or ventilation/perfusion V/Q scan were used to diagnose PE. All Doppler Ultrasound reports were reviewed by a radiologist to confirm findings and all spiral CT, CT angiogram or ventilation/perfusion scans or images were reviewed (where possible) to verify findings. Bleeding complications were documented as ‘on prophylaxis' starting 2 hours after first dose of anticoagulant therapy until 24 hours after the 15thdose. All major and non-major bleeding events were reviewed by an internist to confirm severity of bleeding episode. Event rates are reported. Data reported on consented patients only. Research ethics approval was obtained for this study. Results:From June 2010 to Dec 2011, 2888 patients underwent total joint arthroplasty. Two thousand five hundred and thirty-five (88%) agreed to participate in the study. One hundred and fifty patients were treated with thromboprophylaxis other than rivaroxaban. Two thousand three hundred and forty-two were followed up at 3 months (98%). Forty-three patients were lost to follow-up. Complete data on 2342 patients is reported: 905 men, 1437 women with mean age 66 years. Total knees 1353 (primary 1229, revision 123, uni 1). Total hips 989 (primary 899, revision 90). DVT:Three DVT were reported at 6 weeks. Nine additional DVT's were reported at 3 months: 5 primary TKA and 6 Primary THAs 1 Rev THA. Total DVT= 12/2342= 0.5% (see Fig 1). PE:There were 7 confirmed PE during the first week post op: 6 primary TKA and 1 primary THA. Three additional PE's 6 weeks: 3 THA and 1 TKA. Five additional PE's reported at 3 months:4 THA and 1 TKA. Total PE 16/2342=0.7% (See Fig 2). Death:There have been 4 perioperative deaths. None were related to surgery, DVT, pulmonary embolism or bleeding. Bleeding:No major and 9 non-major surgical-site bleeds occurred. All but one were in primary THA. One major and 6 non-major non-surgical site bleeds occurred in patients who received rivaroxaban. Two additional major Non-surgical site bleeds occurred after having received rivaroxaban: one patient received only one dose of rivaroxaban and the other occurred 3–4 days after completion of treatment. Overall Major bleeds 0.04% and Non-Major bleeds 15/2342=0.6%. Transfusion:One hundred and fourteen patients (5%) received blood transfusions. Transfusion rates by procedure: unilateral THA 4%, Bilateral THA 40%, RTHA 27, unilateral PTKA 3%, bilateral TKA 16%,unicompartmental knee 0% and revision TKA 6%. No routine blood salvage or drains used for primary arthroplasties. Conclusions:The incidence of thromboembolic events within a period of 3 months was 12/2342=0.6% for DVT and 16/2342=0.7% for PE. The incidence of major bleeding was 0.04%. There were no deaths related to DVT, PE or bleeding. Preliminary results are surprising for the number of pulmonary emboli which occurred while patients were still in hospital and for the number of DVT's which occurred between 6 weeks and 3 months. The early PE's tended to occur in primary TKA. The late events tended to occur in primary THA and TKA. [Display omitted] [Display omitted] Disclosures:Murnaghan:Bayer Healthcare: Honoraria, Research Funding. Off Label Use: rivaroxaban is used for thromboprophylaxis after total joint replacement. our protocol gives first dose on day after surgery. Gollish:Bayer Healthcare: Honoraria, Research Funding.

Dabigatran etexilate: Another Double-Edged Drug?

The important limitations and drawbacks of classical parenteral (heparin, low molecular weight heparin and fondaparinux) or oral (vitamin K antagonists) anticoagulants have prompted the development of novel agents that directly inhibit either thrombin or activated factor X (FXa), two key serine proteases in the coagulation cascade. Currently, two oral anticoagulants (dabigatran etexilate, a direct thrombin inhibitor, and rivaroxaban, an inhibitor of FXa) are approved in more than 70 countries for prevention of venous thromboembolism in patients undergoing elective hip or knee arthroplasty, and in the United States and Europe for prophylaxis of stroke and systemic embolism in patients with non-valvular atrial fibrillation [1, 2]. Thrombin and FXa are classically known by their roles in the coagulation cascade, but in addition to their functions in hemostasis in recent years it has been increasingly recognized that they may exert pleiotropic effects in several cell types, acting as signaling molecules through proteaseactivated receptors (PARs). Specifically, thrombin influences diverse physiological and pathological processes, such as inflammation and atherosclerosis [3, 4] Atherosclerosis is characterized by the accumulation of lipids, fibrous tissue and cells in the subendothelial space of large arteries (mainly the coronary, carotid and cerebral arteries). These materials form atheromatous plaques that grow over the years without causing apparent symptomatology until flow-limiting stenosis leads to ischemia, or rupture of the plaque causes thrombus formation [5]. The subsequent clinical manifestations (coronary heart disease and stroke), remain one of the leading causes of disability and death in most industrialized countries and worldwide. Although initially atherosclerosis was considered a mere lipid storage disease, it is now recognized as a phenomenon of inflammatory nature [6–8]. Thrombin is one of the molecules that can contribute to the establishment and propagation of inflammatory processes in atherosclerosis [9]. By exerting pro-inflammatory actions, thrombin may modulate the formation of atherosclerotic lesions in several phases of this complex process. Thus, in initial stages of atherosclerosis thrombin may act as an inductor of endothelial dysfunction [10, 11], increasing the permeability of the endothelial barrier [12, 13] and inducing the adhesion and transmigration of leukocytes by increasing the expression of leukocyte adhesion molecules such as vascular cell adhesion molecule-1 (VCAM-1), intercellular cell adhesion molecule-1(ICAM-1) and E-selectin [14–16] and chemokines such as monocyte chemoattractant protein-1 (MCP1) in endothelial cells [17]. In more advanced stages, lesions grow by migration of new inflammatory cells, proliferation of smooth muscle cells and extracellular lipid accumulation, and they finally are covered by a fibrous cap consisting of smooth muscle cells and extracellular matrix. At this stage, sustained inflammation inside the plaque is a key factor promoting the growth and destabilization of the lesions. Thus, localized inflammation and the synthesis by macrophages of various proteases that degrade the extracellular matrix (matrix metalloproteinases), contribute to the weakening of the fibrous cap and to plaque instability and rupture. Thrombin also facilitates and exacerbates these later J. C. Laguna :M. Alegret (*) Pharmacology Unit, School of Pharmacy, University of Barcelona, Diagonal 643, 08028 Barcelona, Spain e-mail: alegret@ub.edu

Venous thromboembolism and its prophylaxis in elective knee arthroplasty: An international perspective

IntroductionPatients undergoing knee arthroplasty are at high risk of developing post-operative deep vein thrombosis (DVT) or a pulmonary embolus (PE). Despite best efforts, the best prophylaxis for thromboembolic disease remains controversial. This article aims to update the reader on the newest guidelines concerning venous thromboembolism (VTE) prophylaxis for elective knee arthroplasty, highlighting their inconsistencies and why variations in recommendations exist. MethodsThe Medline database and the Internet were searched for VTE prophylaxis guidelines in English. 12 guidelines were found and compared. The comparison looked at the recommendations made, the grade of recommendation, the level of evidence available for these recommendations and any inconsistencies between the guidelines. ResultsNearly all the guidelines advocate the use of low molecular weight heparin (LMWH) and Fondaparinux. There is little consensus in terms of other recommended drugs, the doses, duration and their recommendation grades. There are marked differences in the methodologies adopted by the different guideline working-groups. ConclusionThere is still uncertainty about the optimal methods of thromboprophylaxis in elective knee arthroplasty. Although there are always going to be disagreements about the endpoints amongst guideline makers, guidelines should achieve uniformity in their reporting of end-points, criteria for levels of evidence and recommendation grades, facilitating the clinician's decision-making process. Level of evidenceIIa.

Designing a strategy to implement cost-effective blood transfusion management in elective hip and knee arthroplasties: A study protocol

BackgroundTotal hip and knee arthroplasties are two of the most commonly performed procedures in orthopedic surgery. Different blood-saving measures (BSMs) are used to reduce the often-needed allogenic blood transfusions in these procedures. A recent large randomized controlled trial showed it is not cost effective to use the BSMs of erythropoietin and perioperative autologous blood salvage in elective primary hip and knee arthroplasties. Despite dissemination of these study results, medical professionals keep using these BSMs. To actually change practice, an implementation strategy is needed that is based on a good understanding of target groups and settings and the psychological constructs that predict behavior of medical professionals. However, detailed insight into these issuses is lacking. Therefore, this study aims to explore which groups of professionals should be targeted at which settings, as well as relevant barriers and facilitators that should be taken into acount in the strategy to implement evidence-based, cost-effective blood transfusion management and to de-implement BSMs.MethodsThe study consists of three phases. First, a questionnaire survey among all Dutch orthopedic hospital departments and independent treatment centers (n = 99) will be conducted to analyze current blood management practice. Second, semistructured interviews will be held among 10 orthopedic surgeons and 10 anesthesiologists to identify barriers and facilitators that are relevant for the uptake of cost-effective blood transfusion management. Interview questions will be based on the Theoretical Domains Interview framework. The interviews will be followed by a questionnaire survey among 800 medical professionals in orthopedics and anesthesiology (400 professionals per discipline) in which the identified barriers and facilitators will be ranked by frequency and importance. Finally, an implementation strategy will be developed based on the results from the previous phases, using principles of intervention mapping and an expert panel.DiscussionThe developed strategy for cost-effective blood transfusion management by de-implementing BSMs is likely to reduce costs for elective hip and knee arthroplasties. In addition, this study will lead to generalized knowledge regarding relevant factors for the de-implementation of non-cost-effective interventions and insight in the differences between implementation and de-implementation strategies.

Increasing productivity, reducing cost and improving quality in elective surgery in New Zealand: the Waitemata District Health Board joint arthroplasty pilot

In 2010, Waitemata District Health Board piloted a new model of care for total hip and knee arthroplasties. The pilot was incentive based and clinically led. The participating surgeons and anaesthetists were responsible for increasing surgical throughput. The pilot aimed to increase productivity, reduce cost and increase quality for patients. To compare costs and outcomes for elective hip and knee arthroplasties carried out at the pilot site (Waitakere Hospital) compared with the main District Health Board hospital site (North Shore Hospital (NSH)). A retrospective matched cohort study of hip and knee replacements discharged between 1 July 2010 and 31 March 2011, comparing costs and outcomes at the pilot site compared with the NSH site. Only non-complex procedures were included, and routinely collected data were used. One hundred and seventy-seven hip replacements (77 NSH, 100 pilot) and 158 knee replacements (88 NSH, 70 pilot) were analysed. Total inpatient event costs were 12% and 17% lower for hip and knee replacements, respectively, at the pilot site compared with NSH. Significant reduction in operation length (39% hip, 36% knee) and length of stay (38% hip, 39% knee) were found in the pilot groups compared with NSH. Implementation of an innovative new model in a public hospital setting has produced significant increases in productivity and reduced overall costs. This model could potentially be used in other public healthcare settings for non-complex elective surgery.

American Academy of Orthopaedic Surgeons Clinical Practice Guideline on

Jacobs, Joshua J. MD; Mont, Michael A. MD; Bozic, Kevin John MD, MBA; Della Valle, Craig J. MD; Goodman, Stuart Barry MD; Lewis, Courtland G. MD; Yates, Adolph “Chick” J. Jr. MD; Boggio, Lisa N. MD, MS; Watters, William C. III MD; Turkelson, Charles M. PhD; Wies, Janet L. MPH; Sluka, Patrick MPH; Hitchcock, Kristin MIS

Preventing Venous Thromboembolic Disease in Patients Undergoing Elective Total Hip and Knee Arthroplasty

Preventing Venous Thromboembolic Disease in Patients Undergoing Elective Total Hip and Knee Arthroplasty

Elective hip and knee arthroplasty and the effect of rivaroxaban and enoxaparin thromboprophylaxis on wound healing

Rivaroxaban is the first licensed oral direct inhibitor of factor Xa. Recent studies from the RECORD trials suggest rivaroxaban has superior efficacy compared to enoxaparin in preventing venous thromboembolism (VTE) with no significant increase in the major bleeding risk. Concerns remain regarding the incidence of minor bleeding, consequent delayed wound healing and subsequent risk of infection. The aim of this observational study was to assess the incidence of post-operative complications in patients receiving either rivaroxaban or enoxaparin thromboprophylaxis following elective hip and knee arthroplasty. A total of 258 patients undergoing elective total hip or knee arthroplasty within one NHS Trust were included. A total of 202 subjects (mean age, 70.7 years ± 10.0, 43 % men) received a daily dose of 10 mg of oral rivaroxaban and 56 (mean age, 70.9 years ± 9.8, 39 % men) had a daily subcutaneous injection of 40 mg of enoxaparin as thromboprophylaxis. Endpoints included VTE (deep vein thrombosis and pulmonary embolism), haemorrhagic wound complications, hospital re-admission, requirement for blood transfusion, minor and major bleeding and death. There were no significant differences in the incidence of VTE, requirement for blood transfusion and readmission rate between rivaroxaban and enoxaparin-treated patients. The incidence of minor bleeding (2.0 vs. 0 %) and haemorrhagic wound complications (5.0 vs. 1.8 %) were non-significantly higher in the rivaroxaban-treated group. There were no cases of pulmonary embolism, major bleeding or death in either group. Our experience with rivaroxaban in elective hip and knee arthroplasty showed no significant difference in the incidence of VTE or major bleeding. There was, however, a tendency to greater risk of minor bleeding and wound complications that were largely haemorrhagic in nature, which may have reached significance in a larger study.

Obstructive Sleep Apnea and Incidence of Postoperative Delirium after Elective Knee Replacement in the Nondemented Elderly

Postoperative delirium, a common complication in the elderly, can occur following any type of surgery and is associated with increased morbidity and mortality; it may also be associated with subsequent cognitive problems. Effective therapy for postoperative delirium remains elusive because the causative factors of delirium are likely multiple and varied. Patients 65 yr or older undergoing elective knee arthroplasty were prospectively evaluated for postoperative Diagnostic and Statistical Manual of Mental Disorders-IV delirium. Exclusion criteria included dementia, mini-mental state exam score less than 24, delirium, clinically significant central nervous system/neurologic disorder, current alcoholism, or any serious psychiatric disorder. Delirium was assessed on postoperative days 2 and 3 using standardized scales. Patients' preexisting medical conditions were obtained from medical charts. The occurrence of obstructive sleep apnea was confirmed by contacting patients to check their polysomnography records. Data were analyzed using Pearson chi-square or Wilcoxon rank sum tests and multiple logistic regressions adjusted for effects of covariates. Of 106 enrolled patients, 27 (25%) developed postoperative delirium. Of the 15 patients with obstructive sleep apnea, eight (53%) experienced postoperative delirium, compared with 19 (20%) of the patients without obstructive sleep apnea (P = 0.0123, odds ratio: 4.3). Obstructive sleep apnea was the only statistically significant predictor of postoperative delirium in multivariate analyses. This is the first prospective study employing validated measures of delirium to identify an association between preexisting obstructive sleep apnea and postoperative delirium.

A cost study of postoperative cell salvage in the setting of elective primary hip and knee arthroplasty

The increasing costs, limited supply, and clinical risks associated with allogeneic blood transfusion have prompted investigation into autologous blood management strategies, such as postoperative red blood cell (RBC) salvage. This study provides a cost comparison of transfusing washed postoperatively salvaged RBCs using an orthopedic perioperative autotransfusion device (OrthoPat, Haemonetics Corporation) versus unwashed shed blood and banked allogeneic blood. Cell salvage data were retrospectively reviewed for a sample of 392 patients who underwent primary hip or knee arthroplasty. Mean unit costs were calculated for washed salvaged RBCs, equivalent units of unwashed shed blood, and therapeutically equivalent volumes of allogeneic RBCs. No initial capital investment was required for the establishment of the postoperative cell salvage program. For patients undergoing total knee arthroplasty (TKA), the mean unit costs for washed postoperatively salvaged cells, unwashed shed blood, and allogeneic banked blood were $758.80, $474.95, and $765.49, respectively. In patients undergoing total hip arthroplasty (THA), the mean unit costs for washed postoperatively salvaged cells, unwashed shed blood, and allogeneic banked blood were $1827.41, $1167.41, and $2609.44, respectively. This analysis suggests that transfusing washed postoperatively salvaged cells using the OrthoPat device is more costly than using unwashed shed blood in both THA and TKA. When compared to allogeneic transfusion, washed postoperatively salvaged cells carry a comparable cost in TKA, but potentially represent a significant savings in patients undergoing THA. Sensitivity analysis suggests that in the case of TKA, however, cost comparability exists within a narrow range of units collected and infused.

Infection rates following hip and knee joint arthroplasty: large referral centre versus a small elective-only hospital

The aim of this study was to investigate deep infection rates following hip and knee arthroplasty at a large referral hospital and to compare these rates with a smaller hospital where only elective surgery was performed. Both hospitals were administered by the same public institution. A search of the medical records was performed for all deep infections following elective primary hip and knee arthroplasty; revision procedures were excluded as were total hip replacement and hemiarthroplasty following trauma. To be considered, a deep infection cases must have had bacterial growth confirmed on deep tissue surgical specimens or on aspiration of the joint within 1year of the index procedure. There were 14 infections confirmed following 1,160 arthroplasties at the larger hospital and 1 infection for the elective-only hospital following 466 arthroplasties. Statistical analysis showed there was a 7.06 greater chance of having an infection at the larger campus compared with the smaller campus CI (1.3, 130.7). Although there was a trend towards a greater number of infections at the larger hospital, the result was not statistically significant (P=0.06). We acknowledge there were some differences between the two study populations. We found a trend towards, but not a statistically significant difference, between infection rates at the elective-only hospital compared to the larger institution. Given the low overall rate of infection, studies with improved statistical power are needed to determine whether there is a difference in infection rates at smaller elective-only hospitals versus larger hospitals providing elective and non-elective services. The reasons for the difference are likely to be multifactorial. We hypothesise that infection rates are increased in the larger hospital where there is more procedures, both clean and contaminated being performed in the operating theatres, as well as a greater number of inpatient beds and where the hospital admits non-elective cases via its emergency department. Level-two cohort study.

Rationale and design of XAMOS: noninterventional study of rivaroxaban for prophylaxis of venous thromboembolism after major hip and knee surgery

Venous thromboembolism is a frequent and potentially life-threatening complication of orthopedic surgery. Rivaroxaban is an oral direct factor Xa inhibitor, which was shown to be effective for the prevention of venous thromboembolism after elective hip and knee arthroplasty in the RECORD study program. Rivaroxaban has the potential to overcome the limitations of the current standards of care in the prevention of venous thromboembolism. XAMOS (Xarelto® in the prophylaxis of post-surgical venous thromboembolism after elective major orthopedic surgery of hip or knee) is an international, noninterventional, parallel-group study to gain insight into the safety (major bleeding, side effects) and effectiveness (prevention of symptomatic thromboembolic events) of rivaroxaban in daily clinical practice. XAMOS will follow 15,000 patients after major orthopedic surgery in approximately 200 centers worldwide, with about 7500 patients receiving rivaroxaban and about 7500 standard of care. XAMOS will supplement the clinical data obtained in the Phase III RECORD 1, 2, 3, and 4 trials in which rivaroxaban was shown to be superior for the primary efficacy endpoints, and with a safety profile similar to that of enoxaparin after hip or knee replacement surgery. XAMOS was started in 2009 and will complete recruitment and follow-up in 2011.

Comparison of postdischarge physiotherapy versus usual care following primary total knee arthroplasty for osteoarthritis: an exploratory pilot randomized clinical trial

Objective: To evaluate a pilot trial of a postdischarge physiotherapy intervention to improve patient function versus usual physiotherapy in patients undergoing total knee arthroplasty aiming to assess: recruitment rate, feasibility and acceptability of the intervention and control, suitability of outcomes, retention and adverse events and to inform sample size calculation for a definitive trial. Design: Exploratory pilot randomized controlled trial using independent assessment. Setting: Mixed urban and rural, UK. Participants: Patients undergoing primary, elective unilateral knee arthroplasty for osteoarthritis. Intervention: Two additional home physiotherapy visits of functional weight-bearing exercises, functional task-specific training versus treatment as usual. Main outcome: Oxford Knee Score at 12 months. Secondary outcomes: completion rates, adverse events, Knee Injury and Osteoarthritis Outcome Score, leg extensor power, timed 10-m walk, timed sit-to-stand, resource use diaries. Assessments completed at baseline (pre-operatively), 3, 6 and 12 months. Results: Of 181 eligible participants 107 (59.1%) were randomized over 13 months, one participant withdrew, no adverse events. Intervention group n = 56 (mean age 67.8), control group n = 51 (mean age 70.8). The difference in mean change of Oxford Knee Scores between groups (intervention – control) at 12 months was 0.2 (95% confidence interval (CI) –3.8, 4.2), P = 0.94. Patient diaries revealed non-trial additional physiotherapy requires improved measurement. Conclusions: Successful recruitment and retention rates were achieved. The intervention appeared feasible and acceptable but may be suboptimal in intensity given recent research. A sample size of 1271 participants would be required for a fully powered randomized controlled trial using the main outcome. However new outcomes, potentially of greater validity and responsiveness, require consideration.

Preventing Venous Thromboembolic Disease in Patients Undergoing Elective Hip and Knee Arthroplasty

This guideline supersedes a prior one from 2007 on a similar topic. The work group evaluated the available literature concerning various aspects of patient screening, risk factor assessment, and prophylactic treatment against venous thromboembolic disease (VTED), as well as the use of postoperative mobilization, neuraxial agents, and vena cava filters. The group recommended further assessment of patients who have had a previous venous thromboembolism but not for other potential risk factors. Patients should be assessed for known bleeding disorders, such as hemophilia, and for the presence of active liver disease. Patients who are not at elevated risk of VTED or for bleeding should receive pharmacologic prophylaxis and mechanical compressive devices for the prevention of VTED. The group did not recommend specific pharmacologic agents and/or mechanical devices. The work group recommends, by consensus opinion, early mobilization for patients following elective hip and knee arthroplasty. The use of neuraxial anesthesia can help limit blood loss but was not found to affect the occurrence of VTED. No clear evidence was established regarding whether inferior vena cava filters can prevent pulmonary embolism in patients who have a contraindication to chemoprophylaxis and/or known VTED.

Arterial antithrombotic activity of rivaroxaban, an orally active factor Xa inhibitor, in a rat electrolytic carotid artery injury model of thrombosis

Rivaroxaban, an oral, direct factor Xa inhibitor, has been approved in several countries for thromboprophylaxis after elective hip or knee arthroplasty based on favorable benefit-risk profile and improved efficacy compared to enoxaparin in reducing the composite of symptomatic and asymptomatic deep vein thrombosis, nonfatal pulmonary embolism, and all-cause mortality. Given the potential therapeutic utility of factor Xa inhibition in arterial thrombosis, we evaluated the antithrombotic activity of rivaroxaban in a model of arterial thrombosis in anesthetized rats in which thrombotic occlusion was induced by electrolytic injury of the carotid artery. Rivaroxaban, 0.3, 1 or 3 mg/kg, enoxaparin, 10 mg/kg, or vehicle were infused intravenously to anesthetized rats and time to occlusion as well as coagulation parameters monitored following carotid electrolytic injury. Although the lowest dose of rivaroxaban (0.3 mg/kg) did not prolong occlusion time compared to vehicle, rivaroxaban at 1 or 3 mg/kg prevented occlusion in all vessels during the 30-min observation period (median occlusion time >30 min), which was greater than that following a single dose of enoxaparin infused at a dose of 10 mg/kg (median time to occlusion = 21.6 min). Rivaroxaban was also effective following oral dosing at 3 mg/kg. Rivaroxaban's antithrombotic activity was paralleled by dose-dependent increases in prothrombin time (PT) and activated clotting time (ACT) without significant changes in activated partial thromboplastin time. Rivaroxaban also markedly increased Russell's viper venom time (RVVT) and decreased thrombin-antithrombin complex concentrations at all doses. These findings support the potential utility of rivaroxaban in arterial thrombotic disorders such as acute coronary syndrome, stroke and peripheral arterial disease.

AAOS Clinical Practice Guideline: Preventing Venous Thromboembolic Disease in Patients Undergoing Elective Hip and Knee Arthroplasty

AAOS Clinical Practice Guideline: Preventing Venous Thromboembolic Disease in Patients Undergoing Elective Hip and Knee Arthroplasty

Statins and Intracerebral Hemorrhage

A recent post hoc analysis of a large randomized trial in patients with cerebrovascular disease suggested that statins may increase the risk of intracerebral hemorrhage (ICH). To examine the association between statins and ICH in patients with recent ischemic stroke in a population-based setting. Retrospective propensity-matched cohort study with accrual from July 1, 1994, to March 31, 2008. Ontario, Canada. A total of 17872 patients aged 66 years and older who initiated statin therapy following acute ischemic stroke and were followed for a median of 4.2 years (interquartile range, 2.4-5.0 years). To enhance causal inference, we conducted several tests of specificity to exclude healthy user bias in this sample. Main Outcome Measure Hospitalization or emergency department visit for ICH defined using validated diagnosis coding. Overall, 213 episodes of ICH occurred. In the primary analysis comparing statin users with nonusers, we found no association between statins and ICH (hazard ratio=0.87; 95% confidence interval, 0.65-1.17). Subgroup and dose-response analyses yielded similar results. In tests of specificity, statin therapy was not associated with bone mineral density testing, vitamin D or B(12) screening, gastrointestinal endoscopy, or elective knee arthroplasty, suggesting that results were not due to healthy user bias or differences in quality of care. Statin exposure following ischemic stroke was not associated with ICH.

The relation between acute changes in the systemic inflammatory response and plasma 25-hydroxyvitamin D concentrations after elective knee arthroplasty

Studies indicate that low plasma 25-hydroxyvitamin D [25(OH)D] is associated with a range of disease processes, many of which are inflammatory. However, other lipid-soluble vitamins decrease during the systemic inflammatory response, and this response may confound the interpretation of plasma 25(OH)D. The objective was to examine whether plasma 25(OH)D concentrations change during evolution of the systemic inflammatory response. Patients (n = 33) who underwent primary knee arthroplasty had venous blood samples collected preoperatively and postoperatively (beginning 6-12 h after surgery and on each morning for 5 d) for the measurement of 25(OH) D, vitamin D-binding protein, parathyroid hormone (PTH), calcium, C-reactive protein, and albumin. A final sample was collected at 3 mo. Preoperatively, most patients were 25(OH)D deficient (<50 nmol/L) and had secondary hyperparathyroidism (PTH > 5 pmol/L). Age, sex, body mass index, season, medical history, and medication use were not associated with significant differences in preoperative plasma 25(OH)D concentrations. By day 2 there was a large increase in C-reactive protein concentrations (P < 0.001) and a significant decrease in 25(OH)D of ≈40% (P < 0.001). C-reactive protein, 25(OH)D, and calculated free 25(OH)D had not returned to preoperative concentrations by 5 d postoperatively (all P < 0.001). At 3 mo, 25(OH)D and free 25(OH)D remained significantly lower (20% and 30%, respectively; P < 0.01). Plasma concentrations of 25(OH)D decrease after an inflammatory insult and therefore are unlikely to be a reliable measure of 25(OH)D status in subjects with evidence of a significant systemic inflammatory response.