Synthetic direct inhibitors of factor Xa are capable of prolonging the global anticoagulant assay times in a concentration-dependent fashion. The relative degree of thrombin generation inhibition at an equivalent prolongation is not similar to the results observed with heparins and oral anticoagulant drugs. In addition, the direct factor Xa inhibitors prolong the Russell's viper venom test (RWT) and Heptest clotting times. Ecarin clotting time (ECT) and thrombin time (TT) remain unaffected. The kinetics of factor Xa inhibition are markedly different than those observed with pentasaccharide and heparins. Therefore, the methods developed for heparins and pentasaccharides may not be applicable for the monitoring of factor Xa inhibitors. To test the feasibility of using the prothrombin time (PT), International Normalized Ratio (INR), activated partial thromboplastin time (aPTT), Heptest, thrombin time, RVVT, ECT, and a modified anti-Xa amidolytic assay, to monitor a synthetic factor Xa inhibitor, normal human pool plasma samples were spiked with a synthetic factor Xa inhibitor in the concentration range of 0 to 1 microg/mL and 0 to 25 microg/mL. Different laboratory tests were performed and INR and other ratios were calculated. The anticoagulant effects on whole blood were measured using the activated clotting time (ACT). Further studies on the effect of factor Xa inhibitor on platelet aggregation; factor II, VII, and X functional levels; and fibrinopeptide A (FPA) generation were carried out at equivalent INR levels in comparison to oral anticoagulant and antithrombin agents. FPA generation at equivalent anticoagulant level in comparison to heparin (twice the baseline) was also carried out. Factor Xa inhibitor produced a concentration-dependent prolongation of the ACT. ACT was doubled at a concentration of 4 to 5 microg/mL. There was a marked difference in the prolongation of the PT by a synthetic factor Xa inhibitor dependent on the ISI of the PT reagent used. When the results were calculated to determine INR, marked variations were noted between the recombinant thromboplastin and rabbit brain thromboplastin. The rabbit brain thromboplastin reagent gave markedly high INR values. Similar results were observed when different aPTT reagents were studied. In the anti-Xa assay, modification of the incubation time was employed to extend the proper sensitivity range. These studies warrant further investigation to understand the mechanism of action of factor Xa inhibitors.
Background: Optimal treatment of meniscal pathology continues to evolve in orthopaedic surgery, with a growing understanding of which patients benefit from which procedure and which patients might be best treated nonsurgically. In 2002, Moseley et al found no difference between arthroscopic procedures, including meniscal debridement and sham surgery, in patients with osteoarthritis of the knee. This called into question the role of routine arthroscopic debridement in these patients. Additionally, an increased interest in understanding and maintaining the function of the meniscus has more recently resulted in a greater focus on meniscal preservation procedures. Study Design: Descriptive epidemiology study. Purpose/Hypothesis: The purpose was to evaluate the trends of arthroscopic meniscal debridement and repair and the characteristics of the patients receiving these treatments, compare the differences in practice between newly trained orthopaedic sports medicine specialists and those of other specialties, and analyze if there are differences in practice by region. It was hypothesized that the American Board of Orthopaedic Surgery (ABOS) database would evaluate practice patterns of recent graduates as a surrogate for current treatment and training and, consequently, demonstrate a decreased rate of meniscal debridement. Methods: Data from ABOS Part II examinees from 2001 to 2017 were obtained from the ABOS Case List. Current Procedure Terminology (CPT) codes related to arthroscopic meniscal treatment were selected. The examination year, age of the patient, practice region, and examinee subspecialty were analyzed. Patient age was stratified into 4 groups: <30, 30 to 50, 51 to 65, and >65 years. Examinee subspecialty was stratified into sports medicine and non–sports medicine. Statistical regression analysis was performed. Results: Between 2001 and 2017, ABOS Part II examinees submitted 131,047 cases with CPT codes 29880 to 29883. Meniscal debridement volume decreased for all age groups during the study period, while repair increased. Sports medicine subspecialists were more likely than their counterparts to perform repair over debridement in patients aged younger than 30 years ( P = .0004) and between 30 and 50 years ( P = .0005). Conclusion: This study provides insights into arthroscopic meniscal debridement and repair practice trends among ABOS Part II examinees. Meniscal debridement is decreasing and meniscal repair is increasing. Younger patient age and treatment by a sports medicine subspecialty examinee are associated with a higher likelihood of repair over debridement.
Sex and age-matched wild-type and TCR transgenic mice were infected with cytomegalovirus (CMV) at 6 months of age and followed for 12 additional months to examine aging of the immune system. It was found that viral infection of C57Bl/6 mice resulted in accelerated aging of the immune system as shown by a loss of CD8+28+ cells and an accumulation of KLRG1+ T cells. CMV infection of OT-1 transgenic mice had no influence on immune aging of these mice which nonetheless demonstrated an accumulation of CD8+28− and KLRG1+ T cells with time. CD4+ T cells were unaffected in either strain of mice. Thus, immunological aging was found to be due to both cell-intrinsic and cell-extrinsic factors. Persistent viral infections may accelerate immunological aging but consideration must be given to individual variation in the aging process.
Case: A 43-year-old man suffered an irreducible posterolateral knee dislocation while snowboarding with associated tears of the anterior cruciate, posterior cruciate, medial collateral, and posterolateral corner ligaments. Two closed reduction attempts failed, and magnetic resonance imaging revealed incarcerated soft tissue from a tertiary gastrocnemius muscle head. The patient underwent open reduction and repair/reconstruction of his multiligamentous knee injury. At the 6-year follow-up, the patient did not have pain or instability and returned to recreational activities. Conclusions: This case demonstrates that a tertiary gastrocnemius muscle head, the most common anatomical variation, may complicate the closed reduction of an irreducible posterolateral knee dislocation.
Background: Although medial patellofemoral ligament (MPFL) reconstruction is well described for patellar instability, the utility of arthroscopy at the time of stabilization has not been fully defined. Purpose: To determine whether diagnostic arthroscopy in conjunction with MPFL reconstruction is associated with improvement in functional outcome, pain, and stability or a decrease in perioperative complications. Study Design: Cohort study; Level of evidence, 3. Methods: Patients who underwent primary MPFL reconstruction without tibial tubercle osteotomy were reviewed (96 patients, 101 knees). Knees were divided into MPFL reconstruction without arthroscopy (n = 37), MPFL reconstruction with diagnostic arthroscopy (n = 41), and MPFL reconstruction with a targeted arthroscopic procedure (n = 23). Postoperative pain, motion, imaging, operative findings, perioperative complications, need for revision procedure, and postoperative Kujala scores were recorded. Results: Pain at 2 weeks and 3 months postoperatively was similar between groups. Significantly improved knee flexion at 2 weeks was seen after MPFL reconstruction without arthroscopy versus reconstruction with diagnostic and reconstruction with targeted arthroscopic procedures (58° vs 42° and 48°, respectively; P = .02). Significantly longer tourniquet times were seen for targeted arthroscopic procedures versus the diagnostic and no arthroscopic procedures (73 vs 57 and 58 min, respectively; P = .0002), and significantly higher Kujala scores at follow-up were recorded after MPFL reconstruction without arthroscopy versus reconstruction with diagnostic and targeted arthroscopic procedures (87.8 vs 80.2 and 70.1, respectively; P = .05; 42% response rate). There was no difference between groups in knee flexion, recurrent instability, or perioperative complications at 3 months. Diagnostic arthroscopy yielded findings not previously appreciated on magnetic resonance imaging (MRI) in 35% of patients, usually resulting in partial meniscectomy. Conclusion: Diagnostic arthroscopy with MPFL reconstruction may result in findings not previously appreciated on MRI. Postoperative pain, range of motion, and risk of complications were equal at 3 months postoperatively with or without arthroscopy. Despite higher Kujala scores in MPFL reconstruction without arthroscopy, the relationship between arthroscopy and patient-reported outcomes remains unclear. Surgeons can consider diagnostic arthroscopy but should be aware of no clear benefits in patient outcomes.
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