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Background: Vaccination for hepatitis B virus (HBV) after chemotherapy among pediatric patients with acute leukemia is still a debated issue. We investigated HBV immunity before and after chemotherapy and assessed immune response to re-vaccination after chemotherapy. Methods: We retrospectively analyzed data of children and adolescents aged

Background Childhood-onset Systemic Lupus Erythematosus is a rare disease, with more than 50% of patients presenting with cytopenia of a decrease in at least one cell line. Objectives The purpose of this study was to evaluate whether clinical characteristics differed according to hematologic manifestation. Methods We retrospectively reviewed the presenting clinical and laboratory manifestations for 40 pediatric SLE patients (mean age 13.4 years, range 0-18 years), with leukopenia (n=12) and thrombocytopenia (n=15). Variables including age, inflammatory markers (ESR and CRP), prothrombin time, complement system (C3, C4 and CH50), immunoglobulin (IgG, IgA and IgM), Lupus anticoagulant ratio, antinuclear antibody, anti-phospholipid antibody, anti-platelet antibodies, anti β2-glycoprotein antibody, anti-cardiolipin antibody, anti-smith antibody and anti-dsDNA antibody levels were compared according to grouping by presence of leukopenia ( Results Patients with cytopenia showed younger age at diagnosis than without (mean 13.1 vs. 15.2 years, p=0.0031 for leukopenia and 12.8 vs. 15.2 years, p=0.014 for thrombocytopenia), although the onset of puberty might not contribute to cytopenia. Patients with leukopenia showed lower C3 level than without (mean 44.7 vs. 73.7, p=0.013). Patients with thrombocytopenia showed lower anti-dsDNA titer than without (mean 94.1 vs. 259.8, p=0.038), and was more often negative for anti-platelet antibody (Ib/IX). There were no statistical differences among other variables. Also, there was no significant difference in one cell line decrement compared with both. Conclusion Pediatric SLE patients with leukopenia and thrombocytopenia in our study may independently decrease the levels of C3 and anti-dsDNA/anti-platelet (Ib/IX) antibody, suggesting respective pathologic pathways that do not affect each other. Disclosure of Interests None declared

Rationale: Pneumocystis jirovecii causes severe pneumonia in immunocompromised hosts. Human immunodeficiency virus infection, malignancy, solid organ or hematopoietic cell transplantation, and primary immune deficiency compose the risk factors for Pneumocystis pneumonia (PCP) in children, and PCP can be an initial clinical manifestation of primary immune deficiency. Patient concerns: A 5-month-old infant presented with cyanosis and tachypnea. He had no previous medical or birth history suggesting primary immune deficiency. He was diagnosed with interstitial pneumonia on admission. Diagnoses: He was diagnosed with PCP, and further evaluations revealed underlying X-linked hyper-IgM syndrome. Interventions: He was treated with trimethoprim/sulfamethoxazole for PCP, and eventually received allogeneic hematopoietic cell transplantation for hyper-IgM syndrome. Outcomes: Twenty months have passed after transplantation without severe complications. Lessons: PCP should be considered in infants presenting with severe interstitial pneumonia even in the absence of evidence of immune deficiency. Primary immune deficiency should also be suspected in infants diagnosed with PCP.

Background: Despite the introduction of a polymerase chain reaction (PCR) test for the diagnosis of respiratory viral infection (RVI), guidance on the application of this test and the management of RVI in immunocompromised children is lacking. This study evaluated the clinical characteristics of RVI and established strategies for the PCR test in children and adolescents with hematological malignancies.Methods: This study included children and adolescents with underlying hematological malignancies and respiratory symptoms, in whom a multiplex PCR test was performed. Patients in whom RVI was identified and not identified were categorized into Groups I and II, respectively. Group I was sub-divided into patients with upper and lower respiratory infections. The medical records of the enrolled patients were retrospectively reviewed.Results: A total of 93 respiratory illnesses were included. Group I included 46 (49.5%) cases of RVI, including 31 (67.4%) upper and 15 (32.6%) lower respiratory infections. Rhinovirus (37.0%) was the most common viral pathogen. Significantly more patients in Group I had community-acquired respiratory illnesses (p=0.003) and complained of rhinorrhea (p

Purpose There is no standard method for confirming the immunogenicity of acellular pertussis vaccines. We tried to develop a local standard method for evaluating the immunogenicity of the three-component of acellular pertussis vaccines which was developed by a Korean local company. Materials and methods The developed pertussis antigens (pertussis toxin, filamentous hemagglutinin, pertactin) were evaluated by in-house enzyme-linked immunosorbent assay (ELISA) using 189 negative sera, 25 positive sera, and 73 paired sera (pre- and post-Tdap [tetanus, diphtheria, and acellular pertussis] vaccinated sera). ELISA units were calculated by the reference line method, compared with World Health Organization reference sera, and the cut-off value was calculated using negative sera. Results When compared to National Institute for Biological Standards and Control control antigen (NIBSC) control antigens, the developed pertussis toxin (PT) and filamentous haemagglutinin (FHA) antigens were 203.48 and 61.60 IU/µg, respectively. Each in-house ELISA was established by validating the coefficients of variation % (PT, 11.53%; FHA, 8.60%; pertactin [PRN], 9.86%) obtained from the results of inter- and intra-assay variation. Also, the cut-off values of PT, FHA, and PRN were 11.65, 38.95, and 5.66 EU/mL, respectively. The distributions of antibody levels in paired showed that 93.15% (68/73) in anti-PT IgG, 97.26% (72/73) in anti-FHA IgG, and 100% in anti-PRN IgG were higher than a 100% increase after vaccination. Additionally, the values of 89.04% (65/73) in anti-PT IgG, 97.26% (72/73) in anti-FHA IgG, and 100% in anti-PRN IgG were below each cut-off point. Conclusion We established an in-house ELISA method using self-developed antigens, and these immunoassays have provided a way to standardize measuring the immunogenicity of newly developed vaccines, through single- and dual-serology.

Recurrent macrophage activation syndrome (MAS) is very rare. We present the case of an adolescent boy with human leukocyte antigen (HLA) B27-positive ankylosing spondylitis (AS), who experienced episodes of recurrent MAS since he was a toddler. A 16-year-old boy was admitted because of remittent fever with pancytopenia and splenomegaly after surgical intervention for an intractable perianal abscess. He had been diagnosed with hemophagocytic lymphohistiocytosis (HLH) 4 different times, which was well controlled with intravenous immunoglobulin and steroids since the age of 3. We were unable to identify the cause for the HLH. He remained symptom-free until the development of back pain and right ankle joint pain with swelling at 15 years of age. He was diagnosed with HLA B27-positive AS with bilateral active sacroiliitis. He showed symptom aggravation despite taking naproxen and methotrexate, and the symptoms improved with etanercept. On admission, his laboratory data showed leukopenia with high ferritin and triglyceride levels. Bone marrow biopsy examination showed histiocytic hyperplasia with hemophagocytosis. There was no evidence of infection. He received naproxen alone, and his symptoms and laboratory data improved without any other immunomodulatory medications. Genetic study revealed no primary HLH or inflammasome abnormalities. In this case, underlying autoimmune disease should have been considered as the cause of recurrent MAS in the young patient once primary HLH was excluded.

This meta-analysis was designed to evaluate the effects of computer navigation on blood conservation after total knee arthroplasty (TKA) by comparing postoperative blood loss and need for allogenic blood transfusion in patients undergoing computer navigation and conventional primary TKAs. Studies were included in this meta-analysis if they compared change in haemoglobin concentration before and after surgery, postoperative blood loss via drainage or calculated total blood loss, and/or allogenic blood transfusion rate following TKA using computer navigation and conventional methods. For all comparisons, odds ratios and 95 % confidence intervals (CI) were calculated for binary outcomes, while mean difference and 95 % CI were calculated for continuous outcomes. Twelve studies were included in this meta-analysis. The change in haemoglobin concentration was 0.39 g/dl lower with computer navigation than with conventional TKA (P = 0.006). Blood loss via drainage was 83.1 ml (P = 0.03) lower and calculated blood loss was 185.4 ml (P = 0.002) lower with computer navigation than with conventional TKA. However, the need for blood transfusion was similar for the two approaches (n.s.). The primary TKA with computer navigation was effective in reducing haemoglobin loss and blood loss, but had no effect on transfusion requirement, compared with conventional primary TKA. These findings suggest the importance of analysing several blood loss parameters, because each may not always accurately reflect true postsurgical bleeding. Meta-analysis, Level III.

This study involved 35 knees undergoing biplane medial open-wedge high tibial osteotomy (OWHTO) to assess the axial rotation of the distal tibia. The distal tibiae were internally rotated by 3.0° ± 7.1° after OWHTO. The opening width showed a Pearson correlation coefficient of -0.743 (P < .001), and the tuberosity osteotomy angle showed that of -0.678 (P < .001) with distal tibial rotation. However, changes in hip-knee-ankle angle, medial proximal tibial angle, and posterior tibial slope were not significantly correlated with the change in distal tibial rotation. In conclusion, there was an unintended tendency of increasing internal rotation of the distal tibia after biplane medial OWHTO, and this tendency was positively related to the opening width and tuberosity osteotomy angle.

Perioperative blood transfusions are common in total hip arthroplasty because of preoperative anemia and perioperative blood loss. Perioperative anemia and the need for allogeneic blood transfusion are related with increased morbidity. To reduce perioperative allogeneic blood transfusion, keeping the preoperative hemoglobin level above 12.0 g/dL is important in orthopedic patients. By using the anti-fibrinolytic agent or perioperative cell salvage, reduce intraoperative blood loss is very important for the reduction of perioperative blood loss. As a transfusion trigger, low hemoglobin is another important target to reduce the transfusion rate. Because blood management is closely connected with prognosis, it has become a new challenge in orthopedic surgery.

Purpose The current study aimed to investigate the association between the number of remaining teeth and bone mineral density (BMD) using data from the Korean National Health and Nutrition Examination Survey (KNHANES) 2008–2010. Methods This study enrolled 7315 Korean subjects (3364 men over 50 years of age and 3951 postmenopausal women). BMD was measured using dual-energy X-ray absorptiometry at three sites: the total femur (TF), femur neck (FN), and lumbar spine (LS). The number of teeth present was categorized into four groups (≤10, 11–20, 21–25, and ≥26 teeth). Results More remaining teeth were significantly associated with a higher BMD at the TF, FN, and LS in postmenopausal women after adjusting for all the covariates, but not in elderly men. In both sexes, subjects with a normal BMD tended to have more remaining teeth than those who were diagnosed with osteopenia and osteoporosis. A lower prevalence of osteoporosis was also significantly associated with more remaining teeth (number of teeth ≥26) in postmenopausal women. This trend was statistically significant in osteoporosis at the FN ( p for trend = 0.019). Conclusion The number of remaining teeth was associated with osteoporosis, especially at the FN, in postmenopausal women.

Febrile seizure (FS) is a common benign seizure disorder of young children. Although upper respiratory tract infection is the cause of fever in most episodes of FS, studies to identify respiratory viruses using a multiplex polymerase chain reaction (mPCR) test have rarely been performed for children with FS. Medical records of children presenting with FS between January 2015 and December 2019 were retrospectively reviewed. Respiratory viruses identified by a rapid influenza detection test and mPCR test were investigated, and their seasonal distribution and the association between viral identification and seizure characteristics were determined. A total of 607 episodes of FS were analyzed: 81.1% of cases were generalized tonic&ndash, clonic seizures, 81.5% occurred within 24 h after fever onset, and 87.3% continued for &le, 5 min. Complex FS occurred in 17.5% of FS episodes, and epilepsy was diagnosed in 2.5% of tracked cases. Of the 138 mPCR tests performed in 235 hospitalized episodes of FS, 112 (81.2%) tested positive for respiratory viruses: rhinovirus, enterovirus, adenovirus, and influenza virus were most frequently identified. The identified respiratory viruses showed similar seasonal distributions as were observed in community-acquired respiratory tract infections. The identification of a specific respiratory virus was not significantly associated with seizure characteristics or the development of complex FS. In conclusion, respiratory viruses, showing similar seasonal distributions with community-acquired respiratory tract infections and no significant association with the severity and outcomes of FS, should not be rigorously tested for in children with FS.

Introduction Posterior wall fractures may be associated with both-column acetabular fractures. Considering the differences in the pattern of these fractures in contrast to isolated posterior wall fractures, it is currently unclear whether they can be ignored or need to be addressed surgically. Hypothesis Stable posterior wall fractures can be skillfully ignored in patients with both-column acetabular fractures operated by an ilio-inguinal approach. Material and methods We retrospectively reviewed 49 consecutive patients who were treated for both-column acetabular fractures between the years 2009 and 2018. Considering the association of posterior wall fractures, we divided the cohort into two groups: group 1 (n = 29) absence of posterior wall fractures; and group 2 (n = 20) presence of posterior wall fractures, subsequently treated while skillfully ignoring stable posterior wall fracture according to our criteria. Intergroup comparison of radiologic and clinical outcomes and multiple linear regression for predictors of clinical outcomes were analyzed. Results No significant intergroup difference in quality of reduction, post-traumatic osteoarthritis grade, or clinical outcome was noted. Poor post-traumatic osteoarthritis grade and poor quality of reduction of both acetabular columns were significant predictors of clinical outcomes in patients with both-column acetabular fractures. Whether posterior wall fracture was associated and skillfully ignored was unrelated to clinical outcomes. Discussion Posterior wall fractures associated with both-column acetabular fractures can be successfully ignored if the posterior wall fragment is adequately attached to the acetabulum through the labrocapsular complex of the hip joint, and the hip-joint-congruency in the presence of Level of proof III, prognostic.

Splenic abscess occurs very rarely in healthy children. Although typhoid fever was the leading cause of splenic abscess in the pre-antibiotic era, Salmonella spp. remain to be the major pathogens causing splenic abscess, with an increasing worldwide frequency of splenic abscess due to non-typhoidal Salmonella infection. Here, we report the case of a 12-year-old boy, who was presumably diagnosed with acute gastroenteritis on admission and eventually diagnosed with a large splenic abscess (maximum diameter, 14.5 cm) caused by non-typhoidal Salmonella. Although splenectomy has been considered in cases of large splenic abscesses, the patient was treated with antibiotics and ultrasonography-guided percutaneous drainage. A detailed physical examination and appropriate imaging studies are necessary for the early diagnosis of extra-intestinal complications of non-typhoidal Salmonella enteritis. For treatment, percutaneous drainage, rather than splenectomy, can be used in large splenic abscesses.

Background This study compared the rates of plain radiographs and computed tomography (CT) for detecting lateral hinge fractures and to evaluate factors affecting lateral hinge fractures in patients following medial opening-wedge high tibial osteotomy (MOWHTO). Methods This prospective study included 59 patients (65 knees) undergoing MOWHTO for primary medial compartment osteoarthritis with a 2-year follow-up between 2013 and 2016. Clinical and radiographic evaluations were performed using Knee Society Score and Western Ontario and McMaster Universities Arthritis Index, and we calculated the hip-knee-ankle angle, weight-bearing line ratio, lateral distal femoral angle, medial proximal tibial angle, posterior tibial slope, osteotomy gap height, and osteotomy gap filling rate. Immediate plain radiographs and CT were used to detect lateral hinge fractures according to Takeuchi’s method. Results Among 65 knees, the incidence of lateral hinge fractures was 13.8% (Type I: 7, Type II: 2). Only 6 knee fractures (9.2%) were detected on postoperative plain radiographs, including 5 Type I fractures and 1 Type II fracture. An additional 3 knees (4.6%) were detected on postoperative CT scans, including 2 Type I fractures and 1 Type II fracture. Furthermore, osteotomy gap height (adjusted odds ratio = 1.831, P = .016) was the only predictor of lateral hinge fractures. Conclusion The incidence of lateral hinge fractures after MOWHTO was 13.8%. CT (13.8%) afforded higher detection rates for lateral hinge fractures than did plain radiographs (9.2%) despite a marginal difference with uncertain significance. Osteotomy gap height was the only predictor of lateral hinge fractures. Level of Evidence Prospective cohort study (Level II).

Enterococci are a common cause of bacteremia in immunocompromised patients. Although the increase of vancomycin-resistant enterococci (VRE) makes appropriate antibiotic therapy difficult, clinical characteristics of enterococcal bacteremia and the impact of VRE infection on outcomes have rarely been reported in immunocompromised children. We enrolled children and adolescents (

The source apportionment of volatile organic compounds (VOCs) was examined using receptor models (positive matrix factorization and chemical mass balance) and a chemical transport model (CTM). The receptor model-based analysis was performed using the datasets collected from four different sites from the megacity of Seoul during the years 2013-2015. The contributions of VOC emission sources to ozone (O3) and PM2.5 concentrations and the subsequent health effects in the study area were also assessed during a photochemically active period (June 2015) using a three-dimensional CTM, Community Multi-scale Air Quality (CMAQ), and the Environmental Benefits Mapping and Analysis Program (BenMAP). The solvent use and the on-road mobile emission sources were found to exert dominant controls on the VOC levels observed in the target city. VOCs transported from regions outside of Seoul accounted for a significant proportion (up to approximately 35%) of ambient VOC levels during the study period. The solvent use accounted for 3.4% of the ambient O3 concentrations during the day (daily mean of 2.6%) and made insignificant contributions to PM2.5 (

Long-term trends in global sea spray aerosol (SSA) emissions and dimethyl sulfide (DMS) fluxes from sea to air during the recent global warming hiatus (2000–2015) were analyzed using satellite observations and modelling data. The SSA emissions were estimated using a widely used whitecap method with sea surface temperature (SST) dependence. In addition, sea-to-air DMS fluxes were also used to quantify the secondary contributions of DMS through its sequential oxidation and gas-to-particle conversion. Aerosol optical depth (AOD) was estimated by an aerosol optical model using the number concentration of SSA and non-sea-salt sulfate from DMS. The estimated AOD, which was derived from the SSA and DMS emitted from the sea surface, was compared with satellite-derived AOD to quantify its (primary and secondary) contribution to atmospheric aerosol loading (i.e., observed AOD). Yearly global mean anomalies in DMS fluxes and AOD derived from SSA showed statistically significant downward trends during the recent global warming hiatus, whereas SSA emissions and AOD derived from DMS oxidation did not. In terms of regional trends, the decreases in SSA emissions during 2000–2015 occurred over the central Pacific Ocean, the Indian Ocean, and the Caribbean Sea, whereas upward trends in SSA emissions occurred over the tropical southeastern Pacific Ocean, the Southern Ocean, and the North Atlantic Ocean. DMS fluxes during the study period showed a clear downward trend over most regions of the global ocean. The estimates of the contributions of SSA (primary) and DMS (secondary) to atmospheric aerosol loading were 23–62% and 26–38%, respectively, with the largest primary contribution (~90%) over the Southern Ocean.

Invasive Pulmonary Aspergillosis after Recent Influenza in a Child with Acute Myeloid Leukemia Beom-Joon Kim, M.D., Seong koo Kim, M.D., Seung Beom Han, M.D., Jae Wook Lee, M.D., Ph.D., Jong-Seo Yoon, M.D., Ph.D., Nack-Gyun Chung, M.D., Ph.D., Bin Cho, M.D., Ph.D., Jin Han Kang, M.D., Ph.D. and Hack-Ki Kim, M.D., Ph.D. Department of Pediatrics, The Catholic Blood and Marrow Transplantation Center, The Vaccine Bio Research Institute, College of Medicine, The Catholic University of Korea, Seoul, Korea

Recently, the incidence of pertussis has been increasing; however, reports on mixed infection of pertussis with other respiratory pathogens are rare in highly immunized populations. We report the case of a 10-year-old girl who presented with cough, post-tussive emesis, and fever. She was subsequently diagnosed with bronchopneumonia. Although she had received five doses of diphtheria-tetanus-acellular pertussis vaccine, polymerase chain reaction of her nasopharyngeal aspirate confirmed Bordetella pertussis infection. In addition, serologic testing for Mycoplasma pneumoniae was also positive. The patient was treated with roxithromycin without any complications. This is the first report of mixed B. pertussis and M. pneumoniae infection in Korea. To avoid under-diagnosis, pertussis should be considered in patients with chronic cough even when other respiratory pathogens have been documented.

Rotavirus (RV) is one of the most important viral etiologic agents of acute gastroenteritis (AGE) in children. Although effective RV vaccines (RVVs) are now used worldwide, novel genotypes and outbreaks resulting from rare genotype combinations have emerged. This study documented RV genotypes in a Korean population of children with AGE 5 yr after the introduction of RVV and assessed potential genotype differences based on vaccination status or vaccine type. Children less than 5-yr-old diagnosed with AGE between October 2012 and September 2013 admitted to 9 medical institutions from 8 provinces in Korea were prospectively enrolled. Stool samples were tested for RV by enzyme immunoassay and genotyped by multiplex reverse-transcription polymerase chain reaction. In 346 patients, 114 (32.9%) were RV-positive. Among them, 87 (76.3%) patients were infected with RV alone. Eighty-six of 114 RV-positive stool samples were successfully genotyped, and their combinations of genotypes were G1P[8] (36, 41.9%), G2P[4] (12, 14.0%), and G3P[8] (6, 7.0%). RV was detected in 27.8% of patients in the vaccinated group and 39.8% in the unvaccinated group (P=0.035). Vaccination history was available for 67 of 86 cases with successfully genotyped RV-positive stool samples; RotaTeq (20, 29.9%), Rotarix (7, 10.4%), unvaccinated (40, 59.7%). The incidence of RV AGE is lower in the RV-vaccinated group compared to the unvaccinated group with no evidence of substitution with unusual genotype combinations. Graphical Abstract

Open-wedge high tibial osteotomy (HTO) cannot always accurately correct limb alignment, resulting in under- or over-correction. This study assessed the relationship between soft tissue laxity of the knee joint and alignment correction in open-wedge HTO. This prospective study involved 85 patients (86 knees) undergoing open-wedge HTO for primary medial osteoarthritis. The mechanical axis (MA), weight-bearing line (WBL) ratio, and joint line convergence angle (JLCA) were measured on radiographs preoperatively and after 6 months, and the differences between the pre- and post-surgery values were calculated. Post-operative WBL ratios of 57–67 % were classified as acceptable correction. WBL ratios 67 % were classified as under- and over-corrections, respectively. Preoperative JLCA correlated positively with differences in MA (r = 0.358, P = 0.001) and WBL ratio (P = 0.003). Difference in JLCA showed a stronger correlation than preoperative JLCA with differences in MA (P

Purpose We aimed to compare posterior cruciate ligament (PCL) tibial tunnel location after tibial guide insertion medial (between the PCL remnant and the medial femoral condyle) and lateral (between the PCL remnant and the anterior cruciate ligament) to the PCL stump as determined by in vivo 3-dimensional computed tomography (3D-CT). Methods Tibial tunnel aperture location was analyzed by immediate postoperative in vivo CT in 66 patients who underwent single-bundle PCL reconstruction, 31 by over-the-PCL and 35 by under-the-PCL tibial guide insertion techniques. Tibial tunnel positions were measured in the medial to lateral and proximal to distal directions of the posterior proximal tibia. Results The center of the tibial tunnel aperture was located more laterally (by 2.7 mm) in the over-the-PCL group than in the under-the-PCL group ( P = .040) and by a relative percentage (absolute value/tibial width) of 3.2% ( P = .031). Tibial tunnel positions in the proximal to distal direction, determined by absolute value and relative percentage, were similar in the 2 groups. Conclusions Tibial tunnel apertures were located more laterally after lateral-to-the-PCL tibial guide insertion than after medial-to-the-PCL tibial guide insertion. There was, however, no significant difference between these techniques in distance from the joint line to the tibial tunnel aperture. Insertion lateral to the PCL stump may result in better placement of the PCL in its anatomic footprint. Level of Evidence Level III, retrospective comparative study.

Purpose Active reduced dose tetanus-diphtheria-acellular pertussis (Tdap) vaccination for adolescents and adults is necessary because waning immunity after primary diphtheria-tetanus-pertussis vaccination is related to the recent emergence of pertussis. This study was conducted to compare the immunogenicity and protection efficacy against Bordetella pertussis between a new GCC Tdap vaccine and a commercially available Tdap vaccine in a murine model. Materials and methods BALB/c mice were immunized with two doses of diphtheria-tetanus-acellular pertussis (DTaP) vaccine for priming and a subsequent Tdap booster vaccination. According to the type of booster vaccine, mice were divided into four groups: commercially available Tdap vaccine in group 1 and GCC Tdap vaccines of different combinations of pertussis antigens in groups 2 to 4. Humoral and cell-mediated immune responses and protection efficacy using a murine intranasal challenge model after booster vaccination were compared among the four groups. Results Every group showed significant increases in antibody titers against pertussis antigens such as pertussis toxin, filamentous hemagglutinin, and pertactin after booster vaccination. Spleen cells showed both Th1 and Th2 cell-mediated immune responses stimulated by pertussis antigens in all groups without any significant difference. In the intranasal B. pertussis infection model, bacteria were eradicated in all groups five days after challenge infection. Conclusion This preliminary study did not show significantly different immunogenicity or protection efficacy of the new GCC Tdap vaccines compared to the commercially available Tdap vaccine, although a more extensive study is necessary to assess the differing efficacies of the new GCC Tdap vaccines.

Hemorrhagic cystitis is a common stem cell transplantation-related complication. The incidence of early-onset hemorrhagic cystitis, which is related to the pretransplant conditioning regimen, has decreased with the concomitant use of mesna and hyperhydration. However, late-onset hemorrhagic cystitis, which is usually caused by the BK virus, continues to develop. Although the BK virus is the most common pathogenic microorganism of poststem cell transplantation late-onset hemorrhagic cystitis, pediatricians outside the hemato-oncology and nephrology specialties tend to be unfamiliar with hemorrhagic cystitis and the BK virus. Moreover, no standard guidelines for the early diagnosis and treatment of BK virus-associated hemorrhagic cystitis after stem cell transplantation have been established. Here, we briefly introduce poststem cell transplantation BK virus-associated hemorrhagic cystitis.

We prospectively analyzed 83 patients who underwent ceramic-on-ceramic THA using preassembled (n = 22) or modular acetabular components (n = 61) between June 2010 and June 2012. There were no significant differences in mean postoperative radiographic outcomes, functional outcomes, or complications between the two groups. Both groups showed satisfactory performance at the 2 year follow up. Only the gender of the patients was significantly different between the two groups. Half of the women had smaller acetabular diameters accommodating a cup size of only 48-50-mm. Although a preassembled cup with a 36-mm ceramic liner is proven to be safe in the short term, future research should focus on evaluating the long-term risks.

The objective of this study was to analyze the prevalence and causes of early re-operation after hip replacement surgery using short bone-preserving stems in a large multicentre series. Specifically, we evaluated the clinical features of periprosthetic fractures occurring around short stems. A total of 897 patients (1089 hips) who underwent primary total hip arthroplasty or bipolar hemiarthroplasty from January 2011 to February 2015 using short bone-preserving femoral stems were recruited. Mean patient age was 57.4 years (range, 18–97 years), with a male ratio of 49.7% (541/1089). Re-operation for any reason within two years was used as an endpoint. The incidence and clinical characteristics of the periprosthetic femoral fractures were also recorded. Mean follow-up period was 5.1 years (range, 2–7.9 years). Early re-operation for any reason was identified in 16 (1.5%) of 1089 hips. The main reason for re-operation was periprosthetic femoral fracture, which accounted for eight (50%) of the 16 re-operations. The overall incidence of periprosthetic femoral fracture at two years was 1.1% (12/1089). According to the Vancouver classification, two fractures were AG type and the other ten were B1 type. Advanced age, higher American Society of Anesthesiologist grade, femur morphology of Dorr type C, and the use of a calcar-loading stem increased the risk for periprosthetic femoral fracture. Periprosthetic femoral fracture was the major reason for re-operation after hip replacement surgery using short bone-preserving stems accounting for 50% (8/16) of re-operations two years post-operatively, but did not seem to deteriorate survivorship of implanted prostheses.

The treatment options for nonunions of infraisthmal femoral shaft fractures after internal fixation are controversial. Methods such as exchanging an existing nail with a nail of a larger size, dynamization, removal of the nail followed by plating, and bone grafting have all been reported. Among those options, exchange nailing seems to be the most popular choice. In this study, a Poller screw, or an additional interlocking screw, was used in conjunction with exchange intramedullary nailing. The purpose of this study was to evaluate the effectiveness of treating femoral shaft nonunions using insertion of a Poller screw or an additional interlocking screw in conjunction with intramedullary nail fixation. This study included 18 patients who presented with nonunion of femur shaft fractures after internal fixation at the infraisthmal level. These patients included 13 men and 5 women, with a mean age of 46.8 years (range 15–78 years). The mean postsurgical period of nonunion was 7.8 months (range 6–12 months). The patients were classified into two groups: the atrophic nonunion group and the hypertrophic nonunion group. In all patients, nailing was enhanced with a Poller screw or additional interlocking screws. All patients were followed up with plain film examinations and were assessed for their functional recovery status to determine the osseous union conditions. All 18 patients achieved postoperative bony union after a mean time of 7.5 months (range 3–12 months), and all patients were able to walk with full weight-bearing and without pain within 3 months. There were no significant complications, such as broken hardware, implant back-outs, axial or rotational malalignments, or deep infections. Poller screws and additional interlocking screws, along with intramedullary nailing exchange, may be an effective and reliable alternative for treating infraisthmal femoral shaft nonunions.

Although acyclovir prophylaxis against varicella zoster virus (VZV) infection for ≥1 year is recommended after allogeneic hematopoietic cell transplantation (HCT), the emergence of acyclovir-resistant viruses and adverse drug effects cannot be ignored. We investigated the cumulative incidence of VZV infection after allogeneic HCT in children receiving a shorter duration of acyclovir prophylaxis than recommended and evaluated the appropriateness of the short duration of acyclovir prophylaxis. Medical records of 217 children who received allogeneic HCT were retrospectively reviewed until a median of 25 months (range = 1–59 months) after HCT. Acyclovir prophylaxis was given for a median of 9 weeks (range = 3–24 weeks) after HCT. VZV infection was diagnosed in 33 (15.2%) children at a median time of 5 months (range = 2–41 months) after HCT. The 1-year and 2-year cumulative incidences of VZV infection after allogeneic HCT were 11.2% and 15.5%, respectively. These incidences were between the previously reported 1-year incidence of 25% to 30% in patients not receiving prophylaxis and 1-year incidence of 4% to 5% in patients receiving ≥1 year duration of prophylaxis. Male sex and older age were significantly associated with VZV infection after allogeneic HCT. Only 1 chickenpox patient experienced severe complications because of VZV infection, and there were no deaths attributable to VZV infection. In conclusion, a shorter duration of acyclovir prophylaxis may be appropriate for children receiving allogeneic HCT, based on the rare occurrence of severe complications because of VZV infection and the expected discomfort because of daily oral medication for a long time.

Extensive bone bleeding and an uncomfortable hematoma can develop due to the opening gap and space during a medial open high tibial osteotomy (HTO). Tranexamic acid (TXA) has been used in various orthopaedic surgeries to reduce bleeding and wound complications. However, no study has investigated the effect of TXA during HTO. Therefore, the purpose of this study is to evaluate the efficacy of TXA in reducing postoperative blood loss in patients undergoing HTO. The hypothesis is that topical TXA administration will reduce postoperative bleeding in patients undergoing medial opening HTO. Topical TXA (2 g in 20 mL saline) was administered at the osteotomy site in patients (n = 15) who underwent medial open HTO from November 2015 to March 2016. Patients (n = 15) who underwent medial open wedge HTO by the same surgeon from October 2014 to October 2015 were enrolled as a control group for comparison. Drainage volumes on postoperative days (PODs) 1, 2, and 3 as well as hemoglobin (Hb) level on PODs 1, 6, and 13 were measured and compared. Mean total postoperative drainage volume was 246 mL in the TXA group and 377 mL in the control group. Mean drainage volume on POD 1 was 138 mL in the TXA group and 277 mL in the control group (p 0.05). An extensive hematoma requiring additional surgery developed in one case in the control group. No wound complications were detected in the TXA group. Topical TXA was effective for reducing postoperative bleeding after medial open HTO. The level of evidence of the study is Level 3.

Background Although the proportion of Pseudomonas aeruginosa infections has reduced after the introduction of antibiotics with anti-pseudomonal effects, P. aeruginosa bacteremia still causes high mortality in immunocompromised patients. This study determined the clinical characteristics and outcomes of P. aeruginosa bacteremia and the antibiotic susceptibilities of strains isolated from febrile neutropenic patients. Methods Thirty-one febrile neutropenic children and adolescents with underlying hematologic/oncologic disorders diagnosed with P. aeruginosa bacteremia between 2011 and 2016 were enrolled in the study. Their medical records were retrospectively reviewed to evaluate the demographic and clinical characteristics. Antibiotic susceptibility rates of the isolated P. aeruginosa to eight antibiotic categories (anti-pseudomonal penicillin, anti-pseudomonal penicillin and β-lactamase inhibitor combination, anti-pseudomonal cephalosporin, monobactam, carbapenem, aminoglycoside, fluoroquinolone, and colistin) were also determined. Among the investigated factors, risk factors for mortality and infections by a multidrug-resistance (MDR) strain were determined. Results Thirty-six episodes of P. aeruginosa bacteremia were identified. The mean age of the enrolled patients was 9.5 ± 5.4 years, and 26 (72.2%) episodes occurred in boys. Acute myeloid leukemia (41.7%) and acute lymphoblastic leukemia (33.3%) were the most common underlying disorders. The 30-day mortality was 38.9%, and 36.1% of the episodes were caused by MDR strains. The deceased patients were more likely to experience breakthrough infection (P = 0.036) and bacteremia (P = 0.005) due to MDR strains when compared with the patients who survived. The survived patients more likely received appropriate empirical antibiotic therapy (P = 0.024) and anti-pseudomonal β-lactam and aminoglycoside combination therapy (P = 0.039) compared with the deceased patients. The antibiotic susceptibility rates of the isolated P. aeruginosa strains were as follows: piperacillin/tazobactam, 67.6%; meropenem, 72.2%; and amikacin, 100%. Conclusions Mortality due to P. aeruginosa bacteremia remained at 38.9% in this study, and more than one-third of the isolated strains were MDR. In this context, empirical antibiotic combination therapy to expand the antibiotic spectrum may be a strategy to reduce mortality due to P. aeruginosa bacteremia in febrile neutropenic patients.

Background. It is unclear whether computer navigation can improve the accuracy and reliability of targeted lower limb alignment correction following open-wedge high tibial osteotomy (HTO). This meta-analysis was designed to compare the accuracy and reliability of limb alignment correction between computer navigated and conventional open-wedge HTOs. Methods. Studies that compared postoperative coronal alignment, including mechanical axis (MA) and weight bearing line (WBL) ratio, outliers of alignment correction, and change in tibial posterior slope, following open-wedge HTO performed using computer navigated and conventional methods were included. Results. Ten studies were included in the meta-analysis. The MA (0.93°; 95% confidence interval [CI]: 0.45–1.41°; P<0.001) and WBL ratio (1.5%; 95% CI: 0.03–2.98%; P=0.048) were significantly greater for computer navigated HTO than for conventional HTO. Outliers of alignment correction after surgery were significantly lower in patients who underwent computer navigated HTO than in those who underwent conventional HTO (odds ratio: 0.25; 95% CI: 0.08–0.79; P=0.02). Changes in posterior tibial slope from before to after surgery, however, were similar for the two approaches. Conclusion. Computer navigated HTO resulted in slightly more valgus postoperative alignment and effectively reduced outliers of alignment correction but had no effect on change in posterior tibial slope when compared with conventional HTO.

Purpose: The purpose of this study was to evaluate the biomechanical properties of a new anatomical locking metal block plate by comparing the initial biomechanical stability of three different fixation constructs for open wedge high tibial osteotomy (HTO). Materials and Methods: Sawbones composite tibiae were used to make a 10-mm opening osteotomy model with uniplane technique. The osteotomy was secured with three different types of plates: Group I, new osteotomy plate without a metal block (n=5); Group II, new osteotomy plate with a 10mm metal block (n=5); and Group III, two short metal block plates (n=5). Single load to failure test and staircase load-controlled cyclical failure test were performed. In the single load to failure test, the yield load, maximum failure load, and the displacement of the osteotomy gap were measured. In the staircase cyclical load to failure test, the total number of cycles to failure was recorded. Failure modes were observed during both single and cyclic load tests. Results: Group II showed the highest yield and ultimate loads (1829±319 N, 3493±1250 N) compared to Group I (1512±157 N, 2422±769 N) and Group III (1369±378 N, 2157±210 N, p

SUMMARYWe conducted a cross-sectional seroepidemiological study in 2012–2013 to determine the seroprevalence of varicella-zoster virus (VZV) in adolescents and adults living in Korea, where varicella vaccination has been recommended universally at age 12–15 months since 2005. Residual serum samples were collected from 1196 healthy adults and adolescents aged ⩾10 years between November 2012 and March 2013. The fluorescent antibody to membrane antigen (FAMA) test and enzyme-linked immunosorbent assay (ELISA) were performed to determine the seroprevalence of VZV. The seroprevalences of VZV were compared between six age groups: 10–19, 20–29, 30–39, 40–49, 50–59, and ⩾60 years. The seroprevalence of VZV in the entire study cohort was 99·1% according to the FAMA test and 93·1% as determined by ELISA. The seroprevalences of the six age groups were as follows: 96·0%, 99·5%, 99·5%, 99·5%, 100%, and 100%, respectively, by the FAMA test, and 83·3%, 93·0%, 93·0%, 97·5%, 94·5%, and 97·5%, respectively, by ELISA. Seroprevalence increased significantly with age (P< 0·001); moreover, the seroprevalence in subjects aged 10–19 years was significantly lower than in other age groups (P< 0·001), as measured by both the FAMA test and ELISA. Thus, strategies to increase protective immunity against VZV in teenagers are necessary.

The present study was conducted to investigate Epstein-Barr virus (EBV) reactivation after hematopoietic cell transplantation (HCT) in Korean children living in an area of a high seroprevalence against EBV and to determine the impact of recipient age on EBV reactivation. Medical records of 248 children and adolescents who had received allogeneic HCT were retrospectively reviewed. The trends of EBV reactivation and post-transplant lymphoproliferative disorders (PTLDs) were evaluated and compared between younger (≤10 years old) and older (11-20 years old) groups. EBV reactivation occurred in 177 cases (71.4 %) and high-level EBV reactivation, defined as a virus DNA titer of 300,000 copies/mL or higher, occurred in 21 cases (8.5 %). PTLD was diagnosed in five cases (2.0 %), and one of these patients died. The EBV reactivation rate was not significantly different between the two age groups; however, high-level reactivation and PTLD were more significantly frequent in the older than in the younger group (P = 0.030 and P = 0.026, respectively). In conclusion, older children and adolescents are more likely to experience high-level EBV reactivation and PTLDs, and higher EBV DNA titers than those previously reported may be a predictor of PTLD in areas with a high seroprevalence against EBV.

This seroepidemiologic study was performed to evaluate the immune status against tetanus in Korean adolescents and adults and to provide evidence to develop strategies for tetanus prevention. Between July 2012 and December 2012, serum samples were collected from adults and adolescents 11 years of age and older, and serum anti-tetanus IgG titers were determined using a commercial ELISA kit. Subjects were divided into six age groups: 11-20 years, 21-30 years, 31-40 years, 41-50 years, 51-60 years, and ≥61 years. The mean anti-tetanus IgG titers and tetanus seroprevalence of the age groups were compared. A total of 1193 adults and adolescents were enrolled. Mean anti-tetanus IgG titer and tetanus seroprevalence of all subjects were 1.20 ± 3.58 IU/mL and 56.4%, respectively. The mean anti-tetanus IgG titer decreased with an increase in age (p0.001). Tetanus seroprevalence increased from 92.0% in the 11-20 year age group to 95.7% in the 21-30 year age group, and then decreased with a further increase in age (p0.001). These results reflected an appropriate Td booster vaccine coverage at 11-12 years of age. However, the tetanus seroprevalence of adults older than 41 years was as low as the levels in previous studies: therefore, adults should be more encouraged to acquire decennial Td booster vaccinations recommended by the National Immunization Program.

The graft-healing potential of mesenchymal stromal cells (MSCs) derived from the remnants of ruptured anterior cruciate ligaments (ACLs) after ACL reconstruction may depend on the chronicity of the injury. The aim of this study was to assess the quantitative and phenotypic differences between MSCs isolated from ACL remnants in patients with (sub)acute and chronic tearing.Torn ACL remnants were harvested during ACL reconstruction from 41 patients, 24 with (sub)acute ACL (6 months from injury to surgery) and 17 with chronic ACL (time interval6 months) tears. MSCs isolated from these samples were assessed for quantitative and phenotypic differences, and the correlation between the proportion of MSCs and the chronicity of ACL tear was evaluated.At passage 0, the mean proportion of MSCs (CD34(-), CD44(+), CD90(+) and CD105(+)) was higher in (sub)acute than in chronic ACL tear samples (20.69% ± 7.82% versus 9.85% ± 8.01%, P 0.001). At passages 1 and 2, however, MSC proportions did not differ significantly in the two groups. Time interval showed a negative correlation with MSC proportion only at passage 0 (r = -0.505, P 0.001). The optimal cutoff value for time from injury to surgery yielding 10% freshly isolated ACL-MSCs, a percentage expected to have low tissue healing potential, was 23.5 months.The proportion of freshly isolated MSCs was higher in samples from patients with (sub)acute tearing than in chronic ACL tearing and negatively correlated with the time interval between trauma and surgery.

Kikuchi-Fujimoto disease (KFD) is characterized by self-limiting regional lymphadenopathy with prolonged fever. Although the reported recurrence rate of KFD is known to be 3–4 %, this rate appears to be higher in our clinical experience, and rates up to 38.5 % have been previously reported. In this retrospective study, we reviewed medical records of children with pathologically confirmed KFD to investigate the factors associated with recurrent KFD. Enrolled children were divided into two groups according to the recurrence of KFD, and clinical and laboratory factors were compared between the two groups. The recurrence of KFD was determined based not on repeated pathologic confirmation but on the presence of clinical febrile lymphadenopathy. A total of 33 children with KFD, 26 boys (78.8 %) and 7 girls (21.2 %), with a median age of 12 years (9 months to 19 years), were enrolled. Thirty-one children (93.9 %) complained of fever, and most of the children (90.9 %) complained of cervical lymphadenopathy. Neutropenia (

This study was conducted to evaluate age-specific seroprevalence of pertussis in Korea and to formulate a strategy to prevent and reduce the incidence of pertussis. Residual serum samples of healthy adolescents and adults 11 yr of age or older were collected between July 2012 and December 2012, and anti-pertussis toxin (PT) IgG titers were measured using a commercial ELISA kit. We compared the mean anti-PT IgG titers and seroprevalence of pertussis of the six age groups: 11-20, 21-30, 31-40, 41-50, 51-60, and ≥ 61 yr. A total of 1,192 subjects were enrolled. The mean anti-PT IgG titer and pertussis seroprevalence were 35.53 ± 62.91 EU/mL and 41.4%, respectively. The mean anti-PT IgG titers and seroprevalence were not significantly different between the age groups. However, the seroprevalence in individuals 51 yr of age or older was significantly higher than in individuals younger than 51 yr (46.5% vs 39.1%, P = 0.017). Based on these results, a new pertussis prevention strategy is necessary for older adults. Graphical Abstract Keywords: Pertussis Vaccine, Prevalence, Korea, Vaccination INTRODUCTION The incidence of pertussis decreased with the introduction of the diphtheria-tetanus-whole cell pertussis (DTwP) vaccination in children around the world (1), and a decrease in pertussis was also observed in Korea where the DTwP vaccination has been universally recommended for infants and children since 1954 (2). However, pertussis began to rise in the 1990s in Europe and North America, especially in adolescents (1, 3, 4, 5), and it has been also observed since the 2000s in Korea (2). The increased incidence of pertussis was assumed to be caused by a waning vaccine effect after previous vaccinations, a decreased boosting effect by natural pertussis infections in a community, the emergence of mutated Bordetella pertussis species that differ from the vaccine strain, and improved diagnostic modalities (3, 4, 5, 6, 7). In the United States, since 2006, Tdap booster vaccinations at adolescence have been recommended to control the increasing pertussis incidence based on cost-effectiveness studies (8, 9, 10). An adolescent Tdap booster vaccination at 11-12 yr of age was also introduced in 2009 in Korea because the incidence of pertussis began to rise in the 2000s (2). Pertussis in adolescents and adults often presents with atypical manifestations, such as asymptomatic infections and a chronic cough, rather than typical pertussis symptoms, and because of this, the actual infection rates may be higher than the incidence and prevalence based on clinical diagnosis (11, 12, 13). Therefore, repeated seroepidemiological studies are necessary to understand pertussis epidemiology and seroprevalence in communities. We conducted this seroepidemiological study to evaluate the current status and periodic changes of pertussis prevalence in Korea after 2002 and 2008 (14).

Background Neonatal herpes simplex virus (NHSV) infection is rare but can cause a severe disease, even death. However, data on NHSV are limited in Asia. The aim of this study was to estimate the number of NHSV infection and evaluate the characteristics of NHSV infection in Korea where seroprevalence of HSV infection in child-bearing age women is not well known. Methods This is the first multicenter retrospective study in 12 university hospitals in Korea. From January 2008 to December 2017, neonates ≤ 28-day old with confirmed HSV infection were identified and a chart review was performed. Results Among 12 medical centers, 16 patients were identified in six centers. Eight (50%) patients were male and median age at admission was 11.1 days (range, 0–28 days). Ten (63%) patients were positive for HSV 1 and six (37%) patients were HSV 2 positive. Four (25%) patients were classified as disseminated HSV. Eleven (69%) patients were diagnosed as central nervous system (CNS) disease. One (6%) patient had skin, eye, and/or mouth (SEM) disease. All the patients received intravenous acyclovir and median treatment duration was 19 days (range 3–68 days). Five (35%) patients received additional suppressive therapy and median treatment duration was 131.4 days. Four patients (25%) developed seizure (one in disseminated and three in CNS disease) and two of them recovered without neurologic complications. Two (12.5%) patients with disseminated disease died within 30 days from the diagnosis and one of them had a maternal history of previous genital herpetic lesion. There was no mention on maternal history of genital herpes in 10 (63%) patients in the medical records. Conclusion Although not common, NHSV infection occurs in Korean babies with high 30-day mortality rate of 12.5%. Increased awareness is warranted among Korean pediatricians to take a thorough maternal history of genital herpes infection. Disclosures All Authors: Korean Society of Pediatric Infectious Diseases: Member, Research grant.

Several approved inactivated hepatitis A (HA) vaccines are available in Korea. These have been shown to be immunogenic and safe in European children; however, their immunogenicity and safety have not been investigated among Korean children. We aimed to compare the immunogenicity and safety o

Purpose Although the DTaP and Tdap vaccines used to prevent pertussis have been used for a long time, there is no standard method for measuring pertussis antigens. Therefore, this preliminary study was conducted to develop an enzyme-linked immunosorbent assay method using an animal model for measuring antibodies against pertussis toxin, the most important pertussis pathogenic antigen, in the sera of vaccinated mice. Materials and Methods Bordetella pertussis Tohama phase I was cultured for 24–30 hours, and then pertussis toxin was purified from the culture medium by chromatography. Purified pertussis toxin was diluted in phosphate-buffered saline-coating buffer, and 100 µL of diluted pertussis toxin was added to each well and reacted at room temperature for 4 hours. Positive serum was diluted to 1/1,250–1/80,000 and negative serum was diluted to 1/50 to determine the coating concentration with the optimal signal/noise ratio. Optimal test conditions were confirmed from the dilution factors of the secondary antibody and streptavidin horseradish peroxidase (SA-HRP). Results Optimal conditions were as follows: 4 µg/mL for coating antigen; 1/40,000 for secondary antibody; and 1/1,000 for the SA-HRP dilution factor. Comparison of the sera obtained from mice treated with a developing vaccine and commercial vaccine with National Institute for Biological Standard and Control standard serum under the established conditions showed the following results: 1,300.62, 534.94, and 34.85, respectively. Conclusion The method developed in this study is suitable for measuring anti-pertussis toxin antibodies and may be applicable for clinical sample analysis or indirect diagnosis of pertussis.

This retrospective study was performed to determine the seroprevalence of hepatitis A virus (HAV) in children and adolescents with hematologic malignancies after the completion of chemotherapy and hematopoietic cell transplantation (HCT). Of 97 enrolled patients, 60 (61.9%) were seropositive for HAV. The seroprevalences in patients undergoing chemotherapy and HCT were 60.3% (41/68) and 65.5% (19/29), respectively (P = 0.628). No significant factors associated with seropositivity for HAV after chemotherapy and HCT were identified. Anti-HAV tests and HAV re-vaccinations can be considered in children and adolescents with underlying hematologic malignancies after chemotherapy and HCT based on the anti-HAV results.

A retrospective analysis of 63 primary total hip arthroplasty cases was done using repeated computed tomography scans to evaluate the pelvic osteolytic lesions in early stage. The progression rate of osteolysis of hips with small osteolytic volume less than 766.97 mm(3) in initial CT was 85.82 mm(3)/year, and that of hips with osteolysis more than 766.97 mm(3) was 456.3 mm(3)/year (P < 0.001). Younger patients less than 52 years old with good Harris Hip Scores (more than 80) frequently showed much faster progression in volume of osteolytic lesions. The rate of osteolysis was accelerated when the amount of osteolysis reached a certain threshold volume in active young patients in a cascade manner even in early stage.

We evaluated 106 knees that underwent primary total knee arthroplasty (TKA) with the navigation-assisted gap balancing technique using an e.-motion cruciate retaining floating platform (FP) mobile-bearing prosthesis to prospectively assess the survival of the e.-motion FP system after a minimum follow-up of 4 years. There was no evidence of any complications, including dissociation or breakage of the polyethylene liner or component loosening at last follow up (5.1 ± 0.6 years). Four knees, however, required re-operation, three for distal femoral fracture, and one for infection. The estimated 5-year prosthesis survival rates without revision for any reason and for prosthesis-associated problems were 96.2% and 100%, respectively. The e.-motion floating platform, with a cruciate retaining design under navigation guidance, demonstrated excellent clinical results and 5-year survival rate.