Computational wear prediction of insert conformity and material on mobile-bearing unicompartmental knee arthroplasty.

OBJECTIVES: Unicompartmental knee arthroplasty (UKA) is an alternative to total knee arthroplasty with isolated medial or lateral compartment osteoarthritis. However, polyethylene wear can significantly reduce the lifespan of UKA. Different bearing designs and materials for UKA have been developed to change the rate of polyethylene wear. Therefore, the objective of this study is to investigate the effect of insert conformity and material on the predicted wear in mobile-bearing UKA using a previously developed computational wear method. METHODS: Two different designs were tested with the same femoral component under identical kinematic input: anatomy mimetic design (AMD) and conforming design inserts with different conformity levels. The insert materials were standard or crosslinked ultra-high-molecular-weight polyethylene (UHMWPE). We evaluated the contact pressure, contact area, wear rate, wear depth, and volumetric wear under gait cycle loading conditions. RESULTS: Conforming design inserts had the lower contact pressure and larger contact area. However, they also had the higher wear rate and volumetric wear. The improved wear performance was found with AMD inserts. In addition, the computationally predicted volumetric wear of crosslinked UHMWPE inserts was less than half that of standard UHMWPE inserts. CONCLUSION: Our results showed that increasing conformity may not be the sole predictor of wear performance; highly crosslinked mobile-bearing polyethylene inserts can also provide improvement in wear performance. These results provide improvements in design and materials to reduce wear in mobile-bearing UKA.Cite this article: Bone Joint Res 2019;8:563-569.

Revision adenoidectomy in children: a meta-analysis.

BACKGROUND: To estimate the rate of revision surgery after previous adenoidectomy in children and to compare the rate of revision adenoidectomy in children with different conditions and by using different surgical techniques. METHODOLOGY: The study protocol was registered on PROSPERO (CRD42018107877). Two authors independently searched databases, specifically PubMed, MEDLINE, EMBASE, and the Cochrane Review database. The keywords used were "adenoids","adenoidectomy","reoperation","revision"and "regrowth". The revision rate was pooled using a random-effect model. Subgroup analyses were conducted for children based on different settings, countries, risks of bias, and surgical techniques. RESULTS: A total 16 studies with 95 727 children were analyzed (mean age: 4.69 (1.62) years; 60% boys; sample size: 5983 patients). Five studies had a low risk of bias, 10 studies had a moderate risk of bias, and one study had a high risk of bias. The rate of revision adenoidectomy was 1.9%. Ages at initial surgery and follow-up were not significantly associated with revision surgeries. The revision rate was not significantly different in children receiving surgeries in different settings (single center vs multicenter vs population-based, country (non-United States vs United States, and risk of bias. Moreover, surgical techniques, such as curettage, suction cautery, microdebridement, and coblation did not significantly affect revision rates in children who received adenoidectomy. CONCLUSIONS: Revision surgery was undertaken with a frequency of 1.9% in children who underwent adenoidectomy. A lack of strong evidence exists to correlate surgical techniques with revision rate in pediatric adenoidectomy.

Influence of tibiofemoral congruency design on the wear of patient-specific unicompartmental knee arthroplasty using finite element analysis.

OBJECTIVES: Unicompartmental knee arthroplasty (UKA) is an alternative to total knee arthroplasty for patients who require treatment of single-compartment osteoarthritis, especially for young patients. To satisfy this requirement, new patient-specific prosthetic designs have been introduced. The patient-specific UKA is designed on the basis of data from preoperative medical images. In general, knee implant design with increased conformity has been developed to provide lower contact stress and reduced wear on the tibial insert compared with flat knee designs. The different tibiofemoral conformity may provide designers the opportunity to address both wear and kinematic design goals simultaneously. The aim of this study was to evaluate wear prediction with respect to tibiofemoral conformity design in patient-specific UKA under gait loading conditions by using a previously validated computational wear method. METHODS: Three designs with different conformities were developed with the same femoral component: a flat design normally used in fixed-bearing UKA, a tibia plateau anatomy mimetic (AM) design, and an increased conforming design. We investigated the kinematics, contact stress, contact area, wear rate, and volumetric wear of the three different tibial insert designs. RESULTS: Conforming increased design showed a lower contact stress and increased contact area. In addition, increased conformity resulted in a reduction of the wear rate and volumetric wear. However, the increased conformity design showed limited kinematics. CONCLUSION: Our results indicated that increased conformity provided improvements in wear but resulted in limited kinematics. Therefore, increased conformity should be avoided in fixed-bearing patient-specific UKA design. We recommend a flat or plateau AM tibial insert design in patient-specific UKA.Cite this article: Y-G. Koh, K-M. Park, H-Y. Lee, K-T. Kang. Influence of tibiofemoral congruency design on the wear of patient-specific unicompartmental knee arthroplasty using finite element analysis. Bone Joint Res 2019;8:156-164. DOI: 10.1302/2046-3758.83.BJR-2018-0193.R1.

A computational simulation study to determine the biomechanical influence of posterior condylar offset and tibial slope in cruciate retaining total knee arthroplasty.

OBJECTIVES: Posterior condylar offset (PCO) and posterior tibial slope (PTS) are critical factors in total knee arthroplasty (TKA). A computational simulation was performed to evaluate the biomechanical effect of PCO and PTS on cruciate retaining TKA. METHODS: We generated a subject-specific computational model followed by the development of ± 1 mm, ± 2 mm and ± 3 mm PCO models in the posterior direction, and -3°, 0°, 3° and 6° PTS models with each of the PCO models. Using a validated finite element (FE) model, we investigated the influence of the changes in PCO and PTS on the contact stress in the patellar button and the forces on the posterior cruciate ligament (PCL), patellar tendon and quadriceps muscles under the deep knee-bend loading conditions. RESULTS: Contact stress on the patellar button increased and decreased as PCO translated to the anterior and posterior directions, respectively. In addition, contact stress on the patellar button decreased as PTS increased. These trends were consistent in the FE models with altered PCO. Higher quadriceps muscle and patellar tendon force are required as PCO translated in the anterior direction with an equivalent flexion angle. However, as PTS increased, quadriceps muscle and patellar tendon force reduced in each PCO condition. The forces exerted on the PCL increased as PCO translated to the posterior direction and decreased as PTS increased. CONCLUSION: The change in PCO alternatively provided positive and negative biomechanical effects, but it led to a reduction in a negative biomechanical effect as PTS increased.Cite this article: K-T. Kang, Y-G. Koh, J. Son, O-R. Kwon, J-S. Lee, S. K. Kwon. A computational simulation study to determine the biomechanical influence of posterior condylar offset and tibial slope in cruciate retaining total knee arthroplasty. Bone Joint Res 2018;7:69-78. DOI: 10.1302/2046-3758.71.BJR-2017-0143.R1.

Patient-specific medial unicompartmental knee arthroplasty has a greater protective effect on articular cartilage in the lateral compartment: A Finite Element Analysis.

OBJECTIVES: Patient-specific (PS) implantation surgical technology has been introduced in recent years and a gradual increase in the associated number of surgical cases has been observed. PS technology uses a patient's own geometry in designing a medical device to provide minimal bone resection with improvement in the prosthetic bone coverage. However, whether PS unicompartmental knee arthroplasty (UKA) provides a better biomechanical effect than standard off-the-shelf prostheses for UKA has not yet been determined, and still remains controversial in both biomechanical and clinical fields. Therefore, the aim of this study was to compare the biomechanical effect between PS and standard off-the-shelf prostheses for UKA. METHODS: The contact stresses on the polyethylene (PE) insert, articular cartilage and lateral meniscus were evaluated in PS and standard off-the-shelf prostheses for UKA using a validated finite element model. Gait cycle loading was applied to evaluate the biomechanical effect in the PS and standard UKAs. RESULTS: The contact stresses on the PE insert were similar for both the PS and standard UKAs. Compared with the standard UKA, the PS UKA did not show any biomechanical effect on the medial PE insert. However, the contact stresses on the articular cartilage and the meniscus in the lateral compartment following the PS UKA exhibited closer values to the healthy knee joint compared with the standard UKA. CONCLUSION: The PS UKA provided mechanics closer to those of the normal knee joint. The decreased contact stress on the opposite compartment may reduce the overall risk of progressive osteoarthritis.Cite this article: K-T. Kang, J. Son, D-S. Suh, S. K. Kwon, O-R. Kwon, Y-G. Koh. Patient-specific medial unicompartmental knee arthroplasty has a greater protective effect on articular cartilage in the lateral compartment: A Finite Element Analysis. Bone Joint Res 2018;7:20-27. DOI: 10.1302/2046-3758.71.BJR-2017-0115.R2.

Revisits after adenotonsillectomy in children with sleep-disordered breathing: A retrospective single-institution study.

OBJECTIVE: To investigate emergency room (ER) revisits and hospital readmissions following adenotonsillectomy (T&A) in children with sleep-disordered breathing (SDB), and correlations between SDB severity and ER revisits. DESIGN: Retrospective chart review study. SETTING: Tertiary referral centre. PARTICIPANT: 610 consecutive children underwent T&A for treating SDB. MAIN OUTCOME MEASURES: Sleep-disordered breathing severity was defined according to the apnoea-hypopnoea index (AHI) (primary snoring = AHI < 1; mild = AHI 1-5; moderate = AHI 5-10; and severe = AHI > 10). Revisit and readmission patterns within 30 days of the surgery were extracted and analysed. RESULTS: Of these children (mean age = 7.2 years; males = 72%), 49 (8.0%) had first ER revisit, nine (1.5%) had second ER revisits, and one (0.2%) had third ER revisits. Reasons for ER revisits were bleeding related (46%) or non-bleeding related (54%). The timing for revisits was 6.9±1.9 postoperative days for bleeding-related revisits and 9.3±10.0 days for non-bleeding-related revisits. Treatment strategies during these revisits were treat and release in 44 children (74.6%), admission for observation in eight children (13.5%), and admission for surgery in seven children (11.9%). The incidence of ER revisit and hospital readmission was similar among children with all levels of SDB severity. Multivariable logistic regression analysis showed that young children (<3 years) experienced an increased risk of non-bleeding-related revisits (odds ratio [OR] = 4.1). CONCLUSIONS: Children with severe SDB do not experience increased risks of revisit or readmission; however, young children are at increased risk of non-bleeding-related revisits.

Computational study on the effect of malalignment of the tibial component on the biomechanics of total knee arthroplasty: A Finite Element Analysis.

OBJECTIVES: Malalignment of the tibial component could influence the long-term survival of a total knee arthroplasty (TKA). The object of this study was to investigate the biomechanical effect of varus and valgus malalignment on the tibial component under stance-phase gait cycle loading conditions. METHODS: Validated finite element models for varus and valgus malalignment by 3° and 5° were developed to evaluate the effect of malalignment on the tibial component in TKA. Maximum contact stress and contact area on a polyethylene insert, maximum contact stress on patellar button and the collateral ligament force were investigated. RESULTS: There was greater total contact stress in the varus alignment than in the valgus, with more marked difference on the medial side. An increase in ligament force was clearly demonstrated, especially in the valgus alignment and force exerted on the medial collateral ligament also increased. CONCLUSION: These results highlight the importance of accurate surgical reconstruction of the coronal tibial alignment of the knee joint. Varus and valgus alignments will influence wear and ligament stability, respectively in TKA.Cite this article: D-S. Suh, K-T. Kang, J. Son, O-R. Kwon, C. Baek, Y-G. Koh. Computational study on the effect of malalignment of the tibial component on the biomechanics of total knee arthroplasty: A Finite Element Analysis. Bone Joint Res 2017;6:623-630. DOI: 10.1302/2046-3758.611.BJR-2016-0088.R2.

Preservation of kinematics with posterior cruciate-, bicruciate- and patient-specific bicruciate-retaining prostheses in total knee arthroplasty by using computational simulation with normal knee model.

OBJECTIVES: Preservation of both anterior and posterior cruciate ligaments in total knee arthroplasty (TKA) can lead to near-normal post-operative joint mechanics and improved knee function. We hypothesised that a patient-specific bicruciate-retaining prosthesis preserves near-normal kinematics better than standard off-the-shelf posterior cruciate-retaining and bicruciate-retaining prostheses in TKA. METHODS: We developed the validated models to evaluate the post-operative kinematics in patient-specific bicruciate-retaining, standard off-the-shelf bicruciate-retaining and posterior cruciate-retaining TKA under gait and deep knee bend loading conditions using numerical simulation. RESULTS: Tibial posterior translation and internal rotation in patient-specific bicruciate-retaining prostheses preserved near-normal kinematics better than other standard off-the-shelf prostheses under gait loading conditions. Differences from normal kinematics were minimised for femoral rollback and internal-external rotation in patient-specific bicruciate-retaining, followed by standard off-the-shelf bicruciate-retaining and posterior cruciate-retaining TKA under deep knee bend loading conditions. Moreover, the standard off-the-shelf posterior cruciate-retaining TKA in this study showed the most abnormal performance in kinematics under gait and deep knee bend loading conditions, whereas patient-specific bicruciate-retaining TKA led to near-normal kinematics. CONCLUSION: This study showed that restoration of the normal geometry of the knee joint in patient-specific bicruciate-retaining TKA and preservation of the anterior cruciate ligament can lead to improvement in kinematics compared with the standard off-the-shelf posterior cruciate-retaining and bicruciate-retaining TKA.Cite this article: Y-G. Koh, J. Son, S-K. Kwon, H-J. Kim, O-R. Kwon, K-T. Kang. Preservation of kinematics with posterior cruciate-, bicruciate- and patient-specific bicruciate-retaining prostheses in total knee arthroplasty by using computational simulation with normal knee model. Bone Joint Res 2017;6:557-565. DOI: 10.1302/2046-3758.69.BJR-2016-0250.R1.

The effects of posterior cruciate ligament deficiency on posterolateral corner structures under gait- and squat-loading conditions: A computational knee model.

OBJECTIVES: The aim of the current study was to analyse the effects of posterior cruciate ligament (PCL) deficiency on forces of the posterolateral corner structure and on tibiofemoral (TF) and patellofemoral (PF) contact force under dynamic-loading conditions. METHODS: A subject-specific knee model was validated using a passive flexion experiment, electromyography data, muscle activation, and previous experimental studies. The simulation was performed on the musculoskeletal models with and without PCL deficiency using a novel force-dependent kinematics method under gait- and squat-loading conditions, followed by probabilistic analysis for material uncertain to be considered. RESULTS: Comparison of predicted passive flexion, posterior drawer kinematics and muscle activation with experimental measurements showed good agreement. Forces of the posterolateral corner structure, and TF and PF contact forces increased with PCL deficiency under gait- and squat-loading conditions. The rate of increase in PF contact force was the greatest during the squat-loading condition. The TF contact forces increased on both medial and lateral compartments during gait-loading conditions. However, during the squat-loading condition, the medial TF contact force tended to increase, while the lateral TF contact forces decreased. The posterolateral corner structure, which showed the greatest increase in force with deficiency of PCL under both gait- and squat-loading conditions, was the popliteus tendon (PT). CONCLUSION: PCL deficiency is a factor affecting the variability of force on the PT in dynamic-loading conditions, and it could lead to degeneration of the PF joint.Cite this article: K-T. Kang, Y-G. Koh, M. Jung, J-H. Nam, J. Son, Y.H. Lee, S-J. Kim, S-H. Kim. The effects of posterior cruciate ligament deficiency on posterolateral corner structures under gait- and squat-loading conditions: A computational knee model. Bone Joint Res 2017;6:31-42. DOI: 10.1302/2046-3758.61.BJR-2016-0184.R1.

Measuring the effect of femoral malrotation on knee joint biomechanics for total knee arthroplasty using computational simulation.

OBJECTIVES: Malrotation of the femoral component can result in post-operative complications in total knee arthroplasty (TKA), including patellar maltracking. Therefore, we used computational simulation to investigate the influence of femoral malrotation on contact stresses on the polyethylene (PE) insert and on the patellar button as well as on the forces on the collateral ligaments. MATERIALS AND METHODS: Validated finite element (FE) models, for internal and external malrotations from 0° to 10° with regard to the neutral position, were developed to evaluate the effect of malrotation on the femoral component in TKA. Femoral malrotation in TKA on the knee joint was simulated in walking stance-phase gait and squat loading conditions. RESULTS: Contact stress on the medial side of the PE insert increased with internal femoral malrotation and decreased with external femoral malrotation in both stance-phase gait and squat loading conditions. There was an opposite trend in the lateral side of the PE insert case. Contact stress on the patellar button increased with internal femoral malrotation and decreased with external femoral malrotation in both stance-phase gait and squat loading conditions. In particular, contact stress on the patellar button increased by 98% with internal malrotation of 10° in the squat loading condition. The force on the medial collateral ligament (MCL) and the lateral collateral ligament (LCL) increased with internal and external femoral malrotations, respectively. CONCLUSIONS: These findings provide support for orthopaedic surgeons to determine a more accurate femoral component alignment in order to reduce post-operative PE problems.Cite this article: K-T. Kang, Y-G. Koh, J. Son, O-R. Kwon, C. Baek, S. H. Jung, K. K. Park. Measuring the effect of femoral malrotation on knee joint biomechanics for total knee arthroplasty using computational simulation. Bone Joint Res 2016;5:552-559. DOI: 10.1302/2046-3758.511.BJR-2016-0107.R1.

Polysomnographic findings after adenotonsillectomy for obstructive sleep apnoea in obese and non-obese children: a systematic review and meta-analysis.

BACKGROUND: Use of polysomnography (PSG) is the gold standard of diagnosis and measurement of treatment effectiveness for paediatric obstructive sleep apnoea (OSA). Although adenotonsillectomy (T&A) is effective in diminishing the apnoea-hypopnoea index (AHI), a meta-analysis of postoperative changes for all other PSG parameters and outcome comparisons between obese and non-obese children following T&A have never been conducted. OBJECTIVE OF REVIEW: To comprehensively review polysomnographic findings after surgery for obese and non-obese children with OSA. SEARCH STRATEGY: Study protocol was registered on PROSPERO (CRD42013004737). Two authors independently searched databases including PubMed, MEDLINE, EMBASE and Cochrane Review from January 1997 to July 2014. The keywords used included the following: sleep apnea, OSA, sleep apnea syndromes, tonsillectomy, adenoidectomy, infant, child, adolescent, and Humans. EVALUATION METHOD: A comprehensive systematic review and meta-analysis for literature for OSA children treated by T&A with polysomnography data. Random-effects model was applied to determine postoperative sleep parameter changes and the surgical success rate between obese and non-obese groups. The quality of studies was assessed using the Newcastle-Ottawa Scale. RESULTS: In total, 51 studies with 3413 subjects were enrolled. After surgery, sleep architecture was altered by a significant decrease in sleep stage 1, and an increase in slow-wave sleep and the rapid eye movement stage, and enhanced sleep efficiency. The mean difference between pre- and postoperative was a significant reduction of 12.4 event/h in AHI, along with a reduction of obstructive index, hypopnoea index, central index and arousal index. Mean and minimum oxygen saturation increased significantly after surgery. The overall success rate was 51% for postoperative AHI <1 (obese versus non-obese versus combined, 34% versus 49% versus 56%), and 81% for AHI <5 (obese versus non-obese versus combined, 61% versus 87% versus 84%). Meta-regression analyses demonstrate that postoperative AHI was positively correlated with AHI and body mass index z score before surgery. CONCLUSIONS: Meta-analysis of current literature shows T&A offers prominent improvement in a variety of sleep parameters. Improvements in non-obese children exceeded those for obese children. Postoperative residual OSA remained in roughly half of the children, especially those with severe disease and obesity, making additional treatment strategies and/or long-term follow-up highly desirable.

Central sleep apnea in obese children with sleep-disordered breathing.

OBJECTIVES: In contrast to obstructive sleep apnea (OSA), central sleep apnea (CSA) in obese children has received lesser attention. As pediatric CSA is more prevalent than expected and adversely impacts health, this study aims to elucidate the major factors associated with central apnea index (CAI) and compare CSA between obese and non-obese children. METHODS: Retrospective analysis was performed in a tertiary referral medical center. Children with sleep-disordered breathing (SDB) ranging from 2-18 years old were enrolled. All participants completed history taking, otolaryngological examination and overnight polysomnography. CSA was defined as having CAI exceeding 1 h(-1). CAI and the prevalence of CSA were analyzed in children of different age groups, weight statuses and adenotonsillar sizes. RESULTS: A total of 487 cases were included. The prevalence of CSA was 13.3% (65/487). CAI was negatively correlated with age (r=-0.32, P<0.001). Obese children had a significantly lower CAI than that of non-obese ones (0.20 ± 0.36 vs 0.48 ± 0.82 h(-1), P<0.001). Multiple linear regression analysis demonstrated a relationship between CAI, age and obesity as 'CAI=0.883-0.055 × Age -0.22 × (Obesity)'. CONCLUSIONS: In children with SDB, younger ones have a significantly higher CAI than older ones. Additionally, obese children had a lower CAI than non-obese ones.

Systems for Paediatric Sepsis: A Global Survey.

OBJECTIVES: To evaluate the resources available for early diagnosis and treatment of paediatric sepsis at hospitals in developing and developed countries. METHODS: This was a voluntary online survey involving 101 hospitals from 41 countries solicited through the World Federation of Pediatric Intensive and Critical Care Societies contact list and website. The survey was designed to assess the spectrum of sepsis epidemiology, patterns of applied therapies, availability of resources and barriers to optimal sepsis treatment. RESULTS: Ninety per cent of respondents represented a tertiary or general hospital with paediatric intensive care facilities, including 63% from developed countries. Adequate triage services were absent in more than 20% of centres. Insufficiently trained personnel and lack of a sepsis protocol was reported in 40% of all sites. While there were specific guidelines for sepsis management in 78% of centres (n = 100), protocols for assessing sepsis patients were not applied in nearly 70% of centres. Lack of parental recognition of sepsis and failure of referring centres to diagnose sepsis were identified as major barriers by more than 50% of respondents. CONCLUSIONS: Even among centres with no significant resource constraints and advanced medical systems, significant deficits in sepsis care exist. Early recognition and management remain a key issue and may be addressed through improved triage, augmented support for referring centres and public awareness. Focussed research is necessary at the institutional level to identify and address specific barriers.

Short-term hypercaloric diet induces blunted aortic vasoconstriction and enhanced vasorelaxation via increased nitric oxide synthase 3 activity and expression in Dahl salt-sensitive rats.

AIM: To elucidate the role of the O(2)(-), H(2)O(2) or NO pathways in aortic angiotensin (Ang)II-induced vasoconstriction in Dahl salt-sensitive (SS) rats compared with control SS-13(BN) rats on a normal or hypercaloric diet. METHODS: Aortic function was assessed using wire myography in 16-week-old rats maintained on a normal diet or a 4-week hypercaloric diet. Nitric oxide synthase (NOS) activity and expression was determined by the conversion of radio-labelled arginine to citrulline and Western blot analysis respectively. RESULTS: On normal diet, AngII-induced vasoconstriction was greater in SS than SS-13(BN) rats. Polyethylene glycol superoxide dismutase (PEG-SOD) reduced the aortic AngII response similarly in both strains on normal diet. Catalase blunted, whereas N(ω)-Nitro-L-arginine methyl ester (L-NAME) did not affect the AngII response in SS rats. In SS-13(BN) rats, catalase had no effect and L-NAME enhanced AngII response. On hypercaloric diet, aortic AngII responsiveness was reduced in SS but unaltered in SS-13(BN) rats compared with their normal diet counterparts. PEG-SOD reduced the AngII response in both rats on hypercaloric diet. Catalase treatment did not alter aortic AngII response, while L-NAME increased the response in SS rats on hypercaloric diet. In SS-13(BN) rats on hypercaloric diet, catalase reduced and L-NAME did not alter the AngII response. Furthermore, aortic endothelial-dependent vasorelaxation was increased in SS rats on hypercaloric diet compared with normal diet and aortic NOS3 activity and expression was increased. CONCLUSION: A short-term hypercaloric diet induces a blunted vasoconstrictive and enhanced vasodilatory phenotype in SS rats, but not in SS-13(BN) rats, via reduced H(2)O(2) and increased NOS3 function.

Impacts of body weight after surgery for obstructive sleep apnea in children.

OBJECTIVE: To investigate the impacts of body weight status on surgical outcomes and shifts of body weight status after adenotonsillectomy(T&A) in children with obstructive sleep apnea (OSA). METHODS: From 2009 to 2011, 161 children (mean age, 7.0 ± 3.4 years; 78% boys) were included. All the children had clinical symptoms and preoperative polysomnographic evaluations diagnosis of OSA. Children were divided into four weight status groups (underweight, normal weight, overweight and obese), based on age and gender corrected body mass index (BMI). RESULTS: Following T&A, the four different weight status groups significantly improved in apnea/hypopnea index (AHI) and minimum oxygen saturation. However, 49.1% of the children (79/161) had residual OSA (AHI ≥ 1). The incidence of residual OSA (AHI ≥ 1) in the obese group was 75%, which was significantly higher than the other three groups (P<0.01). Weight status changes after T&A were documented, and 54% (13/24) of the underweight children shifted to normal weight status within 6 months after surgery. CONCLUSION: Although sleep parameters improved in all weight statuses, obese children had a higher incidence of residual OSA postoperatively. About half of the underweight children shifted to normal weight status after T&A.

Body weight status and obstructive sleep apnea in children.

OBJECTIVE: The relationship between weight status, adenotonsillar hypertrophy and obstructive sleep apnea (OSA) in children has not yet been well studied. As the sleep parameters may show a disparity in different weight statuses, this study examined the relationship between the data of over-night polysomnography and different weight statuses, as well as the impact of adenotonsillar hypertrophy on children with OSA. METHODS: Children with sleep disturbances were recruited from our clinics. Standard physical examinations, history taking, lateral neck roentgenography, and full-night polysomnography were obtained. Children were divided into four groups based on the age- and gender-corrected body mass index (BMI): underweight, normal weight, overweight and obese. An adenoidal/nasopharyngeal ratio of more than 0.67 was considered adenoidal hypertrophy. Tonsillar hypertrophy was defined as having Grade III tonsils or above. RESULTS: From July 2006 to January 2009, 197 children were included in this study. Obese children had a significantly higher apnea-hypopnea index (AHI), obstructive apnea index and lower minimum oxygen saturation (MinSaO(2)) than those of the other groups. Underweight children had the second highest AHI. A negative correlation was also found between BMI z scores and MinSaO(2) (r = -0.194; P = 0.007). Children with tonsillar hypertrophy (P = 0.001) were associated with a higher risk of having OSA. The risk of having OSA was significantly higher in obese children (P = 0.001) and underweight children (P = 0.043) than in those with a normal weight. CONCLUSION: Obesity, underweight status and tonsillar hypertrophy are associated with children having OSA, and obese children have a significantly higher risk than children with underweight status.

Sudden sensorineural hearing loss in a patient with primary antiphospholipid syndrome.

OBJECTIVE: Despite multiple systemic manifestations, sudden sensorineural hearing loss in a patient with antiphospholipid syndrome is rarely reported. PATIENT: A 46-year-old man with primary antiphospholipid syndrome had a sudden onset of hearing loss and tinnitus in the right ear in December 2005, because he discontinued use of warfarin and acetylsalicylic acid for a few days. RESULTS: Audiometry revealed saucer-type sensorineural hearing loss with a pure tone average of 73 dB in the right ear, and flat-type hearing loss with a pure tone average of 25 dB in the left ear. Electronystagmography displayed multiple central signs and bilateral canal paresis, while a vestibular evoked myogenic potential test revealed bilateral delayed responses. After admission, the patient was re-treated with warfarin and acetylsalicylic acid. Follow-up audiometry showed recovery of right-sided hearing, with a pure tone average of 12 dB, three days after presentation. CONCLUSION: Consensus exists on the effectiveness of anticoagulant agents in aiding a favourable outcome of sudden sensorineural hearing loss in patients with antiphospholipid syndrome.

Applications of phthalimide photochemistry to macrocyclic polyether, polythioether, and polyamide synthesis.

Irradiation of phthalimides which contain N-linked omega-trimethylsilylmethyl-substituted polyether, polythioether, and polysulfonamide chains results in efficient production of the corresponding macrocyclic polyether, polythioether, and polysulfonamide products. These photocyclization reactions follow sequential single electron transfer (SET)-desilylation pathways. Only in the cases of phthalimides, bearing mixed ether-thioether N-substituents, do these excited-state cyclization reactions proceed with lower degrees of regioselectivity. This is a result of competitive desilylation and alpha-to-sulfur deprotonation reactions of the zwitterionic diradical intermediates formed by initial SET.

Huge calcified aneurysm of the sinus of Valsalva.

Aneurysms of the sinus of Valsalva often remain undiagnosed until they rupture. A 61-year-old man had a huge, heavily calcified unruptured aneurysm, originating from the right sinus of Valsalva, detected incidentally on a chest radiograph taken for the diagnosis of cardiomegaly. Two-dimensional echocardiography revealed pericardial effusion with a huge calcified mass compressing the right ventricular outflow tract. The Doppler color-flow echocardiogram showed blood flow from the aortic root into the aneurysm. A chest computed tomographic scan revealed a large thrombosed aneurysm originating from the aortic root and measuring 10x10 cm. After pericardiocentesis, cardiac catheterization was performed, which showed that the right ventricular systolic pressure had elevated to 80 mmHg. Aortic root aortography demonstrated a huge unruptured calcified aneurysm in the sinus of Valsalva arising from the right coronary sinus. The patient underwent surgical correction to prevent aneurysmal rupture and to relieve the right ventricular outflow obstruction.

Clinical characteristics of unexplained sudden cardiac death in Korea.

In Western countries, sudden cardiac death (SCD) is closely related to coronary artery disease, but in Korea the clinical characteristics of SCD are not well determined. Over a 4-year period (June 1995 to May 1999), 186 cases of SCD, ranging in age from 16 to 75 years, were admitted to the Chonnam National University Hospital. In 82 (44.1%) of these, neither symptoms nor evidence of structural heart disease was found and so their clinical characteristics were investigated. There were 66 (80.5%) men and 16 (19.5%) women (male/female ratio = 4.1:1). The mean age was 50 +/- 14 years: 19 (23.2%) were in their 40s, 21 (25.6%) in their 50s, and 17 (20.7%) in their 60s. The time of circulatory collapse witnessed in 68 cases of SCD showed 2 peaks: between midnight and 03.00h (n=16, 23.5%) and between 09.00h and midday (n=15, 22.1%). Unexplained SCD occurred at home in 48 (64.9%) cases and on the street in 12 (16.2%); it occurred during normal daily routine activity in 23 (39.6%) and during sleep in 15 (25.9%). Thirty-three patients (40.2%) experienced various prodromal symptoms, including chest discomfort (n=13, 15.9%) and dyspnea (n=8, 9.8%). The electrocardiogram taken on arrival recorded asystole in 65 (79.3%) and ventricular fibrillation in 17 (20.7%). Idiopathic ventricular fibrillation was diagnosed in 14 (10 men, 4 women; 45 +/- 11 years) of 21 patients who recovered spontaneous circulation. Five (6.1%) patients were discharged alive, and an implantable cardioverter-defibrillator was implanted in 2. Unexplained SCD is common in Korea and develops predominantly in middle-aged males around midnight or in the late morning usually with no prodromal symptoms (59.8%). Idiopathic ventricular fibrillation is thought to be one of the important causes.