The difficult primary total knee arthroplasty: a review.

Primary total knee arthroplasty (TKA) is a reliable procedure with reproducible long-term results. Nevertheless, there are conditions related to the type of patient or local conditions of the knee that can make it a difficult procedure. The most common scenarios that make it difficult are discussed in this review. These include patients with many previous operations and incisions, and those with severe coronal deformities, genu recurvatum, a stiff knee, extra-articular deformities and those who have previously undergone osteotomy around the knee and those with chronic dislocation of the patella. Each condition is analysed according to the characteristics of the patient, the pre-operative planning and the reported outcomes. When approaching the difficult primary TKA surgeons should use a systematic approach, which begins with the review of the existing literature for each specific clinical situation.

Broadband performance of superdirective delay-and-sum beamformers steered to end-fire.

Linear arrays steered to end-fire provide superdirective robust performance if a constraint is imposed on the white-noise gain. Filter-and-sum beamformers achieve the maximum constrained directivity by tuning their complex weights over the frequency. Delay-and-sum beamformers have simpler structures, but their weights are fixed and optimized at a given frequency. This letter investigates the constrained directivity provided over a broad band by different delay-and-sum techniques. Complex weights and analytic signals attain near-optimal broadband performance over four octaves. Oversteered arrays using real weights and signals were found to attain superdirective performance over approximately two octaves. Hearing aids and directional hydrophones are potential applications for the considered arrays.

Infecciones invasivas por estreptococos de los grupos A, C y G en la Argentina / Invasive infectios due to group A, C and G streptococci in Argentina

Streptococcus pyogenes (estreptococo beta-hemolítico del grupo A) (SGA) y Streptococcus dysgalactiae subsp. equisimilis, (estreptococos beta-hemolíticos grupos C y G) (SDSE) son capaces de provocar enfermedades graves como la fascitis necrotizante y el síndrome de shock tóxico estreptocócico (SSTE) y de causar complicaciones posinfecciosas. El objetivo de este trabajo fue presentar resultados de un estudio multicéntrico y compararlo con diferentes estudios descriptivos previos sobre infecciones invasivas por estreptococos beta-hemolíticos de los grupos A, C y G, también realizados en la Argentina. Se incluyeron 54 pacientes de 0 a 15 años con infecciones invasivas por SGA (N=50) o SDSE (N=4) en forma prospectiva entre julio de 2011 y junio de 2012 en 28 centros de 17 ciudades argentinas. Se aisló S. pyogenes en 28 pacientes que presentaron bacteriemia, 6 de ellas sin foco. Cuatro pacientes (7,4%) presentaron SSTE, en todos los casos por S. pyogenes. La mortalidad fue del 2,0% para SGA. La evolución de los pacientes fue peor en los tres estudios anteriores respecto del actual: mayor porcentaje de casos de SSTE (diferencias no significativas) y mayor mortalidad (diferencia significativa respecto de dos estudios previos). Es probable que la morbimortalidad haya decrecido en esta última década en la Argentina posiblemente debido al uso temprano de clindamicina en las infecciones invasivas por S. pyogenes y SDSE, aunque no se puede descartar la diferente circulación de cepas virulentas. Esta apreciación además está sesgada por la inclusión de pacientes de distintos centros con diferentes formas de presentación inicial (AU)

Streptococcus pyogenes (group A ß-hemolytic streptococcus (GAS)) and Streptococcus dysgalactiae subsp. equisimilis (group C and G ß-hemolytic streptococcus (GCGS)) may cause severe diseases such as necrotizing fasciitis and streptococcal toxic shock syndrome (STSS) as well as postinfectious complications. The aim of this report was to present the results of a multicenter study and compare them with the results of different previous descriptive studies on invasive infections due to beta-hemolytic streptococcus groups A, C, and G that were also conducted in Argentina. Forty-five patients between 0 and 15 years of age with invasive infections due to GAS (N=50) or GCGS (N=4) were prospectively included in the study between July 2011 and June 2012 from 28 centers in 17 Argentine cities. S. pyogenes was isolated in 28 patients who presented with bacteremia, without a focus in six. Four patients (7.4%) had STSS, due to S. pyogenes in all of them. In patients with GAS, mortality rate was 2.0%. Outcome of the patients was worse in previous studies than in the present one: Percentages of cases with STSS (no significant difference) and mortality (significant difference) were higher. It is probable that over the last decade morbidity and mortality have decreased in Argentina, possibly due to the early use of clindamycin in invasive infections due to S. pyogenes and GCGS, although a different circulation of virulent strains cannot be ruled out. Additionally, this observation is biased by the inclusion of patients from different centers with different presentations at onset (AU)

Congenital fetal and neonatal visceral chylous effusions: neonatal chylothorax and chylous ascites revisited. A multicenter retrospective study.

This retrospective study was carried out at eight Neonatal Intensive Care Units (NICU) Centers worldwide on 33 newborns presenting at birth with pleural, pericardial, or abdominal chylous effusions. Diagnosis of chylous effusion is based on findings of fluid with a milk-like appearance, a concentration of triglycerides in pleural effusion >1.1 mmol/l, and a total cell count >1,000 cells/ml with a predominance of >80% lymphocytes. Thirty-three newborns met the inclusion criteria and were studied. Six subjects who presented at birth with fetal effusion were treated by in-utero pleuro-amniotic shunt. Five of these patients are alive at follow-up. At birth, pleural drainage was performed in 29/33 patients and abdominal drainage was carried out in 3/33. Total parenteral nutrition (TPN) was given to 32/33 patients; 19/23 patients were fed a medium-chain triglycerides (MCT). No adverse effects were observed. Eight patients were treated with Octreotide at dosages ranging from 1 to 7 mcg/kg/hour for 8 to 35 days. All patients showed decreased chylous production. Two patients were treated by pleurodesis. Twenty-two babies are alive after at least 6 months follow-up, 9/33 are deceased, and 2 were lost to follow-up. Clinical conditions of survivors are basically good except for lung involvement [chronic lung disease (CLD) or lung lymphangiectasia] and lymphedema. All patients were using a MCT diet at follow-up with good control of chylous effusion. Visceral chylous effusions of the fetus and neonate are rare disorders, and there currently is only partial agreement on decision-making strategies. We suggest the need for an international prospective trial in an effort to establish the efficacy and effectiveness of diagnostic and therapeutic options described in this article.

Impacto de la resistencia a la meticilina sobre la mortalidad y vigilancia de la sensibilidad a la vancomicina en bacteriemias causadas por Staphylococcus aureus / Impact of methicillin resistance on mortality and surveillance of vancomycin susceptibility in bacteremias caused by Staphylococcus aureus

Staphylococcus aureus es uno de los principales patógenos nosocomiales y produce una alta morbimortalidad en numerosos hospitales del mundo. Además, la incidencia de bacteriemias por este microorganismo ha aumentado significativamente en las últimas décadas. Los objetivos del presente trabajo fueron identificar los factores de riesgo que favorecen la aparición de resistencia a la meticilina en aislamientos de S. aureus y los factores que afectan la mortalidad por bacteriemias asociadas a este patógeno, así como evaluar la sensibilidad a la vancomicina de las cepas resistentes a la meticilina. Se estudiaron 39 aislamientos de S. aureus provenientes de hemocultivos de pacientes internados con bacteriemia en la Nueva Clínica Chacabuco de Tandil (Pcia. de Buenos Aires, Argentina) en el período 01/2006-12/2008. La mortalidad global fue del 51,3% y estuvo significativamente asociada con la resistencia a la meticilina (OR: 4,20; IC95%: 1,08-16,32; p: 0,05); aunque dicho factor no fue un predictor independiente de mortalidad. La cirugía previa (OR: 17,23; IC95%: 1,80-164,60) y la estancia previa en la unidad de cuidados intensivos (OR: 21,12; IC95%: 2,33-191,30) fueron predictores independientes de la resistencia a la meticilina y la asistencia respiratoria mecánica (OR: 15,99; IC: 3,24-78,86) fue un predictor independiente de la mortalidad. No se detectaron cepas con sensibilidad disminuida a la vancomicina. Todos los aislamientos estudiados fueron sensibles in vitro a la vancomicina, con una CIM50 y una CIM90 de 0,5 μg/ml.

Staphylococcus aureus is a major nosocomial pathogen that causes severe morbidity and mortality in many hospitals worldwide. Besides, the incidence of S. aureus bacteremia has significantly increased over the past decades. The aims of this study were to detect the risk factors for methicillin resistance and mortality and to evaluate vancomycin susceptibility in methicillin-resistant isolates. Thus, 39 S. aureus isolates from blood cultures of hospitalized patients with bacteremia were studied in Nueva Clínica Chacabuco Tandil, Buenos Aires, Argentina during 01/2006-12/2008. The overall mortality was 51.3%, which was significantly associated with methicillin resistance (OR: 4.20, IC95%: 1.08-16.32, p: 0.05), even though it was not an independent mortality predictor as it was the mechanical ventilation (OR: 15.99, IC95%: 3.24 - 78.86). Previous surgery (OR: 17.23, IC95%: 1.80-164.60) and hospitalization in intensive care units (OR: 21.12, IC95%: 2.33-191.30) were independent predictors of meticillin-resistance. No isolates were found with reduced vancomycin susceptibility. All the studied isolates were in vitro susceptible to vancomycin with a MIC50 and MIC90 of 0.5 μg/ml.

[Molecular characterization of Streptococcus pyogenes from invasive disease and streptococcal toxic shock syndrome episodes]. / Caracterización molecular de Streptococcus pyogenes causantes de enfermedad invasora y síndrome de shock tóxico estreptocócico.

Streptococcus pyogenes causes a variety of common human diseases, including pharyngitis, scarlet fever and impetigo. Nevertheless, the past decades have witnessed a worldwide resurgence in invasive disease and streptococcal toxic shock syndrome (STSS). The objective of the present study is to evaluate the genetic diversity, virulence gene distribution (spe, sme and ssa genes) and susceptibility pattern of 10 S. pyogenes isolates causing invasive disease and STSS. The isolates were recovered from blood cultures of hospitalized patients at Hospital Santamarina and Nueva Clínica Chacabuco, Tandil, Buenos Aires, Argentina between 12/2000-04/2005. Two pulse field gel electrophoretic patterns predominated. The most frequent one included 5 characteristic isolates of emm1-T1 type, toxin gene profile speA, speB, speF, speG and smeZ. The second pattern included 2 characteristic isolates of emm3-TNT type (speB, speF, speG). The other 3 isolates corresponded to types emm49-TNT (speB, speC, speF, speG), emm75-T25 (speB, speF, speG) and emm83-TNT (speB, speF, speG, ssa, smeZ). All isolates were susceptible to penicillin, cefotaxime, erythromycin, clindamycin, chloramphenicol, tetracycline and rifampicin. The data from the present study demonstrated genetic diversity among the strains. Types emm1 and emm3 were prevalent in invasive disease. The empirical treatment with the combination of penicillin and clindamicin is still valid.

[Impact of methicillin resistance on mortality and surveillance of vancomycin susceptibility in bacteremias caused by Staphylococcus aureus]. / Impacto de la resistencia a la meticilina sobre la mortalidad y vigilancia de la sensibilidad a la vancomicina en bacteriemias causadas por Staphylococcus aureus.

Staphylococcus aureus is a major nosocomial pathogen that causes severe morbidity and mortality in many hospitals worldwide. Besides, the incidence of S. aureus bacteremia has significantly increased over the past decades. The aims of this study were to detect the risk factors for methicillin resistance and mortality and to evaluate vancomycin susceptibility in methicillin-resistant isolates. Thus, 39 S. aureus isolates from blood cultures of hospitalized patients with bacteremia were studied in Nueva Clínica Chacabuco Tandil, Buenos Aires, Argentina during 01/2006-12/2008. The overall mortality was 51.3%, which was significantly associated with methicillin resistance (OR: 4.20, IC95%: 1.08-16.32, p: 0.05), even though it was not an independent mortality predictor as it was the mechanical ventilation (OR: 15.99, IC95%: 3.24 - 78.86). Previous surgery (OR: 17.23, IC95%: 1.80-164.60) and hospitalization in intensive care units (OR: 21.12, IC95%: 2.33-191.30) were independent predictors of meticillin-resistance. No isolates were found with reduced vancomycin susceptibility. All the studied isolates were in vitro susceptible to vancomycin with a MIC50 and MIC90 of 0.5 µg/ml.

Type II sialidosis: review of the clinical spectrum and identification of a new splicing defect with chitotriosidase assessment in two patients.

Sialidosis is a lysosomal storage disease caused by the deficiency of alpha-N-acetyl neuraminidase-1 (NEU1). Sialidosis is classified into two main clinical variants: Type I, the milder form of the disease, and Type II, which can in turn be subdivided into three forms: congenital, infantile and juvenile. We report herein the clinical, biochemical and molecular characterisation of two patients with Type II sialidosis exhibiting the congenital (P1) and infantile forms (P2). We also review clinical data on the rare Type II forms of sialidosis in the hope of improving understanding of the disorder and facilitating its diagnosis. The genetic characterization of the two patients showed one known [c. 679G > A (p.G227R)] NEU1 missense mutation (detected in P2), and the new c.807 + 1G > A splicing defect (detected in P1), a genetic lesion that is extremely rare in this disease. Interestingly, P2 presented an extremely elevated level of chitotriosidase in plasma. This is the first pathological detection of chitotriosidase in sialidosis patients.

The magnitude of early response to methotrexate therapy predicts long-term outcome of patients with juvenile idiopathic arthritis.

OBJECTIVE: To investigate the relationship between the magnitude of clinical response in the first 6 months of methotrexate (MTX) therapy and long-term outcome in children with juvenile idiopathic arthritis (JIA). METHODS: The clinical charts of 125 JIA patients who were started with MTX and then followed for at least 5 years were reviewed. Based on the level of American College of Rheumatology (ACR) Pediatric response at 6 months, patients were divided in four mutually exclusive groups: (1) non-responders, (2) responders at 30%, (3) responders at 50%, and (4) responders at 70%. The long-term outcome in each response group was evaluated by calculating the percentage change in active and restricted joint counts from baseline to 1, 2 and 5 years and the frequency of inactive disease at 5 years. RESULTS: At 6 months, 42 patients were classified as non-responders, 24 as 30% responders, 26 as 50% responders, and 33 as 70% responders. Patients who had achieved a 70% response showed a significantly greater percentage improvement in active joint count between baseline to 5 years compared with non-responders and 30% responders, and a significantly greater percentage improvement in restricted joint count between baseline to 5 years compared with 30% responders. The 70% responders also had a greater frequency of inactive disease at 5 years compared with 30% responders, CONCLUSIONS: Our results show that the achievement of an ACR Pediatric 70 response at 6 months after start of MTX therapy predicts a more favorable long-term outcome of patients with JIA.

[Targets and prevention of complications in nursing of subarachnoid hemorrhage]. / Compiti assistenziali e preventivi del nursing nell'ESA.

A qualified nursing care is mandatory in patients after SAH. Clinical and instrumental monitoring are basilar to assure the rapid control of dangerous ICP or CPP changes and of epileptic crisis. Prophylaxis of infections is greatly minimized when coherent treatments are applied to any invasive devices, patient body, patient bed and UTI area. Many drugs can be useful to avoid ICP increases by tracheal suctioning and other sensorial stimulations. Having a trained staff, patient outcome can be improved.

Vasculitic neuropathy associated with beta-haemolytic streptococcal infection: a case report.

Vasculitic neuropathy is rarely associated with a definable collagen vascular disease. Peripheral neuropathy may be the sole manifestation of vasculitis, and the aetiology is frequently unknown. We here report the case of a woman presenting mononeuritis multiplex, whose sural nerve biopsy was diagnostic of necrotizing vasculitis. There was serological evidence of preceding beta-haemolytic streptococcal infection. We assume that vasculitic neuropathy can be included among the possible sequelae of streptococcal infections.

Benign intracranial hypertension associated with HIV infection.

We report the case of a 24-year-old woman with HIV-seropositivity, who developed a clinical picture of pseudotumor cerebri, an association not previously described. The patient improved with the use of acetazolamide. We suggest the possible existence of this disorder in HIV-infected patients with persistent headaches, visual deficits and/or extraocular muscle palsies.

A family with hereditary intracerebral cavernous angiomas.

There are a very few reports in literature of inherited intracerebral cavernous angiomas. The majority of them are Mexican-American families. In some of the reported families autosomal dominant transmission is suggested. We report a family in which three members of three consecutive generations were proven to have multiple intracerebral cavernous malformations, without involvement of skin, eyes, or other viscera. An autosomal dominant mode of inheritance is clearly suggested.

Triphasic waves in Alzheimer's disease.

Clinical records and EEGs of 114 consecutive patients with clinical diagnosis of Alzheimer's disease have been reviewed. The EEGs of 15 patients (13%) contained triphasic waves. Triphasic waves were always atypical as they occurred singularly or in short bursts, and/or they had occipital predominance, and/or they were bilateral but asymmetrical. Triphasic waves, in all but one patient were recorded in a state of complete alertness. No statistically significant differences were found between the triphasic waves group and the other one, with respect to age, age at onset, illness duration, presence of seizures. Myoclonus was more frequent in patients with triphasic waves (p less than 0.01). Triphasic waves patients had a higher degree of dementia (p less than 0.01), both in cases with rapidly evolving disease and in subjects with relatively slow clinical course.

[Triphasic waves in dementia syndromes]. / Le onde trifasiche nelle sindromi demenziali.

Seventy-one EEGs (0.49%) of 53 patients, out of 14,458 recordings, contained triphasic waves: twenty-nine were patients with metabolic encephalopathies and 24 were demented patients (16 of these had a presumptive diagnosis of Alzheimer's disease and the other eight of mult-infarct dementia). Demented subjects with metabolic disorders are included in the metabolic encephalopathies group. In all of the cases of Alzheimer's disease, triphasic waves were atypical: in 14 they occurred singly or in short bursts, in 10 they had occipital predominance and in 2 they were bilateral but asymmetrical. In 5 cases, triphasic waves were associated with myoclonus and in 2 of them they occurred in long runs with a pseudo-periodic pattern. In these cases the distinction from Creutzfeldt-Jakob disease was based on neuropathologic findings.

Zoster sine herpete causing encephalomyelitis.

The case of a patient with encephalomyelitis and laboratory signs of a central nervous system herpes zoster infection without cutaneous lesions is reported. The diagnosis was supported by the serological evidence of intrathecal synthesis of specific antibodies against Varicella-zoster virus (VZV).