Endothelial dysfunction following coronary artery bypass grafting : Influence of patient and procedural factors.

BACKGROUND: Angiopoietin-2 (Angpt2) mediates endothelial dysfunction (ED) following coronary artery bypass grafting (CABG). Its triggers are, however, poorly understood. METHODS: We examined the time course of ED beyond the early phase of postoperative recovery in 75 patients following CABG with a special focus on different cardiopulmonary bypass (CPB) modes as potential triggers of Angpt2 release. RESULTS: Nine patients (12.0%) underwent off-pump coronary artery bypass (OPCAB), 31 patients (41.3%) received minimized extracorporeal circulation (MECC), and 35 patients (46.6%) were operated on with (conventional) CPB. Angpt2 levels steadily increased across the observation period (1.7 [1.4-2.1] to 3.4 [2.5-6.1] ng/ml, p < 0.001). Angpt2 levels did not differ between the MECC and CPB groups (p = 0.564). There was no difference between MECC and CPB patients regarding net fluid balance (p = 0.821) and other surrogate markers of postoperative ED. The magnitude of Angpt-2 increase correlated more strongly with baseline C­reactive protein (r = 0.459, p < 0.001) than with any other parameter. Hospital length of stay correlated more strongly with baseline Angpt2 levels (r = 0.512, p = 0.005) than with follow-up Angpt2 levels and appeared not to be influenced by CPB mode (p = 0.428). CONCLUSION: CABG is associated with prolonged ED, which is determined by the patient's preoperative inflammatory state rather than by CPB modifications.

Association between Hospitalization and Change of Frailty Status in the GAZEL Cohort.

OBJECTIVES: To assess the relationship between changes of frailty status and intervening hospitalizations, using information of the GAZEL cohort, matched with the data of the French National Health Data System. DESIGN: Observational cohort study. PARTICIPANTS: Community-dwelling adults of the GAZEL cohort (n = 12145; aged between 58 and 73 years in 2012). MEASUREMENTS: Frailty was determined with the Strawbridge questionnaire in 2012, 2013 and 2014. Data regarding hospitalizations (notably their number, length of stay, emergency department use, and main diagnosis) were collected from the French National Health Data System. The relationship between intervening hospitalizations and changes of frailty status over time was assessed with multivariate Markov models. RESULTS: The prevalence of frailty was 14% in 2012 and 2013 and 17% in 2014. A total of 2715 changes in frailty status were observed from 2012 to 2014. At least one hospitalization was recorded for 1453 people (12%) between the 2012 and 2013 questionnaires, and 1472 (13%) between the 2013 and 2014 questionnaires. No association was found between intervening hospitalizations and changes of frailty status (aHR 1.14 [0.97-1.35] for robust to frail transition and aHR 0.89 [0.73-1.08] for frail to robust transition). However, repeated hospitalizations, hospitalizations after emergency department use, surgery and several diagnosis groups were significantly associated with transitions towards frailty or its recovery. CONCLUSION: Hospitalizations encompass a wide range of clinical situations, some of them being associated with incident frailty. An early recognition of these situations could help to better prevent and manage frailty in the early old age.

Association Between Potentially Inappropriate Medications and Frailty in the Early Old Age: A Longitudinal Study in the GAZEL Cohort.

OBJECTIVES: High-risk prescribing can have deleterious effects on the health of older people. This study aimed to assess the role of inappropriate prescribing on changes in frailty status over 3 years of follow-up. DESIGN, SETTING: This is a prospective observational study nested in the GAZEL cohort. PARTICIPANTS: The study sample included 12,405 community-dwelling people aged 58 to 73 in 2012, and followed for 3 years. MEASUREMENT: Polypharmacy and potentially inappropriate medications (PIMs) were assessed from reimbursement data by the French National Health Insurance. Frailty was evaluated each year with the Strawbridge questionnaire. PIMs were defined according to the Laroche list plus additional criteria dealing with inappropriate prolonged use of medications. The relationship between PIMs and changes in frailty status (incident frailty and recovery) was analyzed with Markov multistate modeling. RESULTS: The prevalence of frailty increased from 14% in 2012 to 17% in 2014, whereas the frequency of PIMs was 29% in 2012 and 23% in 2014. Polypharmacy (5-9 drugs: aHR 1.31, 95% CI 1.14-1.50; and 10 drugs or more: aHR 1.57, 95% CI 1.28-1.92) and potentially inappropriate use of nonsteroidal anti-inflammatory drugs (aHR 1.33, 95% CI 1.04-1.71) were significantly associated with incident frailty, when the presence of at least 1 PIM presented a small association with the risk of becoming frail (aHR 1.15, 95% CI 1.01-1.32). CONCLUSIONS/IMPLICATIONS: This study brings new elements to our knowledge regarding the association between inappropriate prescribing and frailty in older adults, which support research development to alert on inappropriate prescribing and to improve drug prescribing among old people, especially with polypharmacy.

What are the preferences of patients attending a memory clinic for disclosure of Alzheimer's disease?

BACKGROUND/AIMS: This report shares and discusses the collected personal preferences of patients attending a memory clinic for disclosure of a potential Alzheimer's disease (AD) diagnosis. METHODS: In this prospective study of outpatients attending a single memory clinic over a 6-year period (March 2004-October 2010), doctors collected their patients' wishes (willingness to be informed, motivation, presence of the family) through a standardized procedure. RESULTS: Of the 1005 patients questioned throughout the study period-with a final diagnosis of dementia for 480 of them-858 (85.3%) wished to be informed of an AD diagnosis, whereas 72 (7.2%) did not and 75 (7.5%) were not sure. Older age and reduced cognitive functioning were independently associated with a preference to not be informed of a potential AD diagnosis. CONCLUSION: Our study provides evidence of the willingness of most patients to know the truth vis-à-vis AD and also offers some insight into their motivations.

[Non-inferiority and equivalence trials: Key methodological issues]. / Essais de non-infériorité et d'équivalence : les points clés de leur méthodologie.

Non-inferiority and equivalence trials aim to promote new treatments that are not expected to be superior to existing ones in a given indication. In order to compensate for a possible loss of efficacy, the new treatment should offer other advantages compared to the reference treatment, a better safety of use for example. Their methods somewhat differ from those of superiority trials, often better known to the medical community. This article presents the key points of the methodology of non-inferiority and equivalence trials in order to inform the readers of such trials about the issues and critical points. The general methodology (hypotheses, decision rules, number of subjects required, and strategy of analysis) is presented using examples and graphic illustrations. The issues and critical points are identified and discussed, in particular the choice of the comparator and of the margin of non-inferiority.

Small structural changes of the imidazopyridine diacylglycerol acyltransferase 2 (DGAT2) inhibitors produce an improved safety profile.

Small molecule DGAT2 inhibitors have shown promise for the treatment of metabolic diseases in preclinical models. Herein, we report the first toxicological evaluation of imidazopyridine-based DGAT2 inhibitors and show that the arteriopathy associated with imidazopyridine 1 can be mitigated with small structural modifications, and is thus not mechanism related.

Should Sensory Impairment Be Considered in Frailty Assessment? A Study in the GAZEL Cohort.

OBJECTIVES: The assessment of sensory difficulties is sometimes included in the screening of frailty in ageing population. This study aimed to compare the prevalence of frailty and associated risk of adverse outcomes depending on whether sensory difficulties participated in the definition of frailty. DESIGN: Prospective cohort study - GAZEL cohort. SETTING: France. PARTICIPANTS: The 13,128 subjects who completed a questionnaire in 2012. MEASUREMENTS: According to the Strawbridge questionnaire, subjects were considered frail if they reported difficulties in two domains or more among physical, nutritive, cognitive and sensory domains. The risk of adverse health outcomes was assessed by using logistic regression models (hospitalisations, onset of difficulty in performing movements of everyday life) and multivariate Cox proportional hazards models (mortality). RESULTS: Mean age was 66.8 +/- 3.4 years and 73.8% were males. The prevalence of frailty varied from 4.4 to 14.2% depending on whether the sensory domain was excluded or included. During follow-up, 182 deaths (1.4%), 479 hospitalisations (3.6%) and 703 cases of new disability (8.0%) were observed. Both definitions of frailty predicted the onset of difficulties to perform everyday movements, with 2 to 3-fold increase in the risk. The inclusion of the sensory domain in the definition made frailty predictive of hospitalisations (Odds Ratio 1.31 [1.01-1.70]) but the association with mortality was only observed when sensory difficulties were ignored (Hazard Ratio 2.28 [1.32-3.92]). CONCLUSION: The inclusion of a sensory domain into a frailty screening instrument has a major impact in terms of prevalence and modifies the risk profile associated with frailty. In order to develop the use of frailty screening instruments in clinical practice, further researches will need to carefully evaluate the impact on risk prediction of the different domains involved.

Health, frailty and disability after ninety: Results of an observational study in France.

BACKGROUND: In spite of their increasing demographic weight, health characteristics of the oldest old remain poorly described in epidemiological studies. OBJECTIVE: To describe the health of people aged 70 years and over included in the SIPAF study, and to compare the prevalence of health indicators including successful aging, frailty, and disability between three age groups including the oldest old. METHODS: The study population is composed of 2350 retired people recruited between 2008 and 2010, of whom 512 are aged 90 and over (21.8%). A comprehensive geriatric assessment was performed at home by trained nurses. The prevalence of health and functional indicators, as well as the distribution of people among successful ageing, frailty, and disability, were described by age group (70-79, 80-89, 90+) and sex. RESULTS: Compared to their younger counterparts, people aged 90 years and over were more likely to experience functional limitations, sensory impairment, cognitive impairment, poor mood, and frailty. One third of the nonagenarians needed help in at least one basic activity of daily living and 25% met the frailty criteria. In contrast, the prevalence of most chronic diseases did not increase after ninety. Successful ageing concerned 9% of the oldest old. Women were less likely to experience successful ageing and more likely to be frail or dependent. CONCLUSION: This study shows the diversity of health states in very old age and points out that one quarter of the people aged 90 and over said frail are likely to take advantage of preventive actions of disability.

[Use of social and health primary care services for older people with complex needs: Comparison of three types of gerontological coordination]. / Utilisation des services d'aide et de soins à domicile pour les personnes âgées en situations complexes : comparaison entre trois types de coordination gérontologique.

BACKGROUND: Older people with complex needs live mainly at home. Several types of gerontological coordinations have been established on the French territory to meet their needs and to implement social and primary health care services. But we do not have any information on the use of these services at home as a function of the coordination method used. METHODS: We compared the use of home care services for older people with complex needs in three types of coordination with 12 months' follow-up. The three coordinations regrouped a gerontological network with case management (n=105 persons), a nursing home service (SSIAD) with a nurse coordination (n=206 persons) and an informal coordination with a non-professional caregiver (n=117 persons). RESULTS: At t0, the older people addressed to the gerontological network had less access to the services offered at home; those followed by the SSIAD had the highest number of services and of weekly interventions. Hours of weekly services were two-fold higher in those with the informal coordination. At t12, there was an improvement in access to services for the network group with case management and an overall increase in the use of professional services at home with no significant difference between the three groups. CONCLUSION: The use of social and primary health care services showed differences between the three gerontological coordinations. The one-year evolution in the use of home services was comparable between the groups without an explosion in the number of services in the network group with case management.

Phase II study of gemcitabine, oxaliplatin in combination with panitumumab in KRAS wild-type unresectable or metastatic biliary tract and gallbladder cancer.

BACKGROUND: Current data suggest that platinum-based combination therapy is the standard first-line treatment for biliary tract cancer. EGFR inhibition has proven beneficial across a number of gastrointestinal malignancies; and has shown specific advantages among KRAS wild-type genetic subtypes of colon cancer. We report the combination of panitumumab with gemcitabine (GEM) and oxaliplatin (OX) as first-line therapy for KRAS wild-type biliary tract cancer. METHODS: Patients with histologically confirmed, previously untreated, unresectable or metastatic KRAS wild-type biliary tract or gallbladder adenocarcinoma with ECOG performance status 0-2 were treated with panitumumab 6 mg kg(-1), GEM 1000 mg m(-2) (10 mg m(-2) min(-1)) and OX 85 mg m(-2) on days 1 and 15 of each 28-day cycle. The primary objective was to determine the objective response rate by RECIST criteria v.1.1. Secondary objectives were to evaluate toxicity, progression-free survival (PFS), and overall survival. RESULTS: Thirty-one patients received at least one cycle of treatment across three institutions, 28 had measurable disease. Response rate was 45% and disease control rate was 90%. Median PFS was 10.6 months (95% CI 5-24 months) and median overall survival 20.3 months (95% CI 9-25 months). The most common grade 3/4 adverse events were anaemia 26%, leukopenia 23%, fatigue 23%, neuropathy 16% and rash 10%. CONCLUSIONS: The combination of gemcitabine, oxaliplatin and panitumumab in KRAS wild type metastatic biliary tract cancer showed encouraging efficacy, additional efforts of genetic stratification and targeted therapy is warranted in biliary tract cancer.

Influence of host and environmental factors on wheezing severity in infants: findings from the PARIS birth cohort.

BACKGROUND: Determinants of wheezing severity are poorly documented in infants. OBJECTIVES: To study the determinants of wheezing severity in infants aged 18 months followed-up in the PARIS (« Pollution and Asthma Risk : an Infant Study ¼) birth cohort. METHODS: Data on wheezing disorders, medical visits and medications, as well as biological markers of atopy, were collected during a medical examination at age 18 months. Severe wheeze was defined as wheeze that required inhaled corticosteroid and/or hospital-based care. Environmental exposures were assessed prospectively with regular questionnaires. Risk factors for wheeze in the first 18 months of life were assessed by multivariate regression models. RESULTS: Participation in the medical examination concerned 48.2% of the original cohort. Prevalence of wheeze was 560/1879 (35.7%) and was influenced by male gender, parental history of asthma, siblings, daycare attendance, heavy parental smoking at home, and carpet covered floor in the child's bedroom. Being overweight increased the risk of wheeze by 62% (OR = 1.62, 95%CI 1.13-2.32). In addition, trends towards an increased risk of wheeze were found in infants exposed to daily use of cleaning sprays and to renovation activities. Conversely, the presence of a cat reduced the risk of wheeze (OR = 0.65, 95%CI 0.47-0.89), without any evidence of healthy-pet keeping effect. Severe wheeze concerned 286 of the wheezers (42.7%). The prevalence of severe wheeze was related to atopy, and risk of severe wheeze was in particular increased in infants having eosinophilia (OR = 1.76, 95%CI 1.21-2.55) or being sensitized to ≥ 2 allergens (OR = 1.88, 95%CI 1.13-3.14). CONCLUSIONS AND CLINICAL RELEVANCE: Whilst risk factors for wheeze before 18 months of age are factors related to infections, indoor air pollution, and being overweight, the severity of wheeze is mainly due to the atopic status of the child. We suggest that atopy should be further considered in the assessment of wheezing severity in infants.

[Management of wheezing disorders in infants participating in the PARIS birth cohort]. / Prise en charge des sifflements chez le nourrisson dans la cohorte de nouveau-nés PARIS.

BACKGROUND: While wheezing disorders are common in preschool children, their management is not well defined. The aim of this study was to assess the use of medical health care resources due to wheezing disorders in infants aged 18 months followed up in the Pollution and Asthma Risk: an Infant Study (PARIS) birth cohort. METHODS: Data on wheezing disorders, medical visits and medication on account of respiratory disorders during the previous 12 months were collected with a standardized questionnaire, administered by a paediatrician, during the health check offered to every child aged 18 months included in the PARIS birth cohort. RESULTS: The prevalence of wheezing disorders during the past 12 months amounted to 560/1974 (28.4%). Among wheezers, 493 (89.3%) required a medical visit because of difficult breathing; 61 (11.0%) went to the emergency room, 35 (6.4%) were admitted to the hospital and 375 (67.2%) received an inhaled anti-asthmatic medication. Recourse to chest physiotherapy was reported in 472 of them (85.1%). CONCLUSION: This study confirms the high use of healthcare resources because of wheezing disorders in infants and suggests a higher use of anti-asthmatic medications in France compared to other European countries.

[Necrotizing fasciitis. 2011 update]. / Nekrotisierende Fasziitis. Update 2011.

Necrotizing fasciitis belongs to a group of complicated soft tissue infections that can be even life threatening. Despite growing knowledge about its etiology, predictors, and the clinical progression, the mortality remains at a high level with 20%. A relevant reduction can be achieved only by an early diagnosis followed by consistent therapy. The clinical findings in about 75% of the cases are pain out of proportion, edema and tenderness, blisters, and erythema. It is elementary to differentiate a necrotizing or a non-necrotizing soft tissue infection early. In uncertain cases it can be necessary to perform a surgical exploration to confirm the diagnosis. The histopathologic characteristics are the fascial necrosis, vasculitis, thrombosis of perforating veins, the presence of the disease-causing bacteria as well as inflammatory cells like macrophages and polymorphonuclear granulocytes. Secondly, both the cutis and the muscle can be affected. In many cases there is a disproportion of the degree of local and systemic symptoms. Depending on the infectious agents there are two main types: type I is a polymicrobial infection and type II is a more invasive, serious, and fulminant monomicrobial infection mostly caused by group A Streptococcus pyogenes.Invasive, severe forms of streptococcal infections seem to occur more often in recent years. Multimodal and interdisciplinary therapy should be based on radical surgical débridement, systemic antibiotic therapy as well as enhanced intensive care therapy, which is sometimes combined with immunoglobulins (in streptococcal or staphylococcal infections) or hyperbaric oxygen therapy (HBOT, in clostridial infections). For wound care of extensive soft tissue defects vacuum-assisted closure has shown its benefit.

Does allergic rhinitis exist in infancy? Findings from the PARIS birth cohort.

BACKGROUND: Early onset of allergic rhinitis (AR) is poorly described, and rhinitis symptoms are often attributed to infections. This study analyses the relations between AR-like symptoms and atopy in infancy in the PARIS (Pollution and Asthma Risk: an Infant Study) birth cohort. METHODS: Data on AR-like symptoms (runny nose, blocked nose, sneezing apart from a cold) were collected using a standardized questionnaire administered during the health examination at age 18 months included in the follow-up of the PARIS birth cohort. Parental history of allergy and children's atopy blood markers (blood eosinophilia ≥470 eosinophils/mm(3) , total immunoglobulin E ≥45 U/ml and presence of allergen-specific IgE) were assessed. Associations were studied using multivariate logistic regression models adjusted for potential confounders. RESULTS: Prevalence of AR-like symptoms in the past year was 9.1% of the 1850 toddlers of the study cohort. AR-like symptoms and dry cough apart from a cold were frequent comorbid conditions. Parental history of AR in both parents increased the risk of suffering from AR-like symptoms with an OR 2.09 (P=0.036). Significant associations were found with the presence of concurrent biological markers of atopy, especially blood eosinophilia and sensitization to house dust mite (OR 1.54, P=0.046 and OR 2.91, P=0.042) whereas there was no relation with sensitization to food. CONCLUSIONS: These results support the hypothesis that AR could begin as early as 18 months of life. Suspicion of AR should be reinforced in infants with parental history of AR or biological evidence of atopy, particularly blood eosinophilia and sensitization to inhalant allergens.

IgG and IgM levels in dairy cows during the periparturient period.

In dairy cows, the incidence of infectious diseases during the periparturient period is high. The most common diseases ante partum (a.p.) and post partum (p.p.) are mastitis and puerperal toxicaemia, puerperal septicaemia, and chronic endometritis, respectively. Studies suggest that this is related to an immunosuppressed status during this period. Therefore, the aim of this study was to determine the periparturient immune status characterized by concentrations of IgG and IgM in peripheral blood and colostrum samples of dairy cows and to assess in detail whether variations in immunoglobulin levels may be related to age and status of productivity. In addition, a possible correlation between the course of immunoglobulin levels and lymphocyte concentrations was assessed. Eighteen clinically healthy German Holstein and Red Holstein dams were selected for this study and sampled regularly between the 8(th) week a.p. and the 4(th) week p.p. IgG and IgM levels were determined using two novel competitive ELISAs. Results demonstrated a dramatic decrease of serum IgG and IgM levels beginning at the 8(th) week and 4(th) week a.p., respectively, both reaching trough at parturition. The IgG level recovered by the 4(th) week p.p., while IgM concentrations remained low. The extent of IgG reduction seemed to be dependent on the initial IgG concentration when the cow was dried-off (8(th) week a.p.). In contrast to IgM, the degree of IgG reduction correlated significantly with the IgG concentrations in the colostrum. Furthermore, a cross-correlation between the IgG levels and the lymphocyte counts was detectable (P < 0.01). In conclusion, the antepartal decline of blood IgG and IgM levels as well as the low periparturient IgG levels could reflect a "physiological phenomenon" of dairy cattle. If the phenomenon is associated with an unstable immune system, it must be assessed in future studies. Nonetheless, a sensitive immune system could explain the high incidence for infectious diseases during this period.

Changes of central haemodynamic parameters during mental stress and acute bouts of static and dynamic exercise.

Chronic dynamic (aerobic) exercise decreases central arterial stiffness, whereas chronic resistance exercise evokes the opposite effect. Nevertheless, there is little information available on the effects of acute bouts of exercise. Also, there is limited data showing an increase of central arterial stiffness during acute mental stress. This study aimed to determine the effect of acute mental and physical (static and dynamic exercise) stress on indices of central arterial stiffness. Fifteen young healthy volunteers were studied. The following paradigms were performed: (1) 2 min of mental arithmetic, (2) short bouts (20 s) of static handgrip at 20 and 70% of maximal voluntary contraction (MVC), (3) fatiguing handgrip at 40% MVC and (4) incremental dynamic knee extensor exercise. Central aortic waveforms were assessed using SphygmoCor software. As compared to baseline, pulse wave transit time decreased significantly for all four interventions indicating that central arterial stiffness increased. During fatiguing handgrip there was a fall in the ratio of peripheral to central pulse pressure from 1.69+/-0.02 at baseline to 1.56+/-0.05 (P<0.05). In the knee extensor protocol a non-significant trend for the opposite effect was noted. The augmentation index increased significantly during the arithmetic, short static and fatiguing handgrip protocols, whereas there was no change in the knee extensor protocol. We conclude that (1) during all types of acute stress tested in this study (including dynamic exercise) estimated central stiffness increased, (2) during static exercise the workload posed on the left ventricle (expressed as change in central pulse pressure) is relatively higher than that posed during dynamic exercise (given the same pulse pressure change in the periphery).

[Epidemiology of allergic respiratory disorders in infants]. / Epidémiologie des allergies respiratoires chez le nourrisson.

INTRODUCTION: Allergic disorders of the respiratory tract have been the subject of many epidemiological studies, especially during infancy which is known to be a critical period for development of the immune system. This paper aims to describe the prevalence of allergic respiratory disorders in children below three years of age in the general population, despite the lack of shared definition of asthma and allergic rhinitis among studies. STATE OF ART: Doctor-diagnosed asthma occurs in 5% of children below two years of age. One third of children below three years of age experience wheeze during a lower respiratory tract infection, but only 7% of children wheeze apart from a respiratory infection. Asthma-like cough and bronchial obstruction symptoms are reported in respectively 15% and 9% of children below two years of age. Depending on the definition of allergic rhinitis used, its prevalence varies from 1 to 30% among two years old children. PERSPECTIVES: Definitions of allergic respiratory tract disorders in infants become more elaborate involving parental and personal history of allergy and medication; epidemiological research now attempts to identify, using biological evidence of atopy, infants at risk of persistent allergic disorders. CONCLUSIONS: A better definition of allergic respiratory disorders in infants may help epidemiological research and early care management.

Multiaxial fatigue behavior of conventional and highly crosslinked UHMWPE during cyclic small punch testing.

Previous observations of reduced uniaxial elongation, fracture resistance, and crack propagation resistance of highly crosslinked ultrahigh molecular weight polyethylene (UHMWPE) have contributed to concern that the technology may not be appropriate for systems undergoing cyclic fatigue loading. Using a "total life" approach, we examined the influence of radiation crosslinking on the fatigue response of UHMWPE under cyclic loading via the small punch test. Our goal in this study was to evaluate the suitability of the small punch test for conducting miniature-specimen, cyclic loading, and fatigue experiments of conventional and highly crosslinked UHMWPE. We subjected four types of conventional and highly crosslinked UHMWPE to cyclic loading at 200 N/s and at body temperature in a small punch test apparatus. After failure, the fracture surfaces were characterized with the use of field emission scanning electron microscopy to evaluate the fatigue mechanisms. Cyclic small punch testing under load control was found to be an effective and repeatable method for relative assessment of the fatigue resistance of conventional and highly crosslinked UHMWPE specimens under multiaxial loading conditions. For each of the four conventional and highly crosslinked UHMWPE materials evaluated in this study, fatigue failures were consistently produced according to a power law relationship in the low cycle regimen, corresponding to failures below 10000 cycles. The fatigue failures were all found to be consistent with a single source of initiation and propagation to failure. Our long-term goal in this research is to develop miniature-specimen fatigue testing techniques for characterization of retrieved UHMWPE inserts.

Deconvolution of surface topology for quantification of initial wear in highly cross-linked acetabular components for THA.

Evaluation of the surface morphology of short-term retrieved cross-linked acetabular components requires differentiation between the features generated during machining and the smaller-scale morphologies generated during the in vivo wear process. Previously, the distinction between the waviness of machining and the roughness of wear has been related to the grain size of the UHMWPE. Here a low-frequency cutoff is proposed, based on the maximum spectral frequency of machining marks, rather than on the grain size of the bulk UHMWPE material, as a reliable method for deconvolving machining marks from in vivo wear following short-term implantation. To this end, as-machined articulating surfaces of conventional (GUR 1050) and two groups of highly cross-linked UHMWPE acetabular components were examined to determine whether they exhibited a periodic surface morphology with a well-defined spatial frequency. The surface frequency spectra revealed low-frequency peaks associated with the machining marks, which were unique to each type of implant. Furthermore, the surface frequency spectra appeared uniform within a single group of implants. Statistically significant differences in the surface roughness and waviness were observed between the three groups of new implants. Our research suggests that machining marks can be effectively deconvolved from the articulating surface with the use of a Fourier transform algorithm with a single cutoff frequency of 0.08 1/microm, corresponding to a wavelength of 12.5 microm. The results of this study provide a unified conceptual framework for discriminating between waviness and roughness of the articulating surface for machined orthopedic components. The distinction between waviness and roughness is expected to be crucial for the comprehensive evaluation of wear surfaces after short-term implantation, when machining marks may be partially worn away or plastically deformed in vivo.