Experimental characterisation for micromechanical modelling of CoCr stent fatigue

Fatigue of CoCr alloy stents has become a major concern in recent times, owing to cases of premature fracture, often driven by microstructural phenomena. This work presents the development of a micromechanical framework for fatigue design, based on experimental characterisation of a biomedical grade CoCr alloy, including both microscopy and mechanical testing. Fatigue indicator parameters (FIPs) within the micromechanical framework are calibrated for the prediction of microstructure-sensitive fatigue crack initiation (FCI). A multi-scale CoCr stent model is developed, including a 3D global J₂ continuum stent-artery model and a 2D micromechanical sub-model. Several microstructure realizations for the stent sub-model allow assessment of the effect of crystallographic orientations on stent fatigue crack initiation predictions. Predictions of FCI are compared with traditional Basquin-Goodman total life predictions, revealing more realistic scatter of data for the microstructure-based FIP approach. Comparison of stent predictions with performance of a 316L stent for the same generic design exposes the design as over-conservative for the CoCr alloy. In response, the micromechanical framework is used to modify the stent design for the CoCr alloy, improving design efficiency.     

Big Data and Total Hip Arthroplasty: How Do Large Databases Compare?

Background

Use of large databases for orthopedic research has become extremely popular in recent years. Each database varies in the methods used to capture data and the population it represents. The purpose of this study was to evaluate how these databases differed in reported demographics, comorbidities, and postoperative complications for primary total hip arthroplasty (THA) patients.

Comparison of three screening tools to detect psoriatic arthritis in patients with psoriasis (CONTEST study)

Background Multiple questionnaires to screen for psoriatic arthritis (PsA) have been developed but the optimal screening questionnaire is unknown. Objectives To compare three PsA screening questionnaires in a head‐to‐head study using CASPAR (the Classification Criteria for Psoriatic Arthritis) as the gold standard. Methods This study recruited from 10 U.K. secondary care dermatology clinics. Patients with a diagnosis of psoriasis, not previously diagnosed with PsA, were given all three questionnaires. All patients who were positive on any questionnaire were invited for a rheumatological assessment. Receiver operating characteristic (ROC) curves were used to compare the sensitivity, specificity and area under the curve of the three questionnaires according to CASPAR criteria. Results In total, 938 patients with psoriasis were invited to participate and 657 (70%) patients returned the questionnaires. One or more questionnaires were positive in 314 patients (48%) and 195 (62%) of these patients attended for assessment. Of these, 47 patients (24%) were diagnosed with PsA according to the CASPAR criteria. The proportion of patients with PsA increased with the number of positive questionnaires (one questionnaire, 19·1%; two, 34·0%; three, 46·8%). Sensitivities and specificities for the three questionnaires, and areas under the ROC curve were, respectively: Psoriatic Arthritis Screening Evaluation (PASE), 74·5%, 38·5%, 0·594; Psoriasis Epidemiology Screening Tool (PEST), 76·6%, 37·2%, 0·610; Toronto Psoriatic Arthritis Screen (ToPAS), 76·6%, 29·7%, 0·554. The majority of patients with a false positive response had degenerative or osteoarthritis. Conclusion Although the PEST and ToPAS questionnaires performed slightly better than the PASE questionnaire at identifying PsA, there is little difference between these instruments. These screening tools identify many cases of musculoskeletal disease other than PsA.     

Friendship at Any Cost: Parent Perspectives on Cyberbullying Children With Intellectual and Developmental Disabilities

Bullying affects approximately 40% of individuals with intellectual and developmental disabilities (IDD). Cyberbullying, a type of bullying facilitated by electronic devices, may be particularly worrisome for parents of children with IDD as constant monitoring is difficult. In this study, ten parents of Special Olympics Maryland athletes completed a survey and participated in in-depth, semi-structured interviews. Interview questions were based on the routine activities theory, whichposits that crime requires a vulnerable target, motivated offender, and lack of effective monitoring. Sixty percent of parents reported that their child with IDD had been bullied at school and, although quantitative analysis indicated no cyberbullying exposure, qualitative analysis implied two children had been cyberbullied. Results suggest parents perceive that individuals with IDD are vulnerable to cyberbullying, require constant monitoring, and have unique resource needs. Cyberbullying is an important health issue for those with IDD; additional research and targeted resources are needed.     

Adaptations in single-leg hop biomechanics following anterior cruciate ligament reconstruction

When a patient performs a clinically normal hop test based on distance, it cannot be assumed that the biomechanics are similar between limbs. The objective was to compare takeoff and landing biomechanics between legs in patients who have undergone anterior cruciate ligament reconstruction. Kinematics and ground reaction forces were recorded as 13 patients performed the single-leg hop on each leg. Distance hopped, joint range of motion, peak joint kinetics and the peak total extensor moment were compared between legs during both takeoff and landing. Average hop distance ratio (involved/noninvolved) was 93 ± 4%. Compared to the noninvolved side, knee motion during takeoff on the involved side was significantly reduced (P = 0.008). Peak moments and powers on the involved side were lower at the knee and higher at the ankle and hip compared with the noninvolved side (Side by Joint P = 0.011; P = 0.003, respectively). The peak total extensor moment was not different between legs (P = 0.305) despite a decrease in knee moment and increases in ankle and hip moments (Side by Joint P = 0.015). During landing, knee motion was reduced (P = 0.043), and peak power absorbed was decreased at the knee and hip and increased at the ankle on the involved side compared to the noninvolved side (P = 0.003). The compensations by other joints may indicate protective adaptations to avoid overloading the reconstructed knee.     

Orthostatic hypotension and subjective sleep quality in older people

Poor sleep quality and orthostatic hypotension are common complaints in an older population, and both are related to factors such as polypharmacy and depression. However, it is not known whether there is a direct association between the two. Our objective is to investigate a potential association between orthostatic blood pressure response and subjective sleep quality in older people. A within-subjects, cross-sectional design embedded in a larger longitudinal study design. Participants were recruited from the community to visit the TRIL clinic at St James's Hospital, where they underwent a structured medical and psychosocial assessment. A total of 505 community dwelling adults aged 60+ (321 females, mean age 72.44) were participated in this study. Orthostatic blood pressure responses were recorded during an active stand using Finometer equipment, and health-related factors such as pain ratings, co-morbidities, polypharmacy, timed up and go, Mini-Mental State Examination score, body mass index, as well as depression, anxiety, age and gender, were also recorded. Self-reported sleep quality was also assessed using the Pittsburgh Sleep Quality Index. The results showed that timed up and go, polypharmacy, depression, anxiety, gender and delayed recovery of blood pressure at orthostasis were associated with subjective poor sleep quality. There is an association between subjective sleep quality and delayed recovery of blood pressure at orthostasis, independent of mental health or polypharmacy effects, in older adults. This link may have implications for the management of sleep disorders in older people.     

A Transition Pilot Program for Adolescents With Sickle Cell Disease

IntroductionTransition from pediatric to adult care is challenging for adolescents with chronic illnesses, including those with sickle cell disease (SCD). We describe a pilot program created to facilitate transition from pediatric to adult care by helping adolescents with SCD identify an adult medical home.MethodsWe investigated the feasibility of this program by evaluation of overall participation, satisfaction, and acceptance. A secondary objective was to compare the proportion of adolescents who fulfilled a first appointment with an adult hematologist among participants and nonparticipants.ResultsDuring the first 18 months of the program, 83 adolescents were invited and 34 (41%) agreed to participate; 25 (74%) completed their first visit within 3 months after leaving the pediatric program, compared with 16 of 49 (33%) of nonparticipants (p = .0002). Overall, 41 of 83 adolescents (49%) completed an appointment with an adult SCD program, regardless of program participation, in contrast with 11 of 75 adolescents (15%) who did so during the 18 months before the program was created (p < .0001).DiscussionThis transition pilot program was feasible, and most adolescent participants with SCD established an adult medical home.