Aseptic loosening of the option stemmed tibial tray in the Zimmer NexGen LPS total knee arthroplasty system.

BACKGROUND: We investigated the relationship between the backside deformation of polyethylene (PE) tibial inserts and aseptic loosening of the Option stemmed tibial tray used with Zimmer NexGen posterior-stabilised (PS) devices. We hypothesized that explanted inserts used in PS designs would exhibit greater extents of PE backside deformation than those used in equivalent cruciate retaining (CR) designs and that PE inserts retrieved from total knee arthroplasties (TKAs) revised for aseptic tibial tray loosening would exhibit greater extents of backside deformation than TKAs revised for other reasons. METHODS: A total of 73 explanted fixed-bearing TKAs (42 CR and 31 PS) were examined. PE components underwent geometric examination with a coordinate measuring machine using validated techniques. Multiple regression modelling was used to identify variables associated with revision secondary to aseptic loosing and to determine factors associated with increased PE backside deformation. RESULTS: PE inserts retrieved from TKAs with aseptic loosening had significantly greater backside deformation than those retrieved from TKAs revised for other reasons (p < 0.001). Greater PE backside deformation was significantly associated with larger tray/insert clearance heights (p < 0.001), thinner inserts (p < 0.001) and PS TKAs (p = 0.001). CONCLUSION: PE backside deformation was significantly greater in the PS TKAs. This may provide one explanation for the increased rate of aseptic loosening reported with the Option tibial tray used with the Legacy Posterior Stabilised (LPS) system.

The influence of HLA genotype on the development of metal hypersensitivity following joint replacement.

Background: Over five million joint replacements are performed across the world each year. Cobalt chrome (CoCr) components are used in most of these procedures. Some patients develop delayed-type hypersensitivity (DTH) responses to CoCr implants, resulting in tissue damage and revision surgery. DTH is unpredictable and genetic links have yet to be definitively established. Methods: At a single site, we carried out an initial investigation to identify HLA alleles associated with development of DTH following metal-on-metal hip arthroplasty. We then recruited patients from other centres to train and validate an algorithm incorporating patient age, gender, HLA genotype, and blood metal concentrations to predict the development of DTH. Accuracy of the modelling was assessed using performance metrics including time-dependent receiver operator curves. Results: Using next-generation sequencing, here we determine the HLA genotypes of 606 patients. 176 of these patients had experienced failure of their prostheses; the remaining 430 remain asymptomatic at a mean follow up of twelve years. We demonstrate that the development of DTH is associated with patient age, gender, the magnitude of metal exposure, and the presence of certain HLA class II alleles. We show that the predictive algorithm developed from this investigation performs to an accuracy suitable for clinical use, with weighted mean survival probability errors of 1.8% and 3.1% for pre-operative and post-operative models respectively. Conclusions: The development of DTH following joint replacement appears to be determined by the interaction between implant wear and a patient's genotype. The algorithm described in this paper may improve implant selection and help direct patient surveillance following surgery. Further consideration should be given towards understanding patient-specific responses to different biomaterials.

Rationale and protocol for the Nursing and Allied Health Graduate Outcomes Tracking (NAHGOT) study: a large-scale longitudinal investigation of graduate practice destinations.

INTRODUCTION: Inequitable distribution of health workforce limits access to healthcare services and contributes to adverse health outcomes. WHO recommends tracking health professionals from their points of entry into university and over their careers for the purpose of workforce development and planning. Previous research has focused on medical students and graduates' choice of practice location. Few studies have targeted nursing and allied health graduates' practice intentions and destinations. The Nursing and Allied Health Graduate Outcomes Tracking (NAHGOT) study is investigating factors affecting Australian nursing and allied health students and graduates' choice of graduate practice location over the course of their studies and up to 10 years after graduation by linking multiple data sources, including routinely collected university administrative and professional placement data, surveys of students and graduates, and professional registration data. METHODS: By using a prospective cohort study design, each year a new cohort of about 2000 students at each participating university (Deakin University, Monash University and the University of Newcastle) is tracked throughout their courses and for 10 years after graduation. Disciplines include medical radiation practice, nursing and midwifery, occupational therapy, optometry, paramedicine, pharmacy, physiotherapy, podiatry and psychology. University enrolment data are collected at admission and professional placement data are collected annually. Students' practice destination intentions are collected via questions added into the national Student Experience Survey (SES). Data pertaining to graduates' practice destination, intentions and factors influencing choice of practice location are collected in the first and third years after graduation via questions added to the Australian Graduate Outcomes Survey (GOS). Additionally, participants may volunteer to receive a NAHGOT survey in the second and fourth-to-tenth years after graduation. Principal place of practice data are accessed via the Australian Health Practitioner Regulation Agency (Ahpra) annually. Linked data are aggregated and analysed to test hypotheses comparing associations between multiple variables and graduate practice location. RESULTS: This study seeks to add to the limited empirical evidence about factors that lead to rural practice in the nursing and allied health professions. This prospective large-scale, comprehensive study tracks participants from eight different health professions across three universities through their pre-registration education and into their postgraduate careers, an approach not previously reported in Australia. To achieve this, the NAHGOT study links data drawn from university enrolment and professional placement data, the SES, the GOS, online NAHGOT graduate surveys, and Ahpra data. The prospective cohort study design enables the use of both comparative analysis and hypothesis testing. The flexible and inclusive study design is intended to enable other universities, as well as those allied health professions not regulated by Ahpra, to join the study over time. CONCLUSION: The study demonstrates how the systematic, institutional tracking and research approach advocated by the WHO can be applied to the nursing and allied health workforce in Australia. It is expected that this large-scale, longitudinal, multifactorial, multicentre study will help inform future nursing and allied health university admission, graduate pathways and health workforce planning. Furthermore, the project could be expanded to explore health workforce attrition and thereby influence health workforce planning overall.

Profile and rural exposure for nursing and allied health students at two Australian Universities: A retrospective cohort study.

OBJECTIVE: Linking enrolment and professional placement data for students' from 2 universities, this study compares characteristics across universities and health disciplines. The study explores associations between students' location of origin and frequency, duration and type of placements. DESIGN: Retrospective cohort data linkage. SETTING: Two Australian universities, Monash University and the University of Newcastle. PARTICIPANTS: Students who completed medical radiation science, nursing, occupational therapy, pharmacy or physiotherapy at either university between 2 February 2017 and 28 February 2018. INTERVENTIONS: Location of origin, university and discipline of enrolment. MAIN OUTCOME MEASURE(S): Main measures were whether graduates had multiple rural placements, number of rural placements and cumulative rural placement days. Location of origin, discipline and university of enrolment were the main explanatory variables. Secondary dependent variables were age, sex, socio-economic indices for location of origin, and available placements. RESULTS: A total of 1,315 students were included, of which 22.1% were of rural origin. The odds of rural origin students undertaking a rural placement was more than 4.5 times greater than for urban origin students. A higher proportion of rural origin students had multiple rural placement (56.0% vs 14.9%), with a higher mean number of rural placement days. Public hospitals were the most common placement type, with fewer in primary care, mental health or aged care. CONCLUSIONS: There is a positive association between rural origin and rural placements in nursing and allied health. To help strengthen recruitment and retention of graduates this association could be further exploited, while being inclusive of non-rural students.

Struggling urology trainee: a qualitative study into causes of underperformance.

BACKGROUND: Urological surgical trainees who underperform are difficult to identify, manage and require significant resources in an already stretched system relying on pro bono supervisors that often have no formal training. While there are commentaries on how to manage underperforming surgical trainees, there is a lack of data detailing the complex reasons for underperformance. It is important to understand the complexities contributing to underperformance so that improved remediation plans can be developed which can better help trainees meet expectations and succeed. METHODS: In this qualitative study, individual semi-structured interviews were conducted with key persons identified as having very high levels of background knowledge and involvement with current underperforming urological surgery trainees. Transcribed interviews were thematically analysed. RESULTS: Ten interviews were conducted, including nine urology consultants and one educational manager. Five themes were identified: underperformance is a small but profound issue; spiral of failure; the changing trainee; lack of insight and under supported supervisors and posts. CONCLUSION: Causes of underperformance in urology trainees are complex and multifactorial. Behavioural issues were considered the most likely cause, which are also the most challenging to remedy. However, in addition to trainee factors, causative factors related to supervision and training were identified. Addressing all of these issues is paramount if effective remediation of these trainees is to occur.

Investigation of Taper Failure in a Contemporary Metal-on-Metal Hip Arthroplasty System Through Examination of Unused and Explanted Prostheses.

BACKGROUND: Large-diameter (≥36-mm) metal-on-metal (MoM) total hip replacements have been shown to fail at an unacceptably high rate. Globally, the DePuy Pinnacle prosthesis was the most widely used device of this type. There is evidence to suggest that one of the main reasons for the poor clinical performance of large-diameter MoM prostheses is the metal debris released from the head-stem taper junction-i.e., taper junction failure. The aim of this study was to investigate variation in the as-manufactured finish of the female taper surface and to determine its influence on material loss. We hypothesized that rougher surfaces with higher relative material peaks would be significantly associated with greater taper wear rates. METHODS: We analyzed 93 Articul/eze femoral head tapers with a 36-mm bearing diameter that had been used in combination with a Corail titanium uncemented stem. The influence of the surface topography of the as-manufactured female taper surface on taper wear was examined by means of a multiple regression model, taking into account other known variables. RESULTS: We identified great variation in the as-manufactured surface finish of the female taper surface, with a range of measured Ra values from 0.14 to 4.20 µm. The roughness of the female taper surface appeared to be the most important variable associated with taper wear (p < 0.001). The best-fitting regression model, including duration in vivo, head offset, reduced peak height (Rpk) value, stem shaft angle, and bearing surface wear rate, explained approximately 44% of the variation in taper wear rates. CONCLUSIONS: We concluded that the roughness of the female taper surface appears to be a significant factor in metal debris release from head-stem taper junctions. CLINICAL RELEVANCE: This study shows evidence that previously unappreciated variations in manufacturing processes may have a major impact on the clinical outcomes of patients.

Transient retinal effects of 5,6-dimethylxanthenone-4-acetic acid (DMXAA, ASA404), an antitumor vascular-disrupting agent in phase I clinical trials.

PURPOSE: 5,6-Dimethylxanthenone-4-acetic acid (DMXAA), an anticancer vascular-disrupting agent, has induced transient visual symptoms in some patients. Exploratory investigations were undertaken to characterize the visual disturbances in two consecutive phase I trials. METHODS: Assessments were made in 21 patients before and immediately after a 20-minute IV infusion of DMXAA, including visual acuity, funduscopy, color discrimination, pattern electroretinography (PERG), pattern visual-evoked potentials (VEP), and full-field electroretinography (ERG). Evaluation of late effects was undertaken subsequently in 12 patients before and after 6 weeks of IV DMXAA at one dose per week. RESULTS: Frequency and intensity of transient visual disturbance increased with DMXAA dose, occurring in two thirds of patients at 3000 mg x m(-2). Symptoms included blurring, flickering, fragmentation, alteration of colors, and contrast and mild photosensitivity, starting during the infusion and resolving completely, usually within 60 minutes. Visual acuity was unchanged but color discrimination was perturbed. Dose-dependent increases in PERG P50 implicit time by up to 23 ms returned toward baseline values within 90 minutes. Prominent transient changes on ERG included prolonged scotopic rod and 30-Hz flicker implicit times and reduced 30-Hz flicker amplitude. In the second trial, no clinically significant sustained effects were detected, although an increase in bright flash a-wave implicit time (P = 0.022) was seen on whole-group analysis. In vitro studies showed nonspecific phosphodiesterase inhibition by DMXAA. CONCLUSIONS: DMXAA induced acute, transient disturbance of retinal activity consistent with phosphodiesterase inhibition. No clinically significant cumulative effects were noted and most effects occurred at doses higher than those used in ongoing clinical trials (ClinicalTrials.gov numbers, NCT00856336, NCT00863733, and NCT00003697).