Assessment of knee ossification timings: Development and validation of an ordinal scoring protocol for age estimation using medical imaging

ObjectivesAssessing skeletal maturity using epiphyseal and morphological features with modern, reliable evaluation protocols is crucial for human identification efforts and paediatric growth monitoring. This study aims to develop and validate a scoring system for knee skeletal development on post-mortem computed tomography (PMCT) and magnetic resonance imaging (MRI) acquired from Australian and New Mexican children.Materials & MethodsA protocol for the skeletal knee was developed on 30 PMCT and 30 T2-weighted MRI scans of subadults aged eight- to- 22 years. DICOM image stacks from a Brisbane children’s hospital and the New Mexico Decedent Image Database (NMDID) underwent multiplanar reconstruction and anatomical alignment. The protocol comprised a three- to- six stage scoring process at four epiphyseal fusion and seven maturity indicator sites. Three observers of varying experience levels assessed the images across three days, with reliability quantified using an intraclass correlation coefficient (ICC).ResultsThe protocol demonstrated high reliability and consistency, with excellent intraobserver agreement for CT (ICC = 0.985 (95 % CI: 0.93-1.00)) and MRI (ICC = 0.979 (95 % CI: 0.85-1.00)). Mean inter-observer reliability measures were good for CT (ICC = 0.886 (95 % CI: 0.75-0.95)) and MRI (ICC = 0.852 (95 % CI: 0.68-0.95)). The tibial tubercle demonstrated the most variability and long-bone epiphyseal union the leastConclusionsThis research presents a highly reproducible method for assessing skeletal development of the knee in subadults, aligned with modern imaging standards. The methodology will have application in forensic human identification, age confirmation and clinical growth assessmen

Multi-indicator Age Standards for Epiphyseal Union of Australian Children derived from Post-mortem Computed Tomography

After attending this presentation, attendees will gain an awareness of the temporal characterization of secondary ossification of the post-cranial skeleton in Australian subadults; and be informed of the possibilities associated with the development of a new Bayesian multi-indicator model for age estimation. The integrity of current techniques employed in forensic and clinical practice for estimating subadult age has been questioned due to complexities of reference collections, socio-environmental variation, and use of conservative statistical approaches. Developmental data collected from living Australian children under the Trauma Protocol at metropolitan Childrens Hospitals has led to the dissemination of re-calibrated single-variable age standards for the cranium, cervical spine and iliac crest using morphological approaches1. Updated, modality-specific developmental data has yet to be collected for epiphyses of the appendicular skeleton.In this study, PMCT scans conducted for triaging of forensic casework at the Victorian Institute of Forensic Medicine were acquired for 401 subadults (males: n=206, females: n=195) aged 2-25 years. DICOM datasets were viewed as multi-planar reconstructions, and 21 secondary ossification centers of the extremities scored using five-stage ordinal classification. Transition analysis was applied to elucidate age at transition between union states for each centre, and uni-indicator posterior distributions of age established for all sites. This study complements Scheuer and Black2, providing the first exclusive set of CT-specific age intervals for union and temporal maturity of each secondary ossification centre; and demarcates significantly earlier onset of ossification and attainment of final form compared to key literature. For example, the oldest Australian male to exhibit ‘non-union’ of the composite epiphysis of the proximal humerus is 12.4 years, compared to 18 years in Lisbon individuals3. Complete fusion of the distal humerus occurs as young as 12 years in males and all upper limb centres (except the clavicle) are fused by 20 years. In females, complete fusion of the femoral head occurs between 13-16 years, greater and lesser trochanters between 12-15 years; while lower limb centres are fused before 17 years.This study also showcase a statistical alternative using Bayesian clustering with a Dirichlet process mixture model to combine multiple sites for age estimation. Key results from the model average delineated six variables that highly contribute to model fit, while cluster analysis identifies four key developmental milestones which coincide with significant ossification activity in modern individuals. We also provide skeletal alternatives for substitution into the model, in the event of recovering isolated or fragmentary remains

Developing multi-indicator ossification standards for the knee to improve age estimation in contemporary subadults

This presentation will showcase updated imaging-specific growth and developmental data for the knee complex using a multivariable statistical approach, in a modern Australian population. The limitations of antiquated radiograph reference standards and impact of population variation on age estimates will be demonstrated through intra-and-inter-populationcomparisons.The estimation of skeletal age in forensic anthropology practice has importantapplications to medico-legal investigations. Understanding skeletal growth and development trends may assist in determining the age of unidentified human remains or age assessment in living individuals who lack documentation. This study aimed to document knee ossification timings in 1,200 subadults aged 8-22 years, using computed tomography (CT) and magnetic resonance imaging (MRI) scans acquired from Queensland Children’s Hospital (QLD), Adelaide Women’s and Children’s Hospital (SA) and the Victorian Institute of Forensic Medicine (VIC). Thin-slice data for each individual was cropped to the region of interest and viewed using multi-planar reconstructions in a DICOM viewer. An ordinal stage-based scoring approach was applied to score the development of 11 skeletal indicators of the femur, tibia and fibula, inspired by definitions provided in O’Connor et al1 and Roche et al2. Three scoring systems were used: a three-stage system for morphological development, a four-stage system for long-bone epiphyseal capping, and a five-stage system for epiphyseal union of the fibula, composite distal femur and proximal tibia. The protocol indicated high levels of repeatability, evidenced by good-to-excellent inter-and-intra-rater agreement (ICC: 0.96-1.0) for all indicators. Transition analysis was conducted to elicit maximum likelihood estimates for maturation across each stage, and age parameters were established with a multivariable Bayesian model in R.Preliminary results indicate that the appearance of non-epiphyseal maturity indicators commence between 9-10.5 years of age in males, and complete development before 22 years. Long-bone epiphyseal union commenced between 8.5 to 13.5 years and was complete as young as 16 years in males. Sexual dimorphism onset of development supports existing literature, with non-epiphyseal maturity indicators appearing from 8 years and complete fusionof the epiphyses recorded from 15 years. This study constitutes the first to employ nonstandard maturity indicators and standard epiphyseal growth plate sites, on three- dimensional structural imaging, to develop a multivariable, multi-indicator age estimation model using a Bayesian statistical approach.This presentation will also discuss similar developmental trajectories noted between living and postmortem data of the same population, while comparison to a matched United States population (n=478, aged 8 to 23) refutes error attributed to population variation

Implementing a new Clinical Skills Formative Assessment tool to support undergraduate student learning in Medicine

Background: Educators have witnessed changing and increased student expectations regarding the provision and frequency of feedback. This is driven by the recognition that feedback is inherent to the learning process, by allowing students to re-evaluate strategies and behaviours to optimize understanding of subject content, through which self-reflection feeds self-regulatory behaviour.Summary Of Work: This study involved the implementation of a novel formative assessment feedback tool within the clinical skills teaching of second-year undergraduate medical students. The Four Ps formative assessment tool (4Ps) centred around four pillars: Preparation, Participation, Performance and Professionalism. A criterion-referenced marking score for each pillar provided students with an overall mark, with a maximum of 12 points. Specific, task focussed written feedback was included to support self-monitoring by the students and disseminated at regular intervals via the learning management system.Summary Of Results: Evolution of the Four Ps tool was informed by student testimonials, qualitative evaluation data, clinical tutor feedback and reflective practice over a 12-month period, to develop an accessible, standardized, and personalised framework. Engagement in these self-regulatory processes sought to enhance students’ motivational beliefs and achievement of learning. Needs assessment of a large contingent of clinical tutors informed the data input tool allowing the development of standard feedback statements, to ensure consistency and equity for learners.Discussion And Conclusion: The 4Ps tool meets the needs of modern learners, who seek feedback that is consistent, varied in delivery, and personalised to encourage self-monitoring of clinical skills. Preliminary results indicate it has the potential to be a highly effective and valuable resource for both students and educators. Its implementation within a clinical skills curriculum can allow timely performance feedback, opportunities for learner self-reflection and increased engagement in the learning process. It provides a means to identify students requiring support through identification of knowledge and/or skill deficiencies and more broadly provides real-time curriculum review, evaluation of and calibration of small group teaching in large cohorts.Take Home Messages• We showcase the potential of a new formative assessment tool to respond to changing learner expectations, to provide feedback in clinical skills that is relevant, actionable, and aligned with the learning outcomes of the course