MR imaging of osteochondral grafts and autologous chondrocyte implantation

Surgical articular cartilage repair therapies for cartilage defects such as osteochondral autograft transfer, autologous chondrocyte implantation (ACI) or matrix associated autologous chondrocyte transplantation (MACT) are becoming more common. MRI has become the method of choice for non-invasive follow-up of patients after cartilage repair surgery. It should be performed with cartilage sensitive sequences, including fat-suppressed proton density-weighted T2 fast spin-echo (PD/T2-FSE) and three-dimensional gradient-echo (3D GRE) sequences, which provide good signal-to-noise and contrast-to-noise ratios. A thorough magnetic resonance (MR)-based assessment of cartilage repair tissue includes evaluations of defect filling, the surface and structure of repair tissue, the signal intensity of repair tissue and the subchondral bone status. Furthermore, in osteochondral autografts surface congruity, osseous incorporation and the donor site should be assessed. High spatial resolution is mandatory and can be achieved either by using a surface coil with a 1.5-T scanner or with a knee coil at 3 T; it is particularly important for assessing graft morphology and integration. Moreover, MR imaging facilitates assessment of complications including periosteal hypertrophy, delamination, adhesions, surface incongruence and reactive changes such as effusions and synovitis. Ongoing developments include isotropic 3D sequences, for improved morphological analysis, and in vivo biochemical imaging such as dGEMRIC, T2 mapping and diffusion-weighted imaging, which make functional analysis of cartilage possible

Verbal and nonverbal indices of learning during problem-based learning (PBL) among first year medical students and the threshold for tutor intervention

Background: During problem-based learning (PBL), students brainstorm on a problem, generate hypotheses and formulate learning objectives. Certain verbal and non-verbal expressions are used by students in response to specific learning issues. Aims: This study examines the use of these expressions as indices of the learning taking place and the tutors’ threshold to intervene. Methods: Common verbal expressions used by students during PBL were identified and scored on a Likert scale to indicate the learning taking place. These expressions were categorised into the following groups of learning interactions: exploratory questioning, cumulative reasoning and handling conflicts relating to learning. The tutor's threshold for intervention was also scored on a Likert scale. Means for each learning interaction and observed non-verbal expressions were used to construct bar charts for comparison. Results: When the learning interactions involve exploratory questioning or cumulative reasoning, students tend to score high on learning and tutors have high threshold for intervention. When the learning interactions involve handling conflicts relating to knowledge, students score high on learning, but teachers have a low threshold for intervention. Conclusion: Verbal and non-verbal expressions from students during PBL are useful indices of learning and can be used to help tutors decide when and when not to intervene