Objectives

To compare regional differences in subchondral trabecular structure using high-resolution MRI in meniscus-covered/meniscus-uncovered tibia in cadaveric knees with intact/torn menisci.

Materials and methods

3D proton density CUBE MRI of 6 cadaveric knees without significant osteoarthritis (OA) was acquired, 0.25-mm resolution. Menisci were evaluated and classified intact or torn. MR data were transferred to ImageJ program to segment tibial 3D volume of interest (VOI). Data was subdivided into meniscus-covered/meniscus-uncovered regions. Segmented VOI was classified into binary data, trabeculae/bone marrow. The trabecular bone data was used to measure MR biomarkers (apparent subchondral plate-connected bone density (adapted from spine MR), apparent trabecular bone volume fraction, apparent mean trabecular thickness, apparent connectivity density, and structure model index (SMI)). Mean value of parameters was analyzed for the effects of meniscal tear/tibial coverage.

Results

Nine torn menisci and 3 intact menisci were present. MR measures of bone varied significantly due to meniscal coverage/tear. Subchondral plate-connected bone density under covered meniscus regions increased from 10.9 to 23.5% with meniscal tear. Values increased in uncovered regions, 19.3% (intact) and 32.4% (torn). This reflects higher density when uncovered (p = 0.048) with meniscal tear (p = 0.007). Similar patterns were found for trabecular bone fraction (coverage p < 0.001, tear p = 0.047), trabecular thickness (coverage p = 0.03), connectivity density (coverage p = 0.002), and SMI (coverage p = 0.015).

Conclusion

Quantitative trabecular bone evaluation emphasizes intrinsic structural differences between meniscus-covered/meniscus-uncovered tibias. Results offer insight into bone adaptation with meniscal tear and support the hypothesis that subchondral bone plate-connected bone density could be important in early subchondral bone adaptation.

Speech disfluency refers to the errors, pauses, or repetitions in speech production. Co-speech gestures are known to help resolve disfluency, suggesting a metacognitive involvement. Here we ask whether (1) disfluencies and gestures act as metacognitive cues in speech, and (2) they have different functions in conversational vs. non-conversational settings. Fifty participants responded to trivia questions, and rated their confidence in their answers (i.e. metacognitive judgement), either with a visible or a non-visible listener. They audibly elaborated on their answers during which we measured the frequency and type of disfluencies and co-speech gestures. We predict confidence ratings to change as a function of the rate of disfluency and the gestures produced by the participants. We also expect the rate of disfluencies and gestures change depending on the conversational setting. Our findings will contribute to understanding the multimodal nature of language and the role of metacognition in speech and gesture production.