Abstract :
[en] This descriptive study aimed to compare the magnetic resonance appearance of the distal
interphalangeal joint articular cartilage between standing weight-bearing and non-weightbearing conditions. Ten forefeet of live horses were scanned in a standing low-field magnetic resonance system (0.27 T). After euthanasia for reasons unrelated to the study, the
non-weight-bearing isolated feet were scanned in a vertical positioning reproducing limb orientation in live horses. The same acquisition settings as during the weight-bearing examination were used. Thickness and cross-sectional area of the distal interphalangeal articular
cartilage and joint space were measured on tridimensional T1-weighted gradient echo high
resolution frontal and sagittal images at predetermined landmarks in both conditions and
were compared using a linear mixed-effects model. Frontal images were randomized and
submitted to 9 blinded readers with 3 different experience levels for identification of weightbearing versus non-weight-bearing acquisitions based on cartilage appearance. Weightbearing limbs had significantly thinner distal interphalangeal cartilage (p = 0.0001) than nonweight-bearing limbs. This change was greater in the distal phalanx cartilage than that of the
middle phalanx. Blinded readers correctly identified 83% (range 65 to 95%) of the images
as weight-bearing or non-weight-bearing acquisitions, with significantly different results
observed among the different readers (p < 0.001) and groups (p < 0.001). These results indicate that distal interphalangeal articular cartilage and particularly cartilage of the distal phalanx thins when weight-bearing compared to the non-weight-bearing standing postmortem
conditions and suggest that cartilage abnormalities may be more difficult to identify on
weight-bearing standing magnetic resonance imaging.
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