Magnetic resonance imaging findings in the equine deep digital flexor tendon and distal sesamoid bone in advanced navicular disease--an ex vivo study.
Authors: Busoni, Heimann, Trenteseaux, Snaps, Dondelinger
Journal: Veterinary radiology & ultrasound : the official journal of the American College of Veterinary Radiology and the International Veterinary Radiology Association
Summary
Advanced navicular disease produces characteristic changes in both soft tissue and bone that are now clearly identifiable on MRI, as demonstrated in this ex vivo study of 13 postmortem specimens scanned at 1.5 Tesla and subsequently dissected for correlation with gross and histological findings. Deep digital flexor tendon lesions were detected in 12 specimens and classified into distinct patterns—core lesions, dorsal lesions, dorsal abrasions, and parasagittal splits—predominantly located at the distal sesamoid level and proximal podotrochlear bursa recess, with pathological examination confirming these represented areas of fibre disruption, oedema, haemorrhage, and plasma extravasation rather than simple degeneration. All distal sesamoid bones showed abnormal marrow signal intensity reflecting a shift from normal fat content towards fluid accumulation, with histology revealing bone marrow oedema, haemorrhage, necrosis, fibrosis, trabecular disorganisation, and focal cyst formation. Understanding these imaging-pathological correlations provides practitioners with a foundation for interpreting MRI findings in navicular cases, though the ex vivo nature of this work means clinical application requires validation in living horses where soft tissue mechanics and perfusion differ considerably. For farriers, veterinarians, and rehabilitation specialists managing navicular disease, these findings underscore the complexity of the condition beyond radiographic changes and highlight why advanced imaging has become essential for accurate diagnosis and prognosis.
Read the full abstract on PubMed
Practical Takeaways
- •MR imaging reliably identifies DDFT pathology in navicular syndrome, particularly lesions at the distal sesamoid level, supporting its use for diagnostic confirmation before treatment decisions
- •Distal sesamoid bone marrow changes are consistent findings in navicular disease and may indicate the extent of degenerative changes affecting prognosis
- •Understanding the correlation between MR signal patterns and specific histologic lesions (edema, necrosis, cyst formation) helps interpret clinical MR images and explain lameness severity
Key Findings
- •MR imaging detected tendonous abnormalities in 12 of 13 DDFTs, with most lesions located at the distal sesamoid bone level and proximal podotrochlear bursa
- •DDFT lesions were classified as core lesions, dorsal lesions, dorsal abrasions, and parasagittal splits, characterized by fiber disturbance, edema, hemorrhage, and plasma-like material
- •Bone marrow signal alterations occurred in all distal sesamoid bones due to decreased fat content and increased fluid content, with histologic findings of edema, hemorrhage, necrosis, fibrosis, cyst formation, and trabecular disorganization