Three-dimensional anatomical description of the microarchitecture of the distal sesamoid bone in healthy and navicular syndrome-affected horses by computed microtomography.
Authors: P. Salinas, Matías Vergara, Danae Tapia
Journal: Anatomical record
Summary
Navicular syndrome remains a significant challenge in equine practice, traditionally understood as a vascular problem but now recognised as fundamentally biomechanical—arising from chronic overload of the deep digital flexor tendon and progressive degeneration of the distal sesamoid bone. Conventional imaging (radiography, scintigraphy, ultrasonography) cannot detect the early microstructural changes that precede clinical signs, limiting diagnostic sensitivity and intervention windows. Using micro-computed tomography on sesamoid bone samples from four affected and four control horses, Salinas and colleagues quantified three-dimensional trabecular architecture, measuring parameters including bone volume, density, trabecular thickness and separation, porosity, and connectivity. Horses with navicular syndrome demonstrated substantially compromised microarchitecture—lower bone volume and trabecular density, thinner and more widely separated trabeculae, increased porosity, and reduced connectivity—whilst healthy horses exhibited strong positive correlations between volume and density with well-integrated trabecular networks. The significant microstructural reorganisation identified by micro-CT represents pathological adaptation rather than simple bone loss, with quantifiable metrics (trabecular thickness, separation, and porosity) potentially serving as early diagnostic biomarkers before radiographic changes become apparent, though larger longitudinal studies are needed to establish clinical utility in practice.
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Practical Takeaways
- •Micro-CT imaging can detect early microarchitectural changes in the distal sesamoid bone before conventional imaging shows pathology, potentially enabling earlier intervention in navicular syndrome
- •Quantifiable metrics from micro-CT (trabecular thickness, separation, porosity) may become useful biomarkers for monitoring disease progression and treatment response in navicular cases
- •Current diagnostic limitations of radiography, ultrasound, and scintigraphy mean early-stage navicular syndrome changes in bone structure are being missed—this technique warrants clinical validation as a more sensitive diagnostic tool
Key Findings
- •Horses with navicular syndrome showed significantly lower bone volume, trabecular density, thickness, and connectivity compared to healthy controls
- •Affected horses exhibited increased trabecular separation, porosity, and anisotropy indicating pathological microarchitectural reorganization
- •Micro-CT identified disease-specific microstructural changes including quantifiable metrics (thickness, separation, porosity) not detectable by conventional radiography, scintigraphy, or ultrasonography
- •Healthy horses demonstrated strong positive correlations between bone volume and density with well-connected trabecular architecture, while affected horses showed compensatory trabecular consolidation and reduced trabecular numbers