Analysis of Forces Acting on the Equine Navicular Bone in Normal and Dorsiflexed Positions
Authors: Kaitlyn C Ruff, Michelle L. Osborn, E. Uhl
Journal: The FASEB Journal
Summary
# Editorial Summary: Forces Acting on the Equine Navicular Bone in Normal and Dorsiflexed Positions Navicular disease remains one of equine practice's most frustrating chronic conditions—readily managed but rarely cured—prompting researchers to investigate whether a biomechanical approach could better explain how the disease develops. Ruff and colleagues used three-dimensional computed tomography reconstructions of equine forelimbs to perform free-body analysis, directly comparing the forces acting on the navicular apparatus when the foot was positioned normally versus in a dorsiflexed posture. The dorsiflexed position significantly increased tension in the deep digital flexor tendon, creating greater compressive loading on the navicular bone itself, whilst simultaneously tightening the impar and suspensory ligament attachments and increasing stress at their entheses. These biomechanical changes align precisely with the pathological features seen in navicular disease: bone lesions from excessive compression and osteophyte formation along the ligamentous attachment sites. For practitioners, this work strongly suggests that therapeutic strategies should prioritise reducing forelimb overloading and restoring normal foot mechanics through rehabilitation, rather than focusing solely on palliative measures—implying that many cases may be amenable to meaningful long-term improvement if the underlying mechanical dysfunction is addressed.
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Practical Takeaways
- •Managing navicular disease should focus on reducing forelimb overload and preventing habitual dorsiflexion through farrier and training modifications
- •Understanding that navicular lesions result from biomechanical overload rather than primary bone pathology supports conservative, load-management approaches over invasive interventions
- •Rehabilitation protocols should aim to restore normal foot mechanics and weight distribution to reduce chronic stress on the navicular apparatus
Key Findings
- •Dorsiflexed foot position increases deep digital flexor tendon tension, creating greater compressive force on the navicular bone
- •Dorsiflexion increases tension on impar and suspensory ligament attachments, explaining osteophyte formation at entheses
- •Chronic forelimb overloading induces habitual dorsiflexion, which drives pathomechanical changes characteristic of navicular disease
- •A pathomechanical treatment approach targeting reduction of dorsiflexion and forelimb loading offers potential therapeutic benefit