Spontaneous fracture of the navicular bone in the horse.
Authors: Arnbjerg
Journal: Nordisk veterinaermedicin
Summary
Navicular bone fractures are rare but challenging injuries that present with acute, severe lameness disproportionate to visible swelling, accompanied by marked pain on coffin joint rotation. Arnbjerg's clinical analysis of three cases describes the underlying pathology: whilst radiographic evidence of the fracture persists throughout the horse's life without callus formation, healing occurs through fibrous tissue proliferation, with poor long-term outcomes driven by adhesions between the deep flexor tendon and fracture site, and potential secondary coffin joint degeneration. Conservative management combining full bar shoeing with clips and high calks, two months of box rest, and then gradual ridden rehabilitation over approximately six months proved successful in returning all three horses to full work. The key implication for practice is that navicular fractures warrant aggressive early immobilisation and shoeing support, followed by methodical, progressive loading rather than extended confinement—though clinicians should counsel owners that persistent lameness lasting months is typical, and that radiographic resolution will never occur. Understanding that the fracture line remains visible indefinitely whilst fibrous healing suffices for function helps distinguish true healing from radiographic persistence and manage owner expectations appropriately.
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Practical Takeaways
- •Navicular fractures present as acute severe lameness with pain on coffin joint rotation—distinguish from other navicular conditions by this acute presentation and diagnostic imaging
- •Full bar shoes with clips and high calks combined with controlled box rest and progressive rehabilitation can restore working capacity; expect ~6 months total recovery time
- •Persistent lameness often results from adhesions between deep flexor tendon and fracture site or coffin joint damage, not delayed healing—this influences prognosis and management expectations
Key Findings
- •Acute severe lameness without significant swelling is the primary clinical sign, with pronounced pain on coffin joint rotation
- •Lameness reduces considerably with rest but can persist for several years without treatment
- •Three horses treated with bar shoes, clips, high calks, and 2 months box rest followed by progressive rehabilitation regained full working capacity in approximately 6 months
- •Fracture healing occurs through fibrous tissue formation rather than callus formation, with radiographic fracture line persisting for life