A description of the motion of the navicular bone during in vitro vertical loading of the equine forelimb.
Authors: van Dixhoorn I D E, Meershoek L S, Huiskes R, Schamhardt H C
Journal: Equine veterinary journal
Summary
# Editorial Summary Understanding how the navicular bone moves during weight-bearing has long been challenging, yet this motion may be fundamental to navicular disease pathogenesis. Using roentgen stereophotogrammetric analysis with tantalum pellet markers, van Dixhoorn and colleagues measured three-dimensional navicular bone kinematics in six equine forelimbs during vertical loading up to 2 kN, documenting movement patterns that were restricted to flexion and extension with negligible out-of-plane displacement. Whilst the navicular bone largely tracks with the coffin bone as the joint flexes—with flexion between these two bones showing high correlation (r = 0.97) to overall coffin joint motion—the researchers identified small but consistent relative movements between the navicular bone and coffin bone that were moderately correlated (r = 0.66) with joint flexion. These subtle motions, occurring within what appears to be a tightly constrained mechanical system, may represent a critical mechanism in navicular disease development, suggesting that even minor alterations in joint biomechanics or soft tissue support could accumulate to cause pathological change. For practitioners, this underscores the importance of early intervention in cases showing subtle joint instability or altered loading patterns, as the navicular apparatus appears vulnerable to micromotion-related damage rather than gross structural failure.
Read the full abstract on PubMed
Practical Takeaways
- •The navicular bone exhibits small but consistent independent motions relative to the coffin bone during weight-bearing; these micro-motions may be relevant to navicular disease pathogenesis and should inform therapeutic and farriery approaches
- •Understanding that the navicular bone's motion is primarily coupled to coffin joint flexion can help guide management strategies targeting joint stability and load distribution
- •In vitro findings suggest that interventions reducing excessive coffin joint flexion or stabilizing navicular-coffin bone interactions may be beneficial in navicular disease prevention or management
Key Findings
- •Navicular bone motion during vertical loading was limited to flexion/extension with no substantial out-of-plane movements
- •Flexion between navicular and coffin bone was small (r=0.66 correlation with coffin joint flexion) but consistent
- •Substantial flexion occurred between navicular bone and short pastern bone, highly correlated with coffin joint flexion (r=0.97)
- •Navicular bone generally follows coffin bone motion during loading, despite small independent movements that may contribute to navicular disease development