Joint Stress Analysis of the Navicular Bone of the Horse and Its Implications for Navicular Disease.

This research paper evaluates the stress distribution on a horse’s navicular bone and how its structure can influence joint stress, potentially leading to severe navicular disease. The study gives insight into why horses with certain navicular bone shapes might be more susceptible to degenerative navicular disease.

Study Objectives

• The main goal of this study was to examine how the stress distribution across the navicular bone, which is found within a horse’s hoof, is affected by the bone’s morphological differences.
• The study sought to understand how the joint forces, when standardized to the Deep Flexor Tendon’s (DDFT) force, result from force and moment equilibria. This understanding is derived from the morphological parameters discerned from mediolateral radiographs.

Methodology

• An analysis of the stress distribution on the navicular bone’s articular surface was done based on the moment equilibrium of stress vectors around the centre of pressure.
• The research particularly explored how the ratio of the DDFT’s proximal to distal moment arms, the navicular bone’s proximo-distal position, and extent influence the joint forces and the stress distribution.

Findings

• It was found that when the moment arms are equal and the bone is situated more proximally, the joint force vector stems from the joint surface centre, creating an evenly distributed joint load.
• If the navicular bone is in a more distal position with a longer distal moment arm, the joint force is near the distal edge. Here, peak joint stress is experienced.
• The study noted that degenerative navicular disease, which results in lameness and pathological alterations in the bone’s distal portion in sport horses, is likely to be more severe in horses with wedge-shaped navicular bones than in those with square-shaped bones.

Conclusion

• Overall, the research brought to light important considerations on how the structure of the navicular bone can affect joint forces and stress distributions in horses.
• These findings could help in the prognosis and treatment of degenerative navicular disease in horses, particularly sport horses, potentially leading to improved care and welfare of these animals.