Distal border fragments of the equine navicular bone: association between magnetic resonance imaging characteristics and clinical lameness.

The research focused on understanding the connection between fragments in the distal border of the equine navicular bone, as observed through MRI, and clinical lameness in horses. The study found no strong correlation between the distal border fragments and the severity of lameness.

Research Rationale and Methodology

• The research was aimed at unraveling the clinical significance of distal border fragments of the navicular bone in horses, as there was an increasing detection of these fragments due to enhanced MRI capabilities.
• A retrospective study was conducted. In a range of slightly more than two years (March 2006 – June 2008), archived MRI studies and medical records associated with MRI scans of horse foot were investigated.
• The sample covered horses where distal border fragments of the navicular bone were visible in MRI scans. Horses without these fragments were not considered in the study, therefore totalling 453 horses (874 limbs).
• Studied parameters included the location, size, and frequency of the fragments, and the level of the horses’ lameness. Statistical methods of the confidence interval comparison and linear regression analysis were used to test the relationship between fragments, lameness, and the severity of lameness.

Key Findings

• Fragments were identified in 13.25% of horses and 10.3% of limbs. The fragments were distributed bilaterally and unilaterally among horses in a 50-50 split. Most fragments were found on the lateral (62.2%) side of the distal border of the navicular bone, while some were found on the medial side (8.89%) or both sides (28.9%).
• Contrary to initial hypothesis, there was no distinct association between the presence of a fragment and the probability of a horse being classified as lame.
• The study also found no glaring difference in fragment volume across varying levels of lameness severity.
• Horses with fragments on both the medial and lateral sides showed a slightly increased probability of being categorized as lame.

Final Observations

• In conclusion, the research found that the distal border fragments of the navicular bone, as seen in equine MRI studies, are unlikely to be directly related to existing lameness in horses.
• Although this observation gives noteworthy insights, the significance of distal border fragments in the diagnosis and treatment of lameness requires further study. This will include understanding why horses with fragments on both sides of the bone have slightly higher chances of lameness.