Distal border synovial invaginations of the equine distal sesamoid bone communicate with the distal interphalangeal joint.

The research article investigates the communication pattern of synovial invaginations in the equine distal sesamoid bone, commonly known as the navicular bone, with other parts of the horse’s foot. The findings suggest that the invaginations are connected to the distal interphalangeal joint, more than they are to the navicular disease, thus challenging previous beliefs.

Objective of the Research

• The study focuses on understanding the communication pattern of synovial invaginations in the navicular bone with the distal interphalangeal joint and the navicular bursa.
• Conventional understanding suggests that these invaginations relate primarily to navicular disease. However, this study challenges this association, suggesting the invaginations have more interactivity with the distal interphalangeal joint.
• The research aims to evaluate the approach of using the status of these invaginations as an indicator of navicular disease in horse assessments.

Methods and Procedure

• The researchers used a prospective observational study involving 10 cadaveric limbs with radiographically apparent synovial invaginations.
• The limbs were randomly assigned to undergo either computed tomography arthrography or bursography imaging procedures using iopamidol, a contrast medium.

Findings and Results

• Results demonstrated that invaginations were filled with contrast medium in all five limbs exposed to distal interphalangeal arthrography, but no such medium filled invaginations in the limbs undergoing bursography.
• This suggests that the synovial invaginations in the navicular bone communicate more regularly with distal interphalangeal joints than with bursal regions implicated in navicular disease.

Conclusions and Implications

• Findings contradict current understanding that these invaginations are primarily linked to navicular disease. Instead, they might indicate distal interphalangeal arthropathy, also known as joint inflammation.
• Therefore, using synovial invaginations as a predictor for navicular disease may not be an accurate method.
• However, the study accepts that comorbidities, i.e., co-occurring diseases or conditions, are common in equine distal limb and enlarged synovial invaginations could be a part of limbs with primary navicular disease.
• Additional research is needed to further understand the relationship and possible co-dependencies between these different structures and conditions within the horse’s foot.