Summary
Objectives: Macroscopic studies have suggested a link between distal border synovial invaginations
of the navicular bone and the distal interphalangeal joint. However, many practitioners
consider that these invagi-nations are directly and solely related to navicular disease.
The objective was to investigate the communication pattern of these synovial invaginations
with the synovial compartments of the distal interphalangeal joint and the navicular
bursa, using minimally invasive imaging techniques.
Methods: In a prospective observational study, 10 cadaveric limbs with radiographically evident
distal border synovial invagi-nations were randomly assigned to computed tomography
arthrography or bursography groups, using iopamidol.
Results: In 5/5 limbs, contrast medium filled the invaginations following distal interphalangeal
arthrography. In the other five limbs, no contrast medium filled the invaginations
following bursography.
Clinical significance: Contrary to existing beliefs, these invaginations are more likely associated with
distal interphalangeal joint synovitis and may not be directly linked to primary navicular
bone pathology, but might reflect distal interphalangeal arthropathy. Therefore, the
rationale for assessment of these invaginations in stallion selection or pre-purchase
examinations as a predictive sign for navicular disease is questionable. Nonetheless,
comorbidities are frequent in the equine distal limb. Enlarged synovial invaginations
may also be seen in limbs with concomitant primary navicular disease. Further studies
are needed to elucidate possible inter-related pathological processes.
Keywords
Horse - navicular bone - arthrography - bursography