Deep erosions of the palmar aspect of the navicular bone diagnosed by standing magnetic resonance imaging.

The study investigates the challenges in diagnosing erosions in the palmar (flexor) aspect of a horse’s navicular bone and how standing magnetic resonance imaging (MRI) offers more accurate results. It further outlines the pathological characteristics of these erosions and emphasizes the poor chances of a horse returning to performance if these deep erosions occur.

Research Methodology

• The researchers studied cases where deep erosions of the palmar aspect of the navicular bone were diagnosed using a standing low field MRI.
• They examined the clinical details of each case, results of the diagnostic procedures, MRI features, and pathological findings.

Erosions in Horses Studied

• The MRI method allowed the researchers to diagnose deep erosions of the palmar aspect of the navicular bone in 16 mature horses, with 6 of them being bilaterally lame.
• 63% of these horses showed a sudden onset of lameness.
• Before the MRI was carried out, traditional radiography revealed uncertain changes in 7 horses.

MRI and Pathological Findings

• The MRI showed focal areas of intermediate or high signal intensity on T1-, T2*- and T2-weighted images and STIR images.
• These signals affected the dorsal aspect of the deep digital flexor tendon, the palmar fibrocartilage, subchondral compact bone, and medulla of the navicular bone.
• Post-mortem examinations confirmed erosions of the palmar aspect of the navicular bone in two horses.
• From a histological aspect, the lesions were characterized by localized degeneration of fibrocartilage with underlying focal osteonecrosis and fibroplasia. In addition, adjacent deep digital flexor tendons exhibited fibril formation and fibrocartilaginous metaplasia.

Outcomes and Prognosis

• Of the 16 horses studied, 44% or 7 horses had to be euthanized, and only one could work at its previous level.
• Based on these results, the researchers concluded that deep erosions of the palmar aspect of the navicular bone represent serious lesions that carry a poor prognosis for a horse to resume performance.
• The team suggested that earlier diagnosis of these erosive lesions might enable therapeutic intervention at an early stage, preventing their progression to deep erosive lesions.

Implications of the Study

• This study highlights the efficacy of standing low field MR imaging over conventional radiography for diagnosing deep erosions of the palmar aspect of the navicular bone.
• The research also presents valuable insights into the pathology of these erosions, providing veterinarians with better understanding to manage this condition.