The collateral ligaments of the distal interphalangeal joint: magnetic resonance imaging and post mortem observations in 25 lame and 12 control horses.

The research focuses on using MRI (Magnetic Resonance Imaging) to diagnose injuries in horses’ collateral ligaments (CLs) of the distal interphalangeal (DIP) joint. The MRI results are then compared to post-mortem histological examinations to evaluate the effectiveness and reliability of MRIs.

Methodology

• The study involves two groups of horses: one group (Group N) of 12 horses free from lameness and another group (Group L) of 25 horses suffering from foot-related lameness.
• Both of these groups are subjected to MRI and post-mortem examinations for comparison.
• The MRI images obtained are graded based on their clarity and quality.
• Post-mortem histological examinations of different sections of the CLs are conducted, and each ligament is assigned a score based on its condition.
• Scintigraphic images (a type of imaging that uses radioactive substances) from lame horses are also evaluated.

Results

• In group N, 25 CLs were deemed normal on both MRI images and histology. However, discrepancies occurred where two ligaments showed minor abnormalities on MRI but were histologically normal, and two showed no abnormalities on MRI but exhibited abnormal histology.
• In Group L, similar disparities were noticed. Although 18 ligaments were normal in both MRI and histology, 54 abnormal ligaments were confirmed by both methods, but 13 appeared normal in MRI but were abnormal histologically.
• The study also observed lesions in the CLs, suggesting a primary degenerative process taking place. These were characterized by fibrocartilaginous metaplasia and development of multiple interconnected fissures within the degenerated collagen in severe cases.
• There was an association between increased radioactive substance uptake in scintigraphic imaging and a higher histological score, indicating a worsening condition.

Conclusions

• The research found that high-field MRI is reasonably reliable for detecting lesions of the CLs of the DIP joint in horses, but it might underestimate their prevalence based on the discrepancies observed with histological examinations.
• The primary degenerative process of collateral ligament injury was identified, which could explain the lack of response to conservative treatment. This finding suggests a need for therapeutic approaches that promote regeneration.