Manon W J Peeters 1, Stephan Ott 2, Elisabeth van Veggel 3, Dagmar Berner 1, Melanie Perrier 1
Background
Injuries to the palmar or plantar ligaments of the PL-PIPJ are infrequently reported in equine lameness diagnostics, and their clinical significance remains unclear. These ligaments play a role in stabilizing the proximal interphalangeal joint and preventing hyperextension. With low-field MRI being widely used for soft tissue imaging in equine practice, this study aimed to evaluate the visibility of these ligaments on MRI, characterize the imaging findings of desmitis, and explore correlations with clinical lameness.
Methods
This retrospective case series included 29 horses from three institutions who underwent low-field MRI of the foot or pastern. The study assessed desmitis in the axial and abaxial palmar/plantar ligaments, and the distal and proximal entheses of the digital annular ligaments. Lameness was scored using the AAEP scale, and MRI findings were reviewed by a board-certified radiologist, who graded visibility and pathology severity of the ligaments.
Results
MRI revealed desmitis as the primary finding in 45% of cases. The axial palmar/plantar ligaments were well-visualized in most cases, but the abaxial structures were poorly delineated, with only 5% clearly identifiable. Desmitis was commonly associated with increased ligament size and signal intensity, especially in the abaxial structures, which also frequently exhibited periligamentous oedema (74%) and enthesophyte formation (33%). In bilateral examinations, 73% of horses showed contralateral limb involvement. Most affected limbs exhibited moderate to severe increases in ligament cross-sectional area and signal intensity.
Limitations
The retrospective design, lack of standardized imaging protocols, and absence of histopathological confirmation limit the study. Inconsistent lameness assessment and diagnostic anesthesia protocols also hinder precise correlation of imaging findings with clinical signs. The inability to consistently differentiate between adjacent small ligaments further complicates diagnostic accuracy.
Conclusions
Desmitis of the PL-PIPJ can be a significant cause of lameness and should not be overlooked during low-field MRI evaluations. Periligamentous oedema is a key indicator of pathology in abaxial ligaments. Accurate diagnosis depends on identifying both increased ligament size and signal intensity, best seen on T2-weighted images. Improved imaging protocols and prospective studies are necessary to validate these findings and enhance clinical interpretation.
T1W transverse image (A), T2W FSE transverse image (B) and STIR transverse image (C) at the level of the distal aspect of the proximal phalanx, lateral is to the left, obtained using the 0.27 Tesla magnetic resonance system images obtained on a standing horse. There is marked increased cross-section of the lateral (circle) aspect of distal digital annular ligament (DDAL) and mild increase in cross-section of the medial aspect of DDAL (dotted circle), both showing mild increase in signal intensity in the T2W FSE and STIR sequences. New bone formation is evident at the lateral origin of the DDAL (arrow). Note that the ligaments are not well visualised in T1W images (A), likely due to magic angle artefact within these ligaments.
How did we do?
Disclaimer: The summary generated in this email was created by an AI large language model. Therefore errors may occur. Reading the article is the best way to understand the scholarly work. The figure presented here remains the property of the publisher or author and subject to the applicable copyright agreement. It is reproduced here as an educational work. If you have any questions or concerns about the work presented here, reply to this email.
