Magnetic resonance imaging findings in the carpus and proximal metacarpal region of 50 lame horses.
Authors: Nagy A, Dyson S
Journal: Equine veterinary journal
Summary
# Editorial Summary: MRI Findings in Carpal and Proximal Metacarpal Lameness Between 2003 and 2010, Nagy and Dyson reviewed 72 MRI studies from 50 lame horses presenting with localised forelimb lameness in the carpus and proximal metacarpal region, comparing findings with available radiographs, ultrasound and scintigraphy where possible. Decreased signal intensity within the medial carpal bones and proximomedial metacarpal bones emerged as the most prevalent primary abnormality (29 cases), whilst less common but significant findings included syndesmopathy between the second and third metacarpal bones (9 horses), palmar cortical lesions of the third metacarpal bone (6 horses), suspensory ligament pathology with associated osseous changes (4 limbs), and ligamentous injuries between the carpal and metacarpal bones (4 limbs). MRI identified a considerably broader spectrum of lesions across horses from diverse disciplines than conventional imaging modalities, revealing injury distributions that notably diverged from previously published data. For practitioners managing persistent or atypical forelimb lameness—particularly where radiography and ultrasound appear inconclusive—this work underscores MRI's diagnostic value in detecting bone marrow pathology, subtle ligamentous injuries, and palmar cortical changes that would otherwise remain unidentified and untreated.
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Practical Takeaways
- •MRI should be considered for lame horses with carpal or proximal metacarpal lameness when conventional imaging is inconclusive, as it detects lesions (especially bone marrow and ligament changes) that radiographs and ultrasound miss
- •Medial carpal bone lesions and metacarpal bone signal changes are the most commonly encountered abnormalities in this region—develop familiarity with their appearance on MRI and their clinical significance
- •The diversity of lesions detected across different disciplines and age groups suggests carpal/metacarpal injury patterns may vary by work type; correlate MRI findings with use history and biomechanical stresses specific to each horse's discipline
Key Findings
- •Decreased signal intensity in carpal and/or proximomedial metacarpal bones was the most common finding (n=29 of 72 studies)
- •MRI identified lesions not detected by conventional imaging modalities (radiography, ultrasonography, scintigraphy) across multiple work disciplines
- •Syndesmopathy between second and third metacarpal bones occurred in 9 horses, with suspensory ligament abnormalities and associated palmar cortex lesions in 4 limbs
- •Distribution of injury types differed considerably from previous studies, suggesting breed, age, and discipline-specific variations in carpal/metacarpal pathology