Chondrosesamoidean ligament enthesopathy: Prevalence and findings in a population of lame horses imaged with positron emission tomography.
Authors: Norvall Amy, Spriet Mathieu, Espinosa Pablo, Ariño-Estrada Gerard, Murphy Brian G, Katzman Scott A, Galuppo Larry D
Journal: Equine veterinary journal
Summary
# Chondrosesamoidean Ligament Enthesopathy: An Emerging Diagnosis in Equine Foot Lameness Positron emission tomography (PET) imaging with 18F-sodium fluoride has revealed increased metabolic activity at the chondrosesamoidean ligament (ChSL) attachment on the distal phalanx in lame horses, yet the prevalence and clinical significance of this lesion remain poorly characterised. Norvall and colleagues retrospectively analysed 56 feet from 30 horses that underwent concurrent PET and CT imaging between 2016 and 2017, identifying increased 18F-NaF uptake at the ChSL attachment site in 20 feet (36%). Notably, ChSL enthesopathy was the primary lesion in only three horses, whilst the remaining cases featured concurrent pathology including navicular bone changes (13 feet) and ipsilateral palmar process lesions (9 feet), though no statistically significant association existed between these conditions. Importantly, foot lameness was significantly associated with ChSL enthesopathy, yet initial CT detection of this lesion was poor—identified prospectively in just one foot and retrospectively recognised in five additional feet only after PET results were known. These findings suggest ChSL enthesopathy warrants greater clinical attention as a contributor to equine foot pain, with careful assessment of the axial borders of the palmar processes on cross-sectional imaging essential for diagnosis, though practitioners should recognise that this lesion frequently occurs alongside other distal phalangeal pathology rather than in isolation.
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Practical Takeaways
- •PET imaging reveals chondrosesamoidean ligament enthesopathy in a substantial portion of lame horses, suggesting it may be an underrecognized cause of foot pain in clinical practice
- •When evaluating foot pain cases, carefully examine the axial borders of the palmar processes on CT or radiographs as this lesion is easily missed on standard imaging
- •ChSL enthesopathy often occurs alongside other foot pathology but can be the primary lesion, so comprehensive imaging of the entire foot is warranted in lame horses
Key Findings
- •14 of 30 horses (35.7%) showed increased 18F-NaF uptake at the chondrosesamoidean ligament attachment on distal phalanx
- •ChSL enthesopathy was significantly associated with foot lameness (P<0.05)
- •Lesion was the primary abnormality in only 3 horses but commonly co-occurred with navicular bone uptake (13 feet) and palmar process uptake (9 feet)
- •CT imaging initially identified the lesion in only 1 foot but retrospective review found it in 5 additional feet after PET findings