Clinical, radiographic, ultrasonographic and computed tomographic features of nonseptic osteitis of the axial border of the proximal sesamoid bones.
Authors: Vanderperren K, Bergman H J, Spoormakers T J P, Pille F, Duchateau L, Puchalski S M, Saunders J H
Journal: Equine veterinary journal
Summary
# Editorial Summary: Nonseptic Axial Osteitis of the Proximal Sesamoid Bones Axial border osteolysis of the proximal sesamoid bones (PSBs) is an uncommon condition in equine practice, traditionally associated with septic or traumatic injury, yet limited imaging guidance exists for the nonseptic form. A retrospective review of 18 cases diagnosed between 2007–2012 characterised the clinical and imaging features across multiple modalities: radiography (18 horses), ultrasonography (15 horses), computed tomography (9 horses), and contrast-enhanced CT (selected cases). Chronic unilateral lameness predominated—particularly in hindlimbs (14 of 18 cases)—whilst imaging revealed substantial variation in lesion severity; notably, CT imaging consistently demonstrated more extensive biaxial lysis (longer and deeper lesions) than radiographic appearance alone suggested, with contrast enhancement of the palmar/plantar ligament evident in some horses. Importantly, the degree of osteolysis bore no significant correlation with lameness grade or duration, suggesting that clinical severity cannot be predicted from imaging findings alone. Practitioners should recognise that radiography combined with ultrasonography provides adequate diagnostic confirmation in most cases, though CT adds valuable prognostic detail regarding true lesion extent—information potentially useful for owner counselling and monitoring, despite its apparent lack of correlation with acute lameness presentation.
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Practical Takeaways
- •Radiography combined with ultrasonography is sufficient for identifying nonseptic axial sesamoid osteitis in clinical practice, but CT should be considered if treatment planning requires detailed lesion mapping
- •Hindlimbs are affected 3.5 times more frequently than forelimbs in this condition; maintain diagnostic suspicion in chronically lame hindlimb cases unresponsive to standard treatments
- •Lesion severity on imaging does not predict lameness severity, so prognosis and management decisions should incorporate clinical response rather than relying solely on imaging extent
Key Findings
- •All 18 horses presented with chronic unilateral lameness (4 forelimb, 14 hindlimb) associated with axial border osteitis of proximal sesamoid bones
- •Radiography detected lysis in 17 of 18 horses (94%), while computed tomography revealed biaxial lysis in all 9 horses examined, with lesions significantly longer and deeper on CT than radiographs
- •Ultrasonography identified variable bone surface irregularities and palmar/plantar ligament echogenicity changes in all 15 horses examined
- •No significant relationship was found between the degree of osteolysis and lameness grade or duration, suggesting lesion severity does not predict clinical outcome