46TH
ANNUAL
CONGRESS
OF
THE
SAEVA
SKUKUZA
16-‐20
FEBRUARY
2014
13
An update on axial sesamoiditis in
the horse
Le Roux C1* and Carstens A1
1
Section Diagnostic Imaging, Department of Companion Animal Clinical Studies, Faculty of Veterinary
Science, University of Pretoria, Onderstepoort 0110.
Abstract
Axial osteitis of the proximal sesamoid bones in the horse is described as a rare
condition, with approximately 20 reported cases. The cause remains unknown and
speculative, with vascular, infectious, and traumatic aetiologies implicated. It may be
infectious or non-infectious. It is specifically associated with injury of the
intersesamoidean ligament (ISL), also known as the palmar or plantar ligament. The
imaging findings are generally rewarding. Radiographs remain the foundation and
radiographic changes are typical, if not pathognomonic, for axial osteitis. Lesions
consist of bone lysis at the apical to mid-body axial margins of the PSBs, although the
entire axial border can be involved, with variable degrees of joint effusion.
Radiographic technique warrants careful attention to make a diagnosis, and exposure
factors may need to be adjusted. Perineural, intra-articular and intra-thecal
anaesthesia does not seem to provide consistent improvement of lameness in these
cases, with literature reporting opposing findings. Ultrasonographic findings may
include digital flexor sheath effusion, loss of the normal fibre structure of the ISL at
its attachment to the PSBs, altered and abnormal echogenicity or change in thickness
of the ISL, and irregular hyperechoic cortical margins of the axial margins of the
PSBs. Scintigraphy and computed tomography, although not necessary to make a
diagnosis, may add valuable information regarding the location and extent of lesions.
Unfortunately the prognosis remains guarded to poor for return to athletic function.
The focus of this paper is a brief review of the proposed aetiopathogenesis, a
summary of the literature findings and the notable diagnostic imaging features,
including radiography, ultrasonography, and scintigraphy and computed tomography.
An update on axial sesamoiditis in the horse
Axial osteitis, or sesamoiditis, of the proximal sesamoid bones (PSBs) in the horse is
described as a rare condition, with approximately 20 reported cases (Dabareiner et
al. 2001; Sedrish et al. 1996; Formston & Serth 1968; Wisner et al. 1991; Lawrence &
Fraser 2013; Sherman et al. 2006). The cause remains unknown and speculative
(Sherman et al. 2006). It is considered as a separate clinical entity from the typical
more abaxial presentation of proximal sesamoiditis, as it is specifically associated
with injury of the intersesamoidean ligament (ISL), also known as the palmar or
plantar ligament (Dabareiner et al. 2001; Richardson & Dyson 2011). Lameness is
usually more severe (grade 3/5 and more) in axial osteitis. In contrast, lameness from
abaxial sesamoiditis is comparatively rare, usually only occurring after hard work, and
is associated radiologically with widened abaxial vascular channels (the significance of
which is still debated) (Richardson & Dyson 2011). The ISL along with the PSBs form
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