Page 217 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

192 CHAPTER 1

VetBooks.ir Diagnosis Where findings are inconclusive, a comparison
with the contralateral limb can be helpful. Recent
Flexion of the tarsus may exacerbate the lameness.
Some improvement in lameness may be anticipated
(Fig. 1.372) and CT of the hock and both modali-
following intra-articular analgesia, but, diagnostic advances in imaging have allowed for both MRI
regional analgesia is contraindicated in any horse ties may be useful where more conventional imag-
suspected of sustaining a fracture. Radiography is ing has not yielded a diagnosis. In the past, CT and
the most commonly used imaging modality, but not MRI of this region required general anaesthesia but
all fractures are immediately diagnosed and special advances in the motion correction software associ-
views such as flexed lateromedial, skyline view of ated with standing, low-field MRI mean that in a
the calcaneus, and modified oblique views may cooperative horse diagnostic MR images can be
be necessary (Figs. 1.369, 1.370). Occasionally, acquired without general anaesthesia.
a non- displaced fracture may not be radiographi-
cally apparent until demineralisation has occurred. Management
In these cases, repetition of the radiographs is Fractures of the lateral malleolus are best treated sur-
recommended within 14 days from injury, and in gically by arthroscopic removal of small fragments
some cases again after a further 14 days. Stress radio- (<1 cm). Repair of larger fragments, by internal fixa-
graphs may be helpful to diagnose instability of the tion or, if fragmented, through an arthrotomy can be
tarsal joints. Gamma scintigraphy can be beneficial successful. Conservative management of minimally
in horses with mild or bilateral hindlimb lameness displaced small fragments can also be considered.
and in cases where fractures are not demonstrated Arthroscopic removal is the treatment of choice
radiographically (Fig. 1.371). Ultrasonography is for small fragments that have fractured off the troch-
useful to help diagnose concurrent soft-tissue injury. lear ridges. Large fresh fractures may be amenable to

1.369 1.370

Fig. 1.370 Dorsoplantar flexed oblique radiograph
of the sustentaculum tali of the calcaneus showing
fragmentation and bony reaction of the medial edge
following a kick to the inside of the hock. (Photo
courtesy Graham Munroe)

Fig. 1.369 Plantarolateral/dorsomedial oblique
radiograph of a hock showing a fracture of the
sustentaculum tali of the calcaneus as a result of a kick
injury involving the tarsal sheath (arrow).