Page 183 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

158 CHAPTER 1

VetBooks.ir accessory carpal bone occur through acute single- is required to assess horses with a carpal fracture(s)
(Figs. 1.293, 1.294). Incomplete fractures may
impact overload, usually at speed, with the horse
landing on the affected limb in flexion. Fractures
generally occur in the frontal plane, although com- require diagnostic analgesia to localise the lameness
to the carpus. Nuclear scintigraphy will also highlight
minuted fractures also occur. incomplete fractures as well as subchondral bone
disease in the third carpal bone. MRI may also be of
Clinical presentation use in detailing carpal bone injury as well as associ-
Horses usually present acutely lame with carpal joint ated soft-tissue involvement.
effusion, although with incomplete fractures, lame-
ness may resolve quickly. Horses with carpal bone Management
fractures generally stand with the carpus in slight flex- Non-surgical management of carpal bone fractures
ion to reduce loading through the limb. Pain on pal- involves rest and controlled exercise, but surgical
pation and passive flexion is usually present, although management will provide a more definitive outcome
again, in incomplete fractures, further investigations even with incomplete fractures. Small fragments
may be required. Horses with comminuted or mul- may be removed/burred at the articular margin and
tiple carpal bone fractures may have overt limb defor- complete fractures may also be removed through
mity and carpal instability on manipulation. Horses careful dissection. Cases of subchondral bone dis-
with accessory carpal bone fractures usually stand ease without fulminant fracture are also debrided
semi-flexed with pain/swelling over the palmar aspect back to healthy margins. Surgical management of
of the carpus. Horses with involvement of the carpal slab fractures involves interfragmentary compres-
sheath may also present with a carpal sheath effusion. sion under arthroscopic guidance (Figs. 1.295,
1.296). Accessory carpal bone fractures are usually
Differential diagnosis managed conservatively, healing by fibrous union
Carpal OA; osteochondral fragmentation; luxation. (Figs. 1.297, 1.298). Removal of intra-articular
fragments may be required. Internal fixation has
Diagnosis been described but is difficult to perform due to the
Careful evaluation of a full radiographic series, includ- shape of the accessory carpal bone and large distrac-
ing oblique skyline projections of the carpal rows, tive forces on the bone.

1.293 1.294

Fig. 1.294
Lateromedial
radiograph of a
Thoroughbred
racehorse with a
Fig. 1.293 Dorsoproximal/dorsodistal oblique C3 radial facet slab
view of the carpus highlighting the distal row of fracture. (Photo
carpal bones. There is a complete, non-displaced courtesy Graham
fracture of C3. Munroe).