Page 182 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

Musculoskeletal system: 1.4 The forelimb 157

VetBooks.ir 1.290 1.291

Fig. 1.290 Dorsolateral/palmaromedial oblique Fig. 1.291 Lateromedial radiograph of a flexed
view of the left carpus of a horse with a smooth carpus demonstrating a chronic osteochondral
triangular-shaped osteochondral fragment at the chip fracture on the distal medial radius within the
dorsomedial margin of the middle carpal joint. antebrachiocarpal joint. (Photo courtesy Graham
There is bony modelling of the dorsodistal aspect Munroe).
of the radial carpal bone and associated soft-tissue
swelling.
CARPAL FRACTURES
1.292
Definition/overview
Fractures involving the carpal bones including slab
(frontal and sagittal configurations) and commi-
nuted fractures. ‘Chip’ fractures are dealt with in
the previous section (Osteochondral fragmentation).

Aetiology/pathophysiology
Carpal fractures usually result from a single over-
load injury or traumatic incident, although stress
adaptation of the bones, particularly the third carpal
bone, is involved in some fractures (e.g. slab fractures).
These latter fractures may be preceded by subchon-
dral bone sclerosis and lucency, with loss of overlying
articular cartilage as a result of repetitive loading,
and they tend to occur in the frontal plane through
the radial facet of the third carpal bone. Sagittal plane
Fig. 1.292 Arthroscopic view of the medial fractures are less common. Comminuted carpal bone
mid-carpal joint clearly showing a chronic distal fractures generally occur through acute trauma/
radiocarpal bone chip fracture prior to removal. impact and can involve more than one bone/carpal
(Photo courtesy Graham Munroe) row, leading to carpal instability. Fractures of the