Page 157 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

132 CHAPTER 1

VetBooks.ir FETLOCK

SESAMOID BONE FRACTURES
adaptive remodelling due to exercise and tension
through the insertion of the suspensory ligament.
Definition/overview As such, the porosity of the bone may alter, leading
Fractures of the proximal sesamoid bone (PSBs) to a higher risk of failure.
include apical (<30% of the height of the bone),
mid-body, axial, basilar, abaxial and commi- Clinical presentation
nuted forms. Fractures can be uniaxial or biaxial Most PSB fractures result in acute-onset lameness
(Figs. 1.231–1.234). with swelling and focal pain on palpation. Effusion
of the fetlock joint may be present. In cases of biaxial
Aetiology/pathophysiology PSB fracture the horse is usually severely lame and
Fractures of the PSBs may be due to a single trau- on weight bearing may show evidence of severe fet-
matic incident, although evidence exists of stress lock drop.

1.231 1.232

Apical Mid-body

1.233 1.234

Basilar

Abaxial

Comminuted Axial
Figs. 1.231–1.234 Classification of fractures of the proximal sesamoid bone with representative radiographs:
1.231 – apical; 1.232 – mid-body; 1.233 – abaxial; 1.234 – basilar. Diagrams show only comminuted and axial
forms.