Page 153 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

128 CHAPTER 1

VetBooks.ir Comminuted P1 fractures without an intact strut greater soft-tissue dissection is required with
abaxial compared with axial fragments. Uniaxial
are serious injuries and have a guarded prognosis
for survival and are often euthanased. Salvage of the
fixation or treated conservatively if the PIP joint is
horse through use of transfixation casts or external eminence fractures can be repaired by internal
skeletal devices has been described with/without stable. Biaxial fractures with instability of the PIP
internal fixation (if fragments allow) but infection, joint may require pastern arthrodesis (Fig. 1.224).
loss of vascular supply, collapse of the bone and Comminuted P2 fractures can be managed by trans-
catastrophic failure of the transfixation cast/fixator fixation cast and/or pastern arthrodesis, depending
are important problems that may be encountered. on the degree of comminution, or euthanasia.
Repair of comminuted P1 fractures with an intact
strut involves internal fixation, often through open Prognosis
reduction. The prognosis for short, incomplete fractures is
Horses with osteochondral fragmentation of the favourable but presence of osteoarthritis (OA) within
pastern joint can be treated conservatively or sur- the fetlock joint will reduce the final outcome. Horses
gically depending on the horse’s use and degree of treated surgically have a good prognosis for return
lameness. Palmar/plantar fragments can be ame- to soundness, whereas those treated conservatively
nable to surgical removal arthroscopically, although may remain lame and fracture propagation has been
described in horses not treated by internal fixation.
Success rates of up to 61–88% of horses returning
1.224
to racing following repair of incomplete sagittal P1
fractures are reported. Survival for comminuted
P1 fractures is guarded and those surviving often
remain lame. Fracture healing and arthrodesis of the
pastern following management of P2 fractures with
joint instability is associated with a fair outcome.

PASTERN SUBLUXATION

Definition/overview
Subluxation of the PIP joint.

Aetiology/pathophysiology
Commonly due to acute trauma, although it has
been reported in the hindlimb of juvenile horses,
without evidence of trauma. Subluxation in a dorsal
plane is usually due to severe disruption of the sus-
pensory apparatus, whereas palmar/plantar sublux-
ation is due to disruption to the distal sesamoidean
ligaments and/or insertion of the superficial digital
flexor tendon (SDFT). Avulsion of the collateral
ligaments can result in medial or lateral instability.
Fracture/subluxations are often present, particularly
in relation to collateral ligament avulsion.
Fig. 1.224 Dorsopalmar radiograph of two narrow
dynamic compression plates used for a proximal Clinical presentation
interphalangeal joint arthrodesis following a biaxial Most cases are acutely lame and associated with
P2 fracture. (Photo courtesy Graham Munroe) severe soft-tissue swelling and incongruity of the