Page 118 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

Musculoskeletal system: 1.3 The foot 93

VetBooks.ir plantar process fractures, originating and ending at 1.164
the solar margin. Non-displaced incomplete or com-
plete stress fractures of a palmar process at the base
of the ungual process have been described in associa-
tion with the presence of sclerosis of the palmar pro-
cess and ossification of the adjacent ungual cartilage.
Distal phalanx fractures heal slowly and, in some
cases, only by fibrous union. In either instance some
horses will become sound, whereas others develop
persistent lameness due to OA of the DIP joint.

Clinical presentation
Horses with an acute distal phalanx fracture present
with a severe acute lameness. Horses with chronic
fractures may present with a chronic lameness of
moderate severity. Articular fractures tend to cause
more severe clinical signs.
Fig. 1.164 T1-weighted MR image of an incomplete
palmar process stress fracture (arrow).
Differential diagnosis
Abscesses; puncture wounds; navicular bone frac-
ture; acute strain or sprain; separate centre of ossifi- radiographically. Pain from non-articular palmar
cation of the extensor process. process fractures may be alleviated with a uniaxial
palmar digital nerve block, while elimination of pain
Diagnosis from most other types of distal phalanx fracture
In horses with acute fractures there is heat in the requires a bilateral abaxial sesamoid nerve block.
foot, increased digital pulses and pain on application Chronic fractures of the extensor process may
of hoof testers, and they must be distinguished from cause distortion of the coronary band and defor-
the other causes of acute lameness. Radiographs are mation of the dorsal hoof wall (i.e. a buttress foot).
often not taken initially, while other causes are inves- Chronic articular fractures that cause OA usually
tigated. Dorsopalmar, 45° dorsoproximal/ palma- demonstrate lameness that is exacerbated with distal
rodistal oblique, lateromedial and 60° dorsoproximal/ limb flexion and dorsal distension of the DIP joint.
palmarodistal oblique projections are routinely per- DIP joint analgesia will localise the problem and
formed and, depending on the configuration of the radiography will identify the presence of OA.
fracture, additional 30–45° medial or lateral oblique
views may be required. An acute non-displaced frac- Management
ture may be difficult to identify radiographically. Acute fractures of the body or wings of the distal
Repeating the radiographs after 7–10 days may help phalanx are usually treated by limiting movement
identify these fractures, after early osseous resorption of the hoof capsule to reinforce the natural splint-
of the fracture margins has occurred. Scintigraphy ing it provides to the distal phalanx. This is achieved
is effective in demonstrating the presence of occult optimally by placing a rim cast, which incorporates
fractures, determining the importance of chronic the heel bulbs, around the perimeter of the foot.
fractures that have healed by fibrous union and the Alternatively, a bar shoe with a continuous rim that
significance of solar margin fractures. Diagnosis of extends 1–1.5 cm proximally can be fitted and the
non-displaced palmar process stress fractures fre- space between the rim and hoof wall filled with a
quently requires MRI (Fig. 1.164). Regional anal- synthetic composite. Bar shoes with quarter clips
gesia is occasionally needed to confirm the presence are frequently used but are not as effective as these
of foot pain when fractures cannot be detected other measures. Shoeing with a rim or clips for this