Page 505 - Adams and Stashak's Lameness in Horses, 7th Edition

Lameness of the Distal Limb 471

A range from 50% to 70% return to soundness has
Type V been reported for horses with type II wing fractures
This fracture may be articular or nonarticular but
VetBooks.ir regardless is best treated with confinement and methods treated conservatively 44,49,56 However, a much better
success rate has been reported in Standardbred race-
to prevent hoof expansion (shoe or foot cast; see above
horses with 81% returning to training and 63% rac-
for details). Confinement alone is usually not recom-
43
mended for these fractures unless the fracture only ing. However, 89% that returned to training without a
bar shoe refractured at the same site, and 60% of horses
involves the apex of P3.
43
returning to training with a bar shoe raced successfully.
This is in contrast to nonracehorses, of which 69%
Type VI returned to their previous level of use and did not wear
a bar shoe when they returned to training. 44
Treatment of solar margin fractures depends on The prognosis for small extensor process fractures
whether the condition is primary or secondary to a treated by arthroscopic removal is generally considered to
chronic foot disorder (e.g. laminitis, osteitis, or infec- be very good to excellent. However, a recent study reported
tion). However, primary causes of solar margin fractures that only 46% of horses undergoing arthroscopic debride-
are usually treated with corrective shoeing (wide‐web ment of extensor process fragmentation remained sound
shoes, shoes and full pads, or shoes with rim pads) and after 4 years. Removal of chronic large extensor process
11
stall or paddock rest for several months. Strict immo- fragments also results in a good prognosis; 8 of 14 cases
29
bilization with bar shoes and quarter clips is not neces- returned to their intended use in one report and 14 or 17
15
sary. Prolonged rest appears to be required for the best in another. The prognosis for large extensor process frac-
9
fracture healing, but this often depends on the size of the tures treated by internal fixation also appears reasonably
fracture. If the cause is secondary, then treatment is good in the small number of cases reported. 36,46
directed at the underlying cause initially, followed by The type of P3 fracture with the most variable prog-
management of the solar margin fracture. 29 nosis is type III fractures. It remains unknown if affected
horses have an improved prognosis with lag screw fixa-
Type VII tion compared with confinement and corrective shoe-
ing. Variable success of surgical treatment has been
3
Affected foals with this fracture are usually treated reported. 3,24 In one study all fractures healed, but only 2
satisfactorily with confinement alone for 6–8 weeks. of 4 horses returned to athletic activity and surgery did
Exercise should be restricted until radiographic evidence not reduce the convalescence time required. An older
of bony union is evident, which is usually observed at study using internal fixation reported that 11 of 11
about 8 weeks after the diagnosis. 22,62 Application of horses older than 3 years of age became sound, and the
restrictive external coaptation (e.g. bar shoe or acrylic) most recent study that utilized CT guidance reported
to the hoof is not recommended because of the severe that 4 of 5 horses with sagittal/parasagittal fractures
heel contraction that can occur and the potential for the became sound. In contrast, conservative management
24
hoof to slough. of horses with type III fractures was reported to have a
OA of the DIP joint is a common sequela to articular 74% success rate for horses returning to their intended
P3 fractures. All racehorses with articular wing fractures use. Regardless of the treatment used, horses with type
49
that had follow‐up radiographs had evidence of OA on III fractures have a worse prognosis to return to perfor-
the radiographs. However, this did not preclude horses mance than the other types of P3 fractures, and refrac-
47
from racing, and the authors warned to not overinter- ture of the bone is more likely to occur. 46
pret radiographic abnormalities within the DIP joint.
Nonetheless, secondary abnormalities within the DIP joint
subsequent to articular fractures may limit future athletic SUBCHONDRAL CYSTIC LESIONS OF THE DISTAL
endeavors. Secondary OA of the DIP joint appears to be
5
more likely to develop with type III fractures than type II PHALANX (P3)
P3 fractures. If lameness persists, a neurectomy of the PD SCLs of the distal phalanx are uncommon and can
nerves may permit horses to resume athletic activity. In affect a wide variety of horse breeds of all ages. 4,60
racehorses with primarily type II fractures, 18% had a PD Affected horses are usually intermittently lame, and the
neurectomy performed, which completely resolved the forelimbs are more frequently affected than the
residual lameness and permitted them to race. 47 hindlimbs. Verschooten reported on 15 cases of SCLs
involving the distal phalanx, 14 of which were located
in the forelimb. In another study 27 of 28 cases
60
Prognosis involved the forelimbs. Most SCLs communicate with
27
In general, horses with hindlimb P3 fractures have a the joint surface, 28,59 although communication with the
better prognosis than those in the forelimb, and the prog- adjacent joint space can be variable. 60
nosis for nonarticular P3 fractures (types I, V, VI, and
VII) is usually very good for all ages of horses if sufficient Etiology
rest is given. 5,55 One recent study of 223 horses reported
a 91% return to expected level of activity for horses with Regardless of their location, the cause of most SCLs
type I P3 fractures and 80% for horses with type VI frac- in the horse is considered to be either trauma or devel-
49
tures. Foals with type VII P3 fractures usually have an opmental. 4,48 Damage to the subchondral bone in the
excellent prognosis for return to performance, and frac- stifle has been shown to cause SCLs of the medial femo-
ture healing is expected in about 8 weeks. 32,60 ral condyle, and SCLs can occur at sites of previous IA