Page 577 - Adams and Stashak's Lameness in Horses, 7th Edition

Lameness of the Distal Limb 543

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A B
Figure 4.124. Arthroscopic images of a small dorsoproximal P1 fragment before (A; arrow) and after (B) fragment removal.

condyle. 28,49 It is recognized that some small nondis- at arthroscopy decreased the prognosis in racing
placed fractures can be treated successfully with adequate Thoroughbreds, but success was still good (greater than
rest for 120 days. If training continues, these fragments 70% return to racing). 24,49,56,108
often displace and cause adjacent articular cartilage ero- Small acute, nondisplaced fetlock chip fractures usu-
sion. Two to four months of rest and controlled exercise ally have a good prognosis with conservative treatment.
is recommended before the horse is returned to a regular Arthroscopic surgical removal may still be elected in
exercise/training program. This somewhat depends on these cases because the convalescence is shorter after
the degree of joint damage and cartilage debridement. In surgical removal (often under 30 days) than for the bone
some horses, small frontal fractures of the dorsal margin to heal (90–120 days) and the risk of fracture displace-
of proximal P1 are identified. These fractures can heal ment or refracture is eliminated. Factors that lower the
with conservative management but if lameness persists, prognosis include extreme large size of the fragment,
some have advocated compression of the fracture with chronicity, degree of synovitis/capsulitis, and amount of
small screws (2.7 or 3.5 mm). 106 OA present. Standardbred racehorses often have chronic
Fractures of the palmar/plantar eminence can be joint changes associated with dorsal P1 fractures. In
treated conservatively, but due to the soft tissue attach- general, racehorses that develop dorsal P1 fractures
ments, there typically will be a large degree of osseous have reduced lifetime earnings compared with race-
remodeling around the fracture due to movement. horses that do not develop these fractures. 59
Osteoarthritis (OA) of the fetlock joint typically results The prognosis for proximal palmar/plantar fractures
in varying degrees. If the fragment is large enough, inter- that require compression screw fixation depends on the
nal fixation with lag screw(s) may allow for a faster degree of initial trauma at the time of fracture. Often
return to function and may lessen the development of this is not fully appreciated until the radiographs are
OA. Removal of smaller fragments is also an option. taken 3–4 months after surgery. The prognosis after
Typically, these horses are in a rest and rehabilitation removal of smaller proximal palmar fractures is consid-
program at least 4–6 months to allow time for the bone ered to be very good, although the benefit of removal
and adjacent soft tissues to heal. The benefit of remov- has been questioned in Standardbred racehorses. 19,20
ing palmar/plantar fragments to improve performance
has been questioned based on a study that indicated
there was no difference in racing speed, career earnings, FRACTURES OF THE PROXIMAL
or lifetime starts between Standardbred racehorses with SESAMOID BONES
the fracture and those without. 19
Fractures of the proximal sesamoid bones are com-
Prognosis mon injuries in racing Thoroughbreds, Standardbreds,
and Quarter horses. 6,15,18,54,67,78,79,83,84,86,92 These fractures
The prognosis is usually good to excellent for treat- take various forms including apical, abaxial (articular
ment of proximal dorsal chip fractures, but it is some- and nonarticular), midbody, basilar (articular and non-
what dependent on the size and number of chip fractures, articular), sagittal, and comminuted. Combinations of
their duration, whether or not corticosteroids have been fracture types such as apical/abaxial fractures may also
injected, amount of concomitant articular cartilage occur. The forelimbs are most frequently affected in the
damage, and degree of OA. Several reports indicate that Thoroughbred (right forelimb) and Quarter horse,
the prognosis for return to athletic performance, includ- whereas the hindlimbs are more frequently affected in
ing racing performance, is good to excellent (approxi- the Standardbred (left hindlimb). Most of these frac-
mately 80%) with arthroscopic surgery to remove the tures distract as a result of the pull of the SL proximally
fragment. 19,20 The presence of other fetlock lesions noted and the distal sesamoidean ligaments (DSLs) distally.