Page 508 - Adams and Stashak's Lameness in Horses, 7th Edition

474 Chapter 4

that negative findings do not rule out the presence of a medial cartilage. The ossification can begin at the base
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19
lesion. Although concurrent osseous damage at the of the cartilage or originate as a separate area in the center
VetBooks.ir in approximately 50% of these horses, scintigraphy is had no ossification, 86% had ossification beginning at
of the cartilage.
In Brazilian jumpers, 7% of the horses
origin and insertion sites of the ligaments can be present
8,40
the base, and 7% had a separate center of ossification.
usually not recommended as an additional diagnostic
40
tool because MRI can usually provide more specific In either case, the palmar/plantar aspect of the cartilage is
information about the injury. likely to be spared from the ossification process. 51
In a radiographic study of 462 Finnhorses, 80% had
evidence of sidebones, and large sidebones or separate
Treatment centers of ossification were significantly more common in
53
The most important aspects of treating any soft tissue females than males. Ossification of the cartilages in the
40
injury of the foot are rest, rehabilitation, and corrective forefeet was present in 93% of Brazilian jumpers. Ten
foot care. 26,54 Foot imbalances that may have contrib- percent of Warmblood horses and 80% of draft horses
uted to their occurrence such as low heels, long toes, had ossification of the cartilages of the distal phalanx,
mediolateral imbalance, reverse angle of the distal pha- and the ossification was more extensive in draft horses
61
lanx, etc. should be corrected if possible. For example, than in Warmblood horses. The lateral and medial car-
one study that correlated radiographic findings with tilages were ossified equally in draft horses, but the lateral
MRI abnormalities found that a reduced palmar angle cartilages were more commonly involved in Warmbloods.
of the foot was correlated with alterations in the CLs of In this same study it was concluded that ossification of
the DIP joint. Horses should be shod to decrease tension the cartilage had no clinical significance. 61
on the side of the injury by increasing the width to the
branch of the shoe on the affected side and beveling the Etiology
shoe on the opposite (unaffected side). Rest and reha-
53
bilitation and corrective shoeing are usually performed The specific cause(s) of sidebones is(are) not clear. It
over a minimum of 6–8 months. Additional treatments has been suggested that the tendency to develop sidebones
for desmopathy of the CL of the DIP joint include extra- is partly hereditary in certain horse breeds in Australia,
corporeal shockwave therapy, application of a half‐limb Finland, and Sweden. 53,61 Hoof concussion causing
or foot cast, and medication of the DIP joint. However, trauma to the cartilage, poor conformation (particularly
26
one large study found no benefit of using extracorporeal base narrow), and poor trimming and shoeing have also
shockwave therapy or radial pressure wave therapy on been proposed as inciting causes. One study document-
outcome. Ultrasound‐guided intralesional therapy ing the incidence of sidebones in Finnhorses found that
13
with stem cells, platelet‐rich plasma, and other biologi- very few horses were base narrow and most horses were
53
cal products may also be used, especially if the injury is base wide and toed out. Another study concluded that
accessible above the hoof wall (see Chapter 8 for more ossification of the cartilages was neither the cause nor
detailed information on these treatment modalities). the result of conformational adaptations of the front
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feet. It has also been suggested that prolonged exercise
and/or racing may have some preventative influence on
Prognosis ossification of the collateral cartilages. The amount of
The reported prognosis for horses with desmopathy weight placed on the foot may also be contributory
of the CL of the DIP joint is variable. One study reported because primarily larger‐breed horses develop sidebone.
that only 29% of horses treated with rest and rehabilita-
tion returned to athletic function, while another study Clinical Signs
19
indicated that 60% of treated horses (12 of 20) returned
to their previous level of exercise. Another study that Lameness resulting from sidebones is considered rare,
26
followed horses for 2 years after presentation deter- and the clinical significance of radiographic apparent
5
mined that only 27% of horses with CL injury alone ossification is questioned. One study found no correla-
and 34% of horses with CL‐related osseous injury tion between the extent of ossification of the collateral
61
returned to their previous performance. Horses with cartilages and the onset of lameness. Furthermore,
13
multiple soft tissue and osseous injuries within the hoof despite the development of large sidebones in many
capsule did substantially worse. In general, these horses Finnhorses, most horses performed satisfactorily with-
53
have a poor prognosis for future performance. out lameness. However, large sidebones have been seen
in horses associated with type I or II distal phalanx frac-
tures by the author and were thought to contribute to
OSSIFICATION OF THE COLLATERAL CARTILAGES the fracture and chronic lameness (Figures 4.35 and
OF THE DISTAL PHALANX (SIDEBONE) 4.43). A recent MRI study of horses with ossified ungual
cartilages and a P3 facture found that all fractures
Ossification of the collateral cartilages of the distal occurred at the base of the ossified cartilage extending
phalanx is relatively common in certain breeds of horses, into the distal phalanx suggesting a biomechanical cause
including most larger breeds such as Warmblood horses, or focal stress point from cycling. However, these
draft horses, Finnhorses, and Brazilian jumpers. 40,51–53,61 fractures were nonarticular and nondisplaced, but the
The forefeet appear to be more commonly involved than ligaments and soft tissues adjacent to the ossified ungu-
the hindfeet, and the clinical significance of the condition lar cartilages were abnormal. 57
remains questionable. Female horses appear to be more In a scintigraphic study, a radiographically identified
61
susceptible to development of this condition, and the lat- separate center of ossification could be detected with
eral cartilage often shows more ossification than the scintigraphy in 12 of 17 feet. 21,41,42 The authors suggested