Page 717 - Adams and Stashak's Lameness in Horses, 7th Edition

Lameness of the Proximal Limb 683

form of specific trauma. These fractures are more complicated because the curved nature of the fracture
likely to involve both the CT and T3 bones and are plane makes it difficult to image. In addition, because
VetBooks.ir severe lameness that diminishes over several weeks. injury, serial radiographic examinations may be neces-
the fracture line may be difficult to appreciate soon after
more likely to be comminuted (Figure 5.85).
Horse with slab fractures can initially present with
sary to identify the presence of a slab fracture. When
There can be little indication of a slab fracture. Simple conventional imaging techniques (radiography and
slab fractures of the T3 bone often have minimal swell- ultrasound) cannot detect a problem, nuclear scintigra-
ing or synovial effusion to indicate the location of the phy can be utilized to demonstrate active bone remode-
injury. Synovial effusion may occur with CT fractures ling associated with the fracture. CT and MRI can
that enter the PIT joint. Racehorses that have a moder- provide cross‐sectional imaging that is ideally suited for
ately positive response to proximal limb flexion test an accurate diagnosis but also a prerequisite for surgical
when compared with the opposite limb should be evalu- repair. Multiple fracture lines that were undetectable with
ated for tarsal slab fractures. When the CT bone is standard radiographic exam can often be identified mak-
fractured, intra‐articular anesthesia of the TC joint may ing the surgical treatment (screw placement) more accu-
partially alleviate lameness, but it can take 30–45 min- rate even though the prognosis becomes less favorable.
utes for maximal effect. Diagnosis of CT and T3 bone Developmental abnormalities such as wedging of the
fractures is confirmed with standard radiographic T3 may be a predisposing factor to formation of slab
views but can require multiple oblique projections. fractures of the DT bones. These tend to occur in dysma-
Radiographic confirmation of these fractures may prove ture foals with hypoplastic tarsal bones that have col-
difficult because the radiographic beam angle must be lapsed on the dorsal or dorsolateral portion of the third
tangential to the fracture plane to identify them. This tarsal bone creating a wedge shape. Third tarsal bone
requires that radiographic exam includes a series of dif- slab fractures occurred more commonly in the left
ferent oblique angles to more accurately demonstrate hindlimb of racehorses, while TC bone fractures were
the fracture. The radiographic diagnosis can be further more often complex and comminuted.

A

B
Figure 5.85. Slab fractures that occur in nonperformance comminuted CT bone fracture can be seen in the top CT image (A),
breeds are often due to some form of external trauma and are more and a T3 bone fracture is visible in the bottom CT image (B).
likely to involve multiple tarsal bones and be comminuted. A