Page 718 - Adams and Stashak's Lameness in Horses, 7th Edition

684 Chapter 5

Treatment of choice is lag screw fixation of the slab prognosis by providing accurate fracture assessment
fracture(s) of CT and T3 bones. Conservative treatment and is the best imaging tool to accurately direct screw
VetBooks.ir with some horses returning to athletic use. However, fractures can be repaired with two or three 4.5‐ or 5.5‐mm
placement. The medial fragment is usually smaller, and
(prolonged stall rest) has also been utilized successfully
101
treatment by screw fixation offers the best prognosis,
cortex screws placed in lag fashion from medial to lat-
because conservative management usually results in eral. Prognosis is thought to be favorable if accurate
increasing dorsal displacement of the fracture fragment anatomic reduction can be achieved. Comminuted
69
creating articular incongruity leading to OA. The goal fractures of the talus are often associated with severe
for articular fracture fixation is to promote primary soft tissue trauma that can lead to destabilization of the
bone healing and maintain and/or restore bone congru- TC joint. These cases are inoperable in most cases.
ity and diminish the chances for the development of OA.
The screw placement should be placed as close to per- Fractures of the Trochlear Ridges of the Talus
pendicular (90°) to the fracture line as possible and as
close to the middle of the fragment (usually in a dorso- Significant effusion of the TC joint exists with most
lateral to plantaromedial orientation). Some commi- fractures of the talus. As with most fractures of the tar-
nuted CT fractures are impossible to repair and are best sal area, flexion tests are often moderate to severely
treated conservatively. Horses are rested for 4–6 months positive. The clinical signs vary considerably and depend
after surgery. on the size and location of the fragment, the amount of
Prognosis is dependent on the detection of all of the displacement, and the presence of any comminution.
fracture lines, particularly with CT fractures. If pro- The position that the limb was in when the horse was
longed lameness persists in spite of apparently success- kicked (i.e. flexed or extended) dictates the location of
ful repair, removal of the screw may be necessary. Horses the fracture (point of contact). For example, the caudal
that undergo very strenuous activity will likely do better aspect of the proximal MTR can be traumatized when
if treated by lag screw stabilization. Residual lameness the limb is flexed (Figure 5.62B), and the distal aspect of
can persist after either surgical or conservative manage- the LTR is exposed when the limb is extended. Fractures
ment and eventually may require intra‐articular medica- to both trochlear ridges are more serious because of the
tion, chemical or surgical arthrodesis, or screw removal loss of TC joint stability created by the anatomic inter-
after fracture healing. digitation of the trochlear ridges with the cochlea of the
distal tibia. Fractures that involve both trochlear ridges
Sagittal Fractures of the Talus can develop during severe twisting movements of the
affected limb with the hock partially flexed, which
Stress fractures associated with high‐speed exercise transfers the tibial contact region to the distal areas of
tend to occur at similar locations and configurations the trochlear ridges of the talus. Fractures of the troch-
and usually without a known specific traumatic event. lear ridges are not typically difficult to differentiate from
Racing or competitive speed events can occasionally cre- OCD fragments particularly of the LTR. Standard radi-
ate exercise‐induced sagittal fractures of the talus. 31,69,95 ographic examination of the tarsus should help to con-
These fractures are rare and most commonly diagnosed firm the diagnosis but often needs to be supplemented
in the STB and TB racehorse but occasionally can be with a flexed lateromedial and flexed lateromedial
encountered in other breeds. The diagnosis is suspected obliques to highlight the different trochlear ridges.
when there is moderate to severe lameness in association Conservative therapy in most cases is unrewarding.
with distension of the TC joint. These fractures are often Surgical treatment is often indicated to alleviate the
incomplete and nondisplaced and may prove challenging lameness and persistent effusion. Intra‐articular frag-
to diagnosis with standard/conventional radiographic mentation of the trochlear ridge(s) warrants arthro-
techniques. Extra views including a dorsal 10°–20° lat- scopic removal. Large fragments consisting of the distal
eral to plantaromedial oblique and a flexed dorsoplan- one‐third to one‐half of the LTR may be candidates for
tar (skyline) view can be helpful. Nuclear scintigraphy anatomic reduction and lag screw compression of the
can be very helpful in confirming the presence of a stress fragment to the talus. This may require recessing the
reaction or fracture, usually by revealing an intense focal heads of 3.5‐mm cortical bone screws or small cannu-
IRU in the proximal aspect of the talus. Eleven race- lated screws. Diverging polydioxanone (PDS) resorbable
horses with a history of chronic, mild hindlimb lameness pins may also be useful in these fractures. The plantar
that became acutely lame during a race were diagnosed aspects of the TC joint should be examined to evaluate
with a sagittal fracture of the talus. 31,69 Sagittal fractures the proximal portion of the trochlear ridges for damage
of the talus found in other types of horses are thought to and to clean up floating debris. Fragmentation of the
be associated with trauma and may be more compli- plantar trochlear ridges can also occur and usually
cated than what is found in the racehorse. Stall rest until require removal. The arthroscopic portal is placed on
the horse becomes sound, and then 2 months of pad- the same side of the joint as the fragment(s) and arthro-
dock exercise will normally result in resolution of the scopic removal of the fragment(s) via the plantar pouch
problem and a favorable outcome. is performed on the ipsilateral side.
Horses with complete sagittal fractures can be treated
with lag screw compression of the talus using two 4.5‐ Fractures of the Tibial Malleoli
mm cortical bone screws. 31,69,95 Prognosis may be favora-
ble in horses with simple acute fractures, but the Traumatic injuries of the tarsus can lead to fragmen-
prognosis for horses with comminuted fractures is poor. tation of the CL attachment onto the malleolus (most
The use of CT is advantageous and can improve the often the LM of the short lateral collateral ligament