Page 564 - Adams and Stashak's Lameness in Horses, 7th Edition

530 Chapter 4

In general, most noncomminuted P1 fractures involve of the fracture. The most proximal screw should be
an articular surface (MCP/MTP and/or PIP joint) and placed within 5 mm of the most distal point of the sagit-
VetBooks.ir placed through stab incisions. Horses with displaced ing is recommended to ensure that the MCP/MTP joint
tal groove in P1. Radiographic or fluoroscopic monitor-
are best treated with internal fixation using lag screws
is not entered and to document fracture compression. If
fractures that are not treated with internal fixation have
a reduced chance of returning to performance. a cast is used postoperatively, it is generally removed
Short, incomplete sagittal fractures can be treated after 10–14 days. Others prefer bandage support only
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conservatively with pressure bandaging and stall rest, for recovery from anesthesia.
but most are treated with lag screw fixation. 27,32,33 Complete sagittal fractures that extend distally from
Fracture propagation is a risk of treating short incom- the MCP/MTP joint to involve the PIP joint or that exit
plete sagittal fractures conservatively, and this occurred the lateral cortex are best treated by internal fixation
17
in 3 of 85 racehorses in one study. These fractures heal and coaptation. These fractures are often displaced and
with a periosteal callus over the dorsal aspect of the can generally be better reduced with open approaches to
fracture site, which does not appear to limit function. If P1 followed by lag screw stabilization. Plate fixation
the fracture has not healed after 3 months, lag screw may also be used, depending on the fracture configura-
fixation is recommended. However, a recent study found tion. However, lag screw fixation through stab incisions
an improved prognosis in nonracehorses with short, similar to incomplete sagittal fractures may be sufficient,
incomplete sagittal fractures that were treated with lag depending on the degree of displacement. A distal limb
screws. Horses treated conservatively remained lame, cast is usually recommended after surgery for 2–4 weeks,
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only 1 of 4 horses had radiographic evidence of fracture depending on the security of the fixation.
healing, and 2 of 4 horses had catastrophic propagation Bandaging and/or external coaptation has been used
of the fracture. In addition, another study indicated that alone in cases in which breeding soundness is the objec-
all incomplete sagittal fractures greater than 15 mm tive or if there are economic constraints. In general,
should be treated surgically. 69 horses that are treated conservatively require about
Horses with long (greater than 30 mm) sagittal 4 months to become free of pain and lameness. They
incomplete fractures that are to be used for racing often develop considerable exostosis at the fracture site
should be treated with lag screw fixation placed through and secondary OA of the MCP/MTP joint, which may
stab incisions followed by external coaptation cause lameness when they resume work. 17,39
(Figures 4.104B and 4.110). Two to three screws placed Dorsal frontal incomplete or complete nondisplaced
20 mm apart are generally used depending on the length P1 fractures can be treated by rest and bandaging or by
internal fixation using lag screws, depending on the
fracture size. Needles placed into the MCP/MTP joint
during the repair may help determine the proper place-
ment of the screws. Arthroscopic examination of the fet-
lock joint should be considered to visualize the dorsal
articular margin and debride damaged cartilage if
needed. A cast or bandage may be used postoperatively.
Complete dorsal fractures that extend into the PIP joint
are best treated by lag screw fixation using an open
approach or through stab incisions and external coapta-
tion. Needles placed in the MCP/MTP and PIP joint
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help guide the placement of 3–4 screws. A half‐limb cast
is recommended after surgery and is generally removed
in 3 weeks. Fracture healing and return to training can
be expected earlier following surgical treatment than
with nonsurgical treatment of these fractures.
Distal articular fractures occur almost exclusively in
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the hindlimbs and appear to be more common in foals.
The acute fracture is generally best treated by lag screw
fixation and external coaptation. If the fracture is
chronic, secondary OA of the PIP joint is likely and
arthrodesis of the PIP joint is recommended.
Physeal fractures are usually Salter–Harris type II
fractures and are most common in weanlings. 11,39
Minimally displaced fractures are generally best treated
conservatively with stall confinement and bandage sup-
port. In one report (four cases), all of these fractures
healed with a moderate degree of malunion, but P1
remodeled so that a normal hoof‐pastern axis was main-
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tained. If the fracture causes limb deformity and can-
not be reduced, internal fixation may be required. If the
Figure 4.110. Dorsopalmar radiograph of the midsagittal PIP joint becomes subluxated as a result of the injury,
incomplete P1 fracture illustrated in Figure 4.104B that was treated arthrodesis of the PIP joint is recommended to realign
with two 4.5‐mm lag screws placed through stab incisions. the phalanges.