Page 566 - Adams and Stashak's Lameness in Horses, 7th Edition

532 Chapter 4

VetBooks.ir

Figure 4.112. Dorsopalmar and lateral radiographs post‐op and 3 months later at the time of hospital discharge of a severely
comminuted P1 fracture treated with limited internal fixation and a transfixation pin cast.

and iatrogenic metacarpal/metatarsal fractures through different. In another study with Standardbred race-
27
the pin tracts are complications of using transfixation horses, 89% of the horses returned to racing, but at sig-
pin casts. 29,35 The addition of internal fixation is some- nificantly decreased performance levels. In another
69
times also used with external fixation to improve joint study in young Thoroughbred racehorses, 70% of the
alignment and reduce longitudinal fracture collapse. horses treated conservatively with short, incomplete
Casting alone can be used to treat some horses with sagittal fractures raced, and 65% of the horses with
comminuted P1 fractures, but it is less than optimal. long, incomplete sagittal fractures treated conservatively
Case selection is important and the fracture should be raced. Horses with dorsal frontal fractures treated by
17
minimally comminuted and relatively stable to prevent lag screw fixation also appear to have favorable progno-
39
axial collapse of the fracture. Complications associ- sis to return to performance. 11,39
ated with using a cast alone to treat severely commi-
nuted and unstable P1 fractures include (1) axial collapse Comminuted Fractures
of the fracture, potentially leading to an open fracture,
(2) supporting limb laminitis, (3) excessive callus forma- Horses with open or closed severely comminuted frac-
tion and OA of the MCP/MTP and PIP joints, (4) short- tures that do not permit reconstruction of the fragments
ening of the pastern region, and (5) partial ankylosis of remain difficult to treat and have only a fair prognosis for
the MCP/MTP joint. 17,32 Because of these numerous survival, regardless of the treatment approach used.
complications, external coaptation alone is not recom- Moderately comminuted P1 fractures (those with an intact
mended for treatment of horses with severely commi- bony strut) can usually be repaired with internal fixation,
32
nuted P1 fractures. In addition, casting or external and a 92% successful outcome has been reported.
skeletal fixation is not recommended for horses with Reasons for euthanasia of horses with comminuted P1
moderately comminuted P1 fractures because of the fractures include economic constraints, fracture collapse,
very good success with internal fixation of these iatrogenic metacarpal/metatarsal fractures, contralateral
fractures. 32 limb laminitis, and infection of the fracture site. 29,32,35

Prognosis DESMITIS OF THE DISTAL SESAMOIDEAN
Noncomminuted Fractures LIGAMENTS (DSLS)
The prognosis for performance with noncomminuted There are three DSLs: the straight (superficial), paired
fractures of P1 often depends on the configuration of oblique (middle), and paired cruciate (deep)
the fracture, duration of the fracture until treatment, (Figure 1.11). All of the ligaments originate from the
method of treatment, and breed and intended use of the base of the proximal sesamoid bones and intersesamoid-
horse. 11,17,27,69 In one study in racehorses, a significantly ean ligament. The straight ligament attaches distally to
lower percentage of horses returned to racing following the proximopalmar/plantar aspect of P2, and the paired
repair of complete sagittal fractures that extended into oblique ligaments attach to a triangular region on the
the PIP joint (46%) than following repair of short middle and distal third of P1. The paired cruciate liga-
incomplete sagittal fractures (71%), long incomplete ments attach distally to the contralateral eminence of
sagittal (66%), or complete sagittal fractures that the proximal extremity of P1. There are also paired
extended to the lateral cortex (71%). The time from short ligaments that attach at the proximal articular
fracture to repair did not affect the outcome. Additionally margins of the MCP/MTP joint but are not considered
the median number of races and the median fastest race to be part of the DSL complex. See Chapter 1 for further
times before and after surgery were not significantly information regarding the anatomy of the DSLs.