Page 52 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

Musculoskeletal system: 1.1 A pproach to the lame horse 27

VetBooks.ir careful preparation and positioning of the limb, clean- (Fig. 1.51). Casts should ideally be changed at
7–10 days post surgery to account for a decrease in soft-
ing of the foot and preplacement of suitable wound
dressings, and a cast lining with stockinette, appro-
and every 7–10 days in foals depending on the case.
priate padding with orthopaedic felt and general limb tissue swelling, and then at least every 4 weeks in adults
padding such as Cast Support Foam prior to place-
ment of the cast material itself (Fig. 1.50). Surgical
Frequent cast changes due to loosening of the External fixation
cast and cast-related soft-tissue problems such as Transfixation casting The combination of two or
pressure sores is expensive and, if carried out under three 4–6 mm positive-profile pins with a 30° diver-
general anaesthesia, puts the horse under unneces- gence in a frontal plane through the third metacar-
sary anaesthetic and recovery risk. Casts are more pus/metatarsus and a fibreglass cast provides a strong
commonly used to protect internal fixations during protection for comminuted fractures distal to the pins
anaesthetic recovery and until good fracture heal- (i.e. of P1, P2 and distal third metacarpus/metatar-
ing is well under way (e.g. a lateral condylar third sus). The load of weight bearing is transferred away
metacarpal fracture repaired by lag screw fixation from the fracture site via the pins and cast and there is
is protected with a half-limb cast). Long-term cast minimal distraction of fragments. These casts can be
use can lead to DJD due to immobilisation of joints, maintained for up to 6–8 weeks.
laxity of the soft-tissue structures around the joints
and disuse osteoporosis if the treated limb remains External fixator Several small animal versions of
non-weight bearing for an excessive period of time. these are infrequently used for severely comminuted
Daily cast checks are necessary to prevent sores fractures of P1, P2 and distal third metacarpus/
developing (especially dorsoproximally at the can- metatarsus. They have been used in foals with fractures,
non, fetlock and coronary band for a half-limb cast) but many surgeons use positive-profile pins stabilised

1.49 1.50

Figs. 1.49, 1.50 Hindlimb
half-limb cast used for the post-
anaesthetic recovery of a horse
that had undertaken a surgical
repair of a hindlimb first phalanx
fracture (1.49). Note the layers of
the cast, including the yellow cast
foam, after it has been split prior to
removal (1.50).