Page 636 - Adams and Stashak's Lameness in Horses, 7th Edition

602 Chapter 5

The efficacy of periosteal stripping has come under
debate in recent years. 100,110 Although some clinicians
VetBooks.ir lack of efficacy. 100,110 The studies show that the limb will
feel that it still has merit, two studies demonstrated its
typically correct on its own with proper foot trimming.
Slone found that there was no difference between horses
that underwent the procedure and those that had stall
rest and appropriate hoof manipulation. 110
Transphyseal bridging, which retards growth on the
convex side of the limb, is more predictably effective
than periosteal transection for correcting ALD. The
40
procedures include:
1. Placing two screws and a figure‐8 wire on the convex
side, in which a screw is placed proximal and distal
to the physis and wire interlaced between the screws
to stop the growth on that side
2. Placing a staple or plate across the physis 13
3. Placing a transphyseal screw at an angle across the
physis on the convex side
Significant growth does not slow in the distal radial
physis until approximately 16 months of age; therefore,
transphyseal bridges can be used out to 16–20 months
of age in the carpus. These bridges are most effective
41
between 0 and 8 months of age, when the most rapid
growth occurs. Bridges also can be used in severe cases
younger than 6 months of age or in older cases that are
nonresponsive. It has been suggested that the screw and
wire technique be used in foals less than 6 months of
age and a transphyseal screw in those older than 6
128
months of age because of concern of bone bridging across
the physis and overcorrection of the deformity after
removal of the transphyseal screw. However, it appears
that approaches are changing. The author currently will
use a transphyseal screw in most cases of varus and val-
128
gus deformity. Witte et al. have not seen a problem
Figure 5.5. Front view of sleeve casts applied to both forelimbs. with bone bridging, and Baker et al. saw no complica-
Source: Courtesy of Dr. Ted Stashak. tions when used to correct cases of carpal varus. In fact
they saw no deleterious effects on sales prices or racing
6
performances in those foals. Baker et al. showed that in
However, close observation is needed, especially in the foals less than 2 months of age that had bilateral carpal
first few days. It is important to observe the foal before it valgus (some deemed severe up to 17°), unilateral peri-
goes out and assess the degree of ALD. The typical rec- osteal transection had no comparable effects to the
ommendation is to turn the foal out for a couple of hours unoperated limb. This lends considerable support to the
initially and reassess the degree of deformity when the fact that at this age considerable improvement in angu-
foal comes back in. It is not uncommon to see the ALD lar deviation can occur with conservative treatment. 7
worsen and/or the foal develop a mild flexural deformity The concern with the transphyseal screw technique is
and/or shaking in the carpal joints when it comes in from that although it is simple and quick, the effects of the
turnout. If this occurs, the foal’s amount of turnout screw on normal physeal physiology are not completely
should be decreased until these signs cease. Foals usually understood. The screw and wire technique can be used
respond quite rapidly, reaching significant or even full through two stab incisions and then the tissues in between
turnout within 7–14 days. Increased turnout may help undermined to place the wire to minimize scarring and
strengthen and broaden the chest in narrow‐chested foals potential soft tissue complications. It is not necessary to
in which carpal ALD and external limb rotation are con- countersink the screws because that makes removal more
cerns, resulting in a more normal limb conformation. difficult. In addition, some surgeons feel that the screws
Surgical options are used when the foal either fails to can be offset in the cranial to caudal direction to address
respond to conservative therapy or the angulation is rotational abnormalities that may originate at the carpus.
severe enough that it is unlikely to correct on its own. In some cases, a transphyseal screw can be placed across
Periosteal transection has been used for decades to help the distal lateral radial physis in the standing yearling.
88
correct ALD. 4,48 The rationale is that endochondral ossi- In nearly all cases, the screw must be removed, and this
fication is stimulated on the side in which the perios- can generally be done standing or under a quick general
teum is transected and elevated. 4,25 In the carpus this is anesthesia in more difficult foals.
typically done on the concave side of the distal radial In some cases a dorsomedial toe extension is pre-
metaphysis 3 cm proximal the physis. ferred for foals with valgus deformity, to help further