Page 57 - Manual of Equine Field Surgery

Transphysea Bridging 53
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potentially severe performance-limiting conse-

quences of a carpal varus deformity that may

result from delayed removal of transphyseal

bridge implants. Timely removal of implants is

essential to reduce the frequency of this compli-

cation.

ALTERNATIVE PROCEDURES

An alternative to the open technique as described

involves performing the surgery through stab

incisions made over the location of each screw

site.2 The soft tissues between the screw holes are

bluntly undermined with mosquito hemostatic

forceps forming a tunnel for passage of the

figure of eight wires. Postoperative care is as

described for tl1e open technique for transphyseal

bridging.

An alternative to screws and wires for Figure 7-5 Dorsopalmar radiograph of the carpus

transphyseal bridging is the use of orthopedic with a single 4.5-min cortical bone screw placed across

staples, initially described in 1963.3 Staples have the distal radial physis as a11 alternative for transphyseal

the advantage of being easier and quicker to bridging.

place and have a low complication rate.4 Two

sizes of staples are commercially available: 22 x screw can be placed distal to proximal or proxi-

22 mm (Zimaloy Epiphyseal Staple; Zimmer, Inc., mal to distal as shown in Figure 7-5.

Warsaw, Ind.) and 29 x 22 mm (Blount E.S.;

Stryker, Kalamazoo, Mich.). Disadvantages of sta-

ples include the lack of compression across the COMMENTS

growth plate in the early postoperative period and

the limited flexibility in placement caused by the The primary advantage of transphyseal bridging

fixed leg length of the staple. compared with periosteal transection and eleva-

Another alternative is the recently described tion is the more consistent response achieved even

technique for the placement of a single transphy- in severely deformed or older patients. Unless the

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seal screw for transphyseal bridging. The de- physis is damaged on the side opposite the side

scribed technique involves the placement of a bridged or the physis is too mature to respond,

single fully threaded screw at an oblique angle i11 correction will occur. The disadvantages of the

lag fashion from the medial malleolus, across the procedure include increased time and cost of

physis and into the metaphysis of the tibia. The the procedure, the increased risk of infection, the

approach to the medial malleolus is via a stab inci- increased likelihood of a less-than-satisfactory

sion and is associated with minimal soft tissue cosmetic appearance, the requirement for more

dissection. Advantages cited for this technique special equipment, the possibility of overcorrec-

include reduced need for soft tissue dissection, tion, and the need for a second surgery to remove

improved cosmetic result, and reduced risk of the implants to avoid overcorrection.

infection. Although the authors indicate they had · The differential diagnoses for angular limb

used this procedure in the treatment of carpal deformities in foals include intercarpal or inter-

valgus, the current report was limited to treat- tarsal ligament laxity, crushed carpal or tarsal

ment of tarsal valgus in 4- to 12-month-old bones, distal radial or tibial physeal dysplasia, and

horses. 111 this report of 11 cases, the tarsal valgus physeal trauma resulting in premature closure of

resolved and the cosmetic result was considered the physis. Ii1 addition, angular limb deformities

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excellent. We have used this method for correc- may also be associated with the metaphysis or dia-

.tion of carpal valgus in foals. In the carpus, the physis of long bones, typically the third metacarpal

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