Page 719 - Adams and Stashak's Lameness in Horses, 7th Edition

Lameness of the Proximal Limb 685

[sLCL]). These fractures may exist intra‐ or extrasynovi- may displace into the plantar pouch necessitating a differ-
ally. Fragmentation that occurs intrasynovially may ent surgical approach.
VetBooks.ir indication for surgical removal. However, US examina- mended. Healing is compromised due to the displacement
Surgical removal of the fragment is frequently recom-
cause a persistent synovitis, and this may be a primary
tion of the affected CL is critical to assess its degree of
of the fragment inhibiting primary bone healing. In addi-
damage to prevent further injury that may occur on tion, the intrasynovial position of this fracture fragment
recovery from general anesthesia. perpetuates the shedding of debris into the joint, increasing
The origin of both medial and lateral CLs are located the chance for widespread cartilage injury and the develop-
both on the LM and MM of the tibia, respectively. ment of OA. Lateral malleolar fractures are typically
Fragmentation of the attachment of the sCL is most smaller, displaced, and comminuted but carry a reasonably
common although avulsion fractures of the long lateral good prognosis compared with MM fractures. Two recent
collateral ligament (lLCL) do occur. Fractures and/or reports document that LM fragments can be successfully
bony change associated with the CLs is best demon- removed with arthroscopic techniques. In those reports,
strated on the dorsoplantar radiographic projection. horses with fractures of the LM had a favorable prognosis
Multiple radiographic projections may be necessary to for return to full athletic performance following arthros-
assess the extent of bony change(s) associated with the copy and that arthroscopic fragment removal is the pre-
injury. Fragment removal should not compromise the ferred treatment method. Medial malleolar fractures are
stability of the TC joint provided that the long CLs often larger, are more difficult to remove, and may have
(MCL, LCL) are not affected. The LM appears to be lMCL involvement. Surgical removal of LM fragments car-
more frequently affected than its medial counterpart; ries a reasonably good prognosis for attaining soundness.
42 of 44 cases that have been reported in the literature Large fractures of the tibial malleoli are almost
have involved the LM. 75,108,148 This is probably due to always articular (Figure 5.87). Large fragments with sig-
the fact that the LM is considered to be the distal end nificant CL compromise may result in significant insta-
of the fibula and develops as a separate center of ossi- bility if removed. Fractures of the malleoli typically have
fication that fuses to the distal tibial epiphysis by 1 year significant displacement, making primary bone healing
of age. unlikely. Large fragments should be repaired rather than
Lateral malleolar fractures are usually associated with removed. Successful repair requires accurate anatomic
a fall or kick (Figure 5.86). A traumatic force from lateral reconstruction with internal fixation. Lag screw fixation
to medial on the limb fractures the LM. Common local- is considered sufficient to stabilize the fracture and
izing signs such as TC effusion and periarticular/periliga- counteract the distracting forces applied by the CLs.
mentous swelling occur soon after injury. Tensile forces Fragments of the LM larger than 3 cm are best reat-
applied by CL to the attachments on the malleoli frag- tached to the parent bone using 3.5‐mm cortical screws
ments probably contribute to displacement. Fragments placed in lag fashion. Large avulsion fractures of the
can rotate and displace distally. Ultrasonography is a MM can be repaired with one or two 4.5‐ or 5.5‐mm
very useful tool to determine the exact location of the cortex or cancellous screws placed in lag fashion. A full‐
fragment(s) and to assess the extent of injury to other limb cast is applied to provide mediolateral stability
structures. For example, a fragment from the LCL is often during recovery from anesthesia and maintained during
located within the dorsolateral pouch of the TC joint but the initial postoperative period. Nondisplaced fragments

A B

Figure 5.86. Lateral malleolar fractures are usually associated collateral ligament. The ultrasound image (B) demonstrates the
with a fall or kick that creates a traumatic force from lateral to fragment (arrows) and effusion within the lateral digital extensor
medial on the limb. The DP radiographic projection on the left (A) tendon sheath because of their close anatomical position.
demonstrates displacement of the fragment due to the pull of the