Page 722 - Adams and Stashak's Lameness in Horses, 7th Edition

688 Chapter 5

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A B
Figure 5.90. Lateral (A) and skyline (B) views demonstrating a fragmentation of PTT lesion (arrows). This fragmentation does not appear
to be a risk factor for the development of lameness but must be differentiated from OC that develops on the plantar trochlear ridges.

joint, the superficial CLs are under tension while the Ultrasonographic evaluation can be quite helpful to
limb is extended and relaxed while the limb is flexed, identify CL injury and define the type and severity of the
whereas the short CLs are tensed only when the tarsus is injury. The ultrasonographic appearance of the CLs
flexed. Therefore, the short CLs should be examined should always be compared with the opposite CL, and
while the leg is flexed. this should always be used as a reference for normal.
CL injury of the TC joint most often occurs due to Injury can change the size, shape, linearity, and architec-
some form of traumatic injury. 15,131 Lameness varies ture (appearance) of these structures. Serial US examina-
from mild to severe, depending on the degree of damage. tions are critical to monitor the repair process and to
Hindlimb proximal limb flexion significantly worsens evaluate healing. The malleolar insertion of the CLs
the lameness. Physical exam findings usually include tar- should be carefully evaluated in longitudinal view as
sal swelling with edema and/or fibrosis localized over changes can often at this location. Chronic injury may be
the medial CL (MCL) or lateral CL (LCL) region. The recognized as calcification (enthesis new bone) within
presence of TC effusion often occurs but the amount can the insertion of the CL. Insertional change can also occur
be quite variable. Desmitis associated with the enthesis in the short CL attachment onto the talus. Treatment for
of the CLs is often performance limiting. The diagnosis the disease is restriction of exercise for 2–3 months.
is usually made with a combination of radiographic A gradual reintroduction to exercise is predicated on the
and ultrasonographic examinations. Stress radiographic improving sonographic appearance. The prognosis is
examination may occasionally be necessary to more favorable for resolution after a period of rest.
effectively demonstrate instability associated with the Desmitis of the CLs, particularly the long CL, has
MCL and/or LCL. The initial radiographic exam of been described. 34,35,131 Injury to the CLs are thought to
acute injuries often only reveals soft tissue swelling, but occur with twisting and torqueing of the tarsus while
by 6–8 weeks after the injury enthesophytes may become the lower limb is fixed to the ground. Increasing tensile
evident along the origin and attachment sites of the CLs. stress (and probably the rate at which it is loaded) within
Fragmentation of the malleolar attachment of the CL the CLs may lead to fractures of the malleoli. High loads
attachment (most often the LM of the sLCL) can occa- are felt to develop within the sMCL/sLCL when the
sionally occur. horse falls on the lower limb while it is flexed. Initial
Enthesopathy of the lLCL and less commonly the treatment involves stall rest, cold water therapy, topical
sLCL has been reported in STB racehorse. Pacers were treatment (diclofenac or dimethyl sulfoxide with or with-
15
found to be more at risk of this condition than trotters. out corticosteroids), and systemic NSAIDs. Rehabilitation
Distension of the TC joint capsule and subtle, localized will require increasing periods of controlled exercise
soft tissue swelling were present, and lameness improved determined by an improving ultrasonographic appear-
with analgesia of the TC joint. Scintigraphy was also ance of the injured structure. Prognosis depends on the
utilized to show focal, intense IRU on the lateral aspect severity of injury and effective treatment and rehabilita-
of the calcaneus, and enthesopathy of the CL was tion. Horses with moderate injuries (and develop exten-
detected radiographically. The authors of that study sive periosteal new bone) have been able to return to full
theorized that cyclic stress associated with the speed of athletic function, although some residual enlargement of
racing was responsible for the injury. Local injections the hock has persisted.
with MPA and sarapin resulted in improvement in the Injuries to the CLs that exist within the intrasynovial
lameness. space of the TC joint may be difficult to accurately