Page 229 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

204 CHAPTER 1

VetBooks.ir of the cruciate, meniscal or collateral ligaments, and (collateral and cruciate ligaments) are severely torn,
instability and severe lameness will result. When such
desmitis of the patellar ligaments. A penetrating
injury into the synovial compartments can result in
malities are usually sufficient to make a diagnosis as
septic arthritis. Trauma to the articular cartilage is severe injury is present, fortunately palpable abnor-
frequently encountered. Abnormal cartilage cover- intra- articular analgesia of the stifle joints in this situ-
ing the medial femoral condyle (chondromalacia) is ation can be difficult to interpret.
discussed in the next section.
Differential diagnosis
Aetiology/pathophysiology OCD; articular fractures; septic arthritis; rupture of
It is suggested that injuries of the meniscus and the origin of the long digital extensor tendon and
associated ligaments are caused by a combination of peroneus tertius; femoral fractures.
crushing forces with rotation of the tibia and flex-
ion or extension of the stifle. Cruciate injuries are Diagnosis
possibly the result of sudden turning of the horse The reciprocal apparatus coordinates the movement
while the stifle is flexed. The medial collateral liga- of the whole limb and therefore it is impossible to
ment is more commonly affected than the lateral localise gait abnormalities to the stifle. Clinical find-
one. Ligament and meniscal injuries are most often ings at the level of the stifle may point to this region
seen in adult horses and a combination of soft-tissue as the potential site of pain, but careful examination
injuries may be present. Desmitis of the patellar lig- of the rest of the limb is still mandatory. Due to the
aments, usually the middle one, is rare and occurs unpredictable communication between the differ-
most commonly in jumping horses. This condition ent synovial compartments of the stifle joint, when
may also occur in horses with intermittent upward performing a joint block, it is important to anaesthe-
fixation of the patella or as a sequela to desmotomy tise all three compartments in order to localise the
of the medial patellar ligament. Blunt trauma to the pain. If lameness is severe, local analgesia should be
region can induce a variety of injuries. avoided. Radiography is useful to identify concurrent
bony injury. Ultrasonography is useful for imaging
Clinical presentation many soft-tissue conditions affecting the stifle region
Invariably, all affected horses are lame, but the degree (Figs. 1.390–1.393), but some lesions, in particu-
of lameness varies from subtle to severe depending on lar those affecting the cruciate ligaments, cannot be
the type, severity and duration of the injury. Effusion adequately visualised. Ultrasonography can also be
of any of the stifle joint compartments may be pal- useful to help identify lesions of the cartilage of the
pable, and signs of local inflammation may be present trochlear ridges of the distal femur and medial femo-
as well. It is important to remember that the stifle in ral condyle. Diagnostic arthroscopy is indicated if no
a horse is divided into three compartments: the femo- abnormalities are detected on any imaging modality
ropatellar joint, the lateral femorotibial joint and the and the lameness is localised to the stifle (Fig. 1.394).
medial femorotibial joint. It is common for the femo- Recently, MRI of the stifle has been performed under
ropatellar and medial femorotibial joints to commu- general anaesthesia using an open, low-field magnet,
nicate and, as these compartments are the most often and in the future this may provide further useful
affected by disease, they are where effusion is most information to identify soft-tissues lesions.
likely to be felt. Commonly, upper limb flexion tests
exacerbate the degree of lameness, with some horses Management/prognosis
resenting flexion of the affected limb. Intra-articular Mild soft-tissue injuries of the stifle may be treated
analgesia should greatly improve the degree of lame- with a combination of rest and intra-articular medi-
ness with injuries involving any of the joint compo- cation, with corticosteroids currently the most
nents; however, there are occasions when only a partial frequently used drug (e.g. 5–10 mg triamcinolone
improvement is noted. In a small number of cases evi- acetonide per affected joint compartment with care
dence of external injury or wounds may be present. If taken to avoid an excessive total dose). Horses with
one or several of the supporting ligaments of the joint stifle lameness often require a careful rehabilitation