Page 227 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

202 CHAPTER 1

VetBooks.ir 1.387 1.388

Fig. 1.388 Arthroscopic view of the upper half of the
medial side of the lateral trochlear ridge showing a large
Fig. 1.387 Arthroscopic view of the underneath of area of abnormal and loose cartilage associated with an
the patella with an osteochondrosis lesion visible in the osteochondrosis lesion. (Photo courtesy Graham Munroe)
distal half (upper part of image). The trochlear groove is
ventral. (Photo courtesy Graham Munroe)
may be recognised in young animals exercising in
the paddock. In some animals, the disease remains
appears to be important in terms of prognosis, with asymptomatic until later in life, when joint degen-
a significantly improved prognosis if the lesion is less eration, or an increase in athletic demands, leads
than 2 cm in length when measured arthroscopically. to a more pronounced synovitis and discomfort. In
Large lesions of the trochlear ridge in foals where sta- the majority of cases, lameness is mild or moderate
bility of the patellar is affected carry a poor prognosis. and acute, but in older animals it may be insidious
in onset. Effusion of the medial femorotibial joint is
SUBCHONDRAL OSSEOUS CYST-LIKE usually present but is not always easily detected.
LESIONS OF THE MEDIAL FEMORAL
CONDYLE Differential diagnosis
Femoropatellar joint OCD; meniscal tears; chon-
Definition/overview dromalacia of the medial femoral condyle; in older
The medial femoral condyle is one of the most com- animals OA.
mon sites in the horse to find osseous cyst-like lesions
(OCLLs), often referred to simply as bone cysts. The Diagnosis
lesions tend to form on the weight-bearing aspect of Affected animals present with hindlimb lameness
the condyle and affect the overlying articular car- with effusion of the medial femorotibial joint and
tilage, leading to synovitis and lameness. As with possibly a response to flexion of the proximal limb
OCD lesions of the femoropatellar joint, OCLLs as the only indications of the location of pathology.
may hasten joint degeneration and lead to OA. Diagnostic regional and intrasynovial analgesia is
therefore essential in isolating the site of discom-
Clinical presentation fort and to confirm the clinical significance of the
The condition is most often first recognised in young cyst. Radiographic examination of the stifle should
animals, particularly as they begin ridden exercise, demonstrate a radiolucent, flask-shaped lesion of the
although in more severely affected cases lameness subchondral bone of the medial femoral condyle,