Small Animal Radiology and Ultrasound: A Diagnostic Atlas and Text

570 Small Animal Radiolo g y and Ultrasono graphy
A
B
Fig. 4-121 A 5-month-old female German Shepherd dog with a left foreleg lameness of 2 weeks duration.
Lateral (A) and flexed lateral (B) radiographs of the left foreleg were obtained. A radiolucent line
separates the anconeal process from the proximal ulna (arrows). This is most obvious in the flexed lateral
radiograph. The radiolucent line is hidden by the medial epicondyle of the humerus in the straight
lateral view. Diagnosis: Ununited anconeal process. Flexion of the elbow is extremely important in
evaluating an animal for ununited anconeal process, because the lesion is more apparent when the
joint is flexed. The ununited anconeal process is visible on the straight lateral projection.
nose definitively on survey radiographs. 549-566 Fragmented coronoid process often affects
both ulnas, although clinical signs may be unilateral. The flexed lateral view of the elbow is
the most commonly used view in attempting to make the diagnosis. The medial coronoid
process usually is viewed most clearly on a slightly supinated anteroposterior view. It also
may be seen when viewed through the radial head on the lateral view. Frequently, the coronoid
fragment will not be identified specifically. Compared with other radiographic techniques,
CT has shown the highest accuracy, sensitivity, and negative predictive values in
making the diagnosis. 564
Among the earliest radiographic signs that will be seen is mild osteophytosis on the
horizontal, or proximal, aspect of the anconeal process. As the condition progresses,
endosteal sclerosis of the ulna immediately deep to the coronoid processes just caudal
and distal to the semilunar notch and a widened humeroulnar joint space may be seen.
Finally, signs of degenerative joint disease may be seen, including osteophytes on the
cranial proximal radius, medial humeral epicondyle, proximal margin of the anconeal
process, or coronoid process, but typically not affecting the lateral surfaces. The
degenerative changes, including the specific pattern of osteophytosis noted above, may
be highly suggestive of the diagnosis and may be the only radiographic findings noted
(Fig. 4-123). These usually will progress despite surgical intervention. 565-567 The separate
coronoid fragment rarely is identified by radiography, because it usually occurs on
the lateral aspect of the medial coronoid process (Fig. 4-124). The medial humeral
condylar lesion of osteochondrosis may be observed concomitantly with fragmented
coronoid process.
RETAINED CARTILAGE CORE. Retention of endochondral cartilage occurs in young,
large-breed, and giant-breed dogs. 397,568,569 Although any long bone may be involved, the
distal ulna is affected most frequently. An inverted radiolucent cone is seen extending proximally
from the distal ulnar physis into the metaphysis (Figs. 4-125 and 4-126). Irregular
metaphyseal radiolucencies and physeal widening may be observed in other bones.
Although the lesion usually is without clinical significance and disappears as normal bone
modeling occurs, growth retardation and angular limb deformities may result. Irregular