Small Animal Radiology and Ultrasound: A Diagnostic Atlas and Text

C H A P T E R F O U R
The Appendicular Skeleton
THE radiographic diagnosis of bone and joint disease is composed of two processes:
description and interpretation of the lesion. Description of a lesion usually requires
at least two radiographs that are centered on the region of interest, carefully positioned,
properly exposed, and at right angles to each other. The radiographs should include
the joints that are proximal and distal to the lesion. For joint lesions, the radiograph should
be centered on the joint.
Radiographs generally are described by the path that the x-ray beam traverses.
Commonly used views include ventrodorsal, dorsoventral, dorsopalmar, dorsoplantar,
mediolateral, and lateromedial. 1 Several other views to evaluate specific areas of patient
anatomy have been described including some with joints under various stresses, which aids
in the evaluation of the integrity of specific ligaments or tendons. 2-11
Knowledge of normal musculoskeletal anatomy, especially with regard to the immature
animal, is essential for lesion recognition. 12-30 The location and dates of closure for the
growth plates can be very important in evaluating the radiograph (Table 4-1). 12
Comparison radiographs of the opposite limb can be extremely valuable (Fig. 4-1).
Knowledge of specific sites of sesamoid bones that are not present in every individual and
other anatomical details is also important. 13-30 477
A
B
Fig. 4-1 A 9-month-old male German Shepherd dog that has been lame in the right forelimb for 2
months. The dog resented manipulation of the elbow. A lateral radiograph of the right elbow (A) and
a comparison lateral radiograph of the left elbow (B) were obtained. A, There is increased density
involving the subchondral bone of the proximal right ulna (small open arrows). The coronoid process
is flattened and indistinct (large open arrow). There is a slight amount of bony proliferation with
remodeling of the proximal aspect of the anconeal process and irregularity involving the proximal
aspect of the radius (solid arrows). These changes in this elbow are more apparent when compared
with the normal left elbow. Diagnosis: Fragmented coronoid process.