Department of Clinical Sciences of Companion Animals, University of Utrecht, Utrecht, Netherlands
The most common primary elbow lesion is a fragmented medial coronoid process (FCP). Yet radiographic diagnosis of coronoid pathology remains challenging and mainly depends on the experience of the observer. Consistent findings on ML views include a blurred and deformed cranial contour of the medial coronoid process (MCP), a reduced opacity of its tip, an increased opacity of the ulnar notch at the level of the MCP as well as an increased and/or incongruent joint space between humerus and radius. It is important to recognize that even minimal changes are usually pathognomonic for a FCP qualifying an overall score of at least ED 2 (moderate ED, coronoid disease/FCP indicated) according to the current International Elbow Working Group (IEWG) protocol regardless of the height of potential osteophyte formations. The severity of new bone formation is highly variable and some dogs may not show any new bone formation at all. If grading is based on the size of the osteophytes only, many elbows with FCP will be underscored and may even be considered free of ED.
Even with perfect radiographic quality and high observer experience radiographic readings may remain equivocal or debatable in rare cases - particularly when certain conformations of the medial coronoid process occur as has been noted in retriever dogs by the authors recently. In these cases computed tomography (CT) may be a highly useful tool to verify radiographic findings. Also diagnosing FCP radiographically may be based on subtle findings which may be difficult to convey to the dog owner. As a consequence an increasing number of appeals are filed and owners ask for a CT study to be included in the re-evaluation process. No standardized protocol for CT examination of the canine elbow has been proposed. IEWG plans to install a standardised protocol for appeal procedures, the use of cross-sectional imaging and the technical requirements of such studies.