Developmental orthopedic disease of the elbow is a common condition with complex causes that affects many large-breed dogs. Specific conditions include fragmented coronoid process, osteochondrosis, ununited anconeal process, and humeral intracondylar fissure. The most commonly used diagnostic technique is radiography, although computed tomography is sometimes needed.<\/p>\n
Take-Home Points<\/strong><\/p>\n Because the canine cubital (elbow) joint is a complex joint, developmental abnormalities of this joint are a common cause for lameness in young dogs. Dysplasia involving the cubital joint includes a group of diseases such as fragmentation of the medial coronoid process, osteochondritis <\/span>dissecans (OCD) of the medial humeral condyle, and ununited anconeal process (UAP), as well as incongruity in the joint. Additionally, humeral intracondylar fissures (HIFs) can occur either alone or in combination with other developmental abnormalities. The first diagnostic imaging modality chosen for evaluating developmental orthopedic disease in the canine elbow is typically radiography.<\/span><\/p>\n The most common developmental disorder involving the canine elbow joint is medial coronoid process disease (MCPD), previously referred to as fragmented coronoid process (FCP).1-5<\/sup> MCPD is a separate osseocartilaginous fragment, fissure, or abrasion involving the cartilage and subcondylar bone of the medial coronoid process of the ulna.1-5<\/sup><\/span><\/p>\n MCPD most commonly affects medium- and large-breed dogs; incidence is higher in male dogs. The most common breeds for which it is reported include Bernese mountain dogs, English and bull mastiffs, German shepherds, Irish wolfhounds, Rottweilers, and Saint Bernards.6,7<\/sup> The etiology is not completely known, but several theories have been proposed. These theories include joint incongruity (dyssynchronous growth of the radius and ulna) in the early growing phase, genetics, abnormal development of the trochlear notch, and osteochondrosis. The cause is likely multifactorial. Regardless, the result is development and progression of osteoarthrosis, particularly involving the medial compartment (humeral\u2013ulnar articulation) of the elbow.5<\/sup><\/span><\/p>\n Dogs with MCPD often exhibit lameness as early as 4 to 12 months of age. The onset of lameness is often insidious and will vary from a mild to severe weight-bearing lameness that is worsened with activity.5<\/sup> The affected leg is often held with the elbow adducted and the paw externally rotated. Joint effusion is rarely palpable, but pain can be elicited by direct palpation over the region of the medial coronoid process. Pain can also be elicited by supination of the antebrachium when the elbow is held in flexion.5<\/sup> As osteoarthrosis progresses, the medial compartment of the elbow will become thicker and the elbow range of motion will decrease.2,3,5<\/sup><\/span><\/p>\n For radiographic diagnosis of MCPD, a minimum of 3\u00a0projections should be obtained: neutral mediolateral, flexed mediolateral, and craniocaudal (<\/span>FIGURES 1\u20134<\/b><\/span>). For the lateral projections, it is critical to ensure that the beam is directed down the axis of rotation of the elbow so that the humeral condyle is not obliqued. An additional 25\u00b0 lateral\/caudomedial view may help to outline the medial coronoid process.1,6,8<\/sup> <\/span><\/p>\n\n
Fragmented Coronoid Process<\/h2>\n
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Figure 1A. Positioning for a neutral lateral radiograph of the elbow joint. In the neutral lateral view, the elbow angle is 120\u00b0.<\/span><\/a><\/div><\/div>Figure 1B. Positioning for a flexed lateral radiograph of the elbow joint. In the flexed lateral view, the inside angle is approximately 45\u00b0.<\/span><\/a><\/div><\/div>Figure 1B. Positioning for a craniocaudal radiograph of the elbow joint. In the craniocaudal lateral view, the elbow is internally rotated to achieve a straight craniocaudal view, identified when the olecranon is centered over the humeral condyle.<\/span><\/a><\/div><\/div>Figure 2. Lateral radiograph of a normal elbow with anatomic markers. The orange line outlines the medial coronoid process, which is well delineated and has a concave contour coming to a point at the cranial aspect. The white line outlines the lateral coronoid process. The blue line outlines the anconeal process. The anconeal process should have a smooth proximal border. The white and orange arrowheads point to the medial and lateral epicondyles, respectively. The medial epicondyle overlaps the trochlear notch (asterisk). In a well-positioned view, there is the appearance of concentric rings centered at the humeral condyle. The lateral view is the best view for evaluating congruity of the elbow. The radiolucent joint should be uniform surrounding the humeral condyle.<\/span><\/a><\/div><\/div>