Summary
Objective: To assess movement of ulnar segments radiographically, following proximal and midshaft
ulnar osteotomy or ostectomy after arthroscopic treatment for dogs diagnosed with
medial coronoid disease.
Methods: Fragmentation and cartilage wear were treated arthroscopically and the presence of
incongruity confirmed. Osteotomies were performed at the mid-point or proximal third
of the length of the ulna. The distance of separation between the ulnar segments and
the adjacent radius were measured and followed by serial radiographs postoperatively
until healing had occurred.
Results: Proximal oblique osteotomies located at one-third the length of the ulna were associated
with the most movement of the ulnar segments, most notably of the proximal segment.
Osteotomies or ostectomies performed in the middle demonstrated less segmental movement
and on average, slightly longer time to heal. Movement of the ulnar segments in both
groups occurred immediately, and then peaked at two to four weeks postoperatively,
tending to plateau thereafter.
Clinical significance: Radioulnar incongruity is considered a facet of the aetiopatho-genesis of canine
medial coronoid disease. This creates abnormal loads and focal wear along the medial
coronoid process. Performing an oblique osteotomy at a location measured at the proximal
third of the length of the ulna allows increased movement of the proximal segment,
which may result in unloading of the medial compartment. Performing an osteotomy or
ostectomy distally dampens segmental movement due to constraint of the interosseous
ligament. These findings suggest that a proximal oblique osteotomy at this location
creates immediate favourable movement with low morbidity.
Keywords
Ulnar osteotomy - medial coronoid disease - radioulnar incongruity
