Kulendra E, Tivers M, de la Puerta B.
IntroductionlPurpose: Computed tomography (CT) is routinely used to examine the elbows of dogs with suspected medial coronoid process (MCP) disease; however, there is poor correlation between CT signs and arthroscopic findings in these patients. The aim of this study was to elucidate the relationship between CT signs and arthroscopic findings in dogs with MCP disease by comparing CT images obtained pre- and post-arthroscopic treatment.
Methods: Prospective cross-sectional study of dogs with clinical signs of elbow pain having arthroscopic treatment for suspected MCP disease. The appearance of the MCP, with emphasis on fissures and fragmentation, was compared in pre- and post-operative CT images and the differences correlated with the arthroscopy reports.
Results: 45 dogs (72 elbows) were studied. Median age was 15 months (range 7-117 months). There were 31 males and 14 females. The most frequent breed was Labrador retriever (n=20). Fragments were removed arthroscopically from the MCP in 61 (85%) elbows, 10 (14%) elbows had arthroscopic signs of chondromalacia affecting the MCP, and one elbow had humeral osteochondritis dissecans. Pre-operative CT images showed articular calcified bodies compatible with fragments in 34/61 (56%) elbows and signs of fissures affecting the MCP in 16/61 (26%) elbows from which fragments were subsequently removed arthroscopically. Of the 34 elbows with fragments in pre-operative CT images, post-operative CT images demonstrated complete removal of fragments in 15 (44%), reduced size and/or number of fragments in 13 (38%), and no change in 6 (18%) instances. Fragments were visible only in post-operative CT images in 8/72 (11%) elbows. Evidence of debridement of subchondral bone was evident in post-operative CT images in 21/50 (42%) elbows subjected to that procedure.
Discussion/Conclusion: MCP fragmentation and/or chondromalacia are very prevalent in dogs with signs of elbow pain. Sensitivity of CT for fragments is moderate. Arthroscopy did not result in removal of all suspected fragments identified by CT, and some lesions suspected to be fragments were reduced in size by debridement rather than removed. Each of these findings suggests that articular calcified bodies identified by CT are not always visible arthroscopically, for example because they are covered by cartilage or beyond the range of the arthroscope; some may represent lesions not associated with the MCP, such as dystrophic calcification affecting the synovial membrane or annular ligament. The appearance of fragments only in some post-operative CT images suggests that the act of debriding the MCP can itself cause fragmentation.
This study was funded by PetSavers, a division of the British Small Animal Veterinary Association. www.petsavers.org.uk