MEDIAL FEMORAL CONDYLE SUBCHONDRAL LUCENCIES AND SUBCHONDRAL CYSTIC LESIONS IN YOUNG THOROUGHBREDS.

摘要

A range of radiographic defects are identified on the distal weight bearing surface of the medial femoral condyle (MFC) in young thoroughbred horses. They have been variably classified with either grading systems based on size and shape or radiographic measurements of size alone.1'3 Generally they are either smaller defects on the MFC which in this abstract will be referred to as subchondral lucencies (SLs>Wallis type 1, Santchi grade 2) or larger defects extending deeper into the condyle referred toas subchondral cystic lesions (SCLs) (Wallis type 2A/B, Santchi grade 4, 5). Their pathogenesis is not well understood, they likely develop from osteochondrosis or trauma, but may be caused by a combination of these processes.4"5 Subchondral bone lesions on the MFC can progress and enlarge from a SL to a SCL.6 The presence of SCLs in thoroughbred yearlings has been demonstrated to dramatically impact the horses value at public auction.7 Reports are conflicting with regard the impact SCLs have on futurecompetition and performance, but appear to affect the horses likelihood to compete as 2-3yros.7'8 In Australia the 2-3yro racing seasons provide both the greatest opportunities for prizemoney and future breeding value. SLs of varying sizes are relatively commonly seen in radiographs at public auctions (5.6-15%) both in Australia and New Zealand.8,9 The potential progression of SLs to SCLs and their impact on horses' saleability provide an environment in Australia where surgical techniques to improve radiographic appearance of SLs or SCLs, is accepted by breeders particularly in more valuable yearlings.