Catastrophic fracture of the lateral condyle of the third metacarpus/metatarsus in UK racehorses – fracture descriptions and pre-existing pathology T.D.H. Parkin a, * , P.D. Clegg a , N.P. French a , C.J. Proudman a , C.M. Riggs b , E.R. Singer a , P.M. Webbon c , K.L. Morgan a a Department of Veterinary Clinical Science, University of Liverpool Veterinary Teaching Hospital, Leahurst, Neston CH64 7TE, UK b The Hong Kong Jockey Club, Sha Tin Racecourse, NT, Hong Kong c The Jockey Club, 42 Portman Square, London W1H 0EN, UK Accepted 2 October 2004 Abstract The characteristics of, and pre-existing pathology associated with 75 cases of fatal lateral condylar fracture sustained by Thoroughbreds while racing in the UK were described. Cases were identified from 220 cases of fatal distal limb fracture submitted as part of studies designed to identify risk factors for all fatal distal limb fractures. Fractures were most common in hurdle races and affected the right forelimb twice as often as the left forelimb. Fracture dimensions were similar to previous reports, however there was a much greater prevalence of articular and diaphyseal comminution and of concurrent fractures in the current report. Pre-existing pathology was particularly common in the medial and lateral parasagittal grooves of the distal articular surfaces of the third metacarpus/metatarsus. The degree of this pathology was not associated with horse age, length of career or number of career starts. Ó 2004 Elsevier Ltd. All rights reserved. Keywords: Thoroughbred; Racing; Lateral condyle; Fractures; Pathology 1. Introduction In the UK, fractures of the distal limb are the most common reason for equine euthanasia in all types of race (McKee, 1995). The lateral condyle of the distal articular surface of the third metacarpus (MCIII) is the most com- mon site of fracture (Parkin et al., 2004c). In the USA, only proximal sesamoid bone fractures are more com- mon (Johnson et al., 1994; Mohammed et al., 1991; Pelo- so et al., 1994). Several studies have described large numbers of cases of lateral condylar fracture (Bassage and Richardson, 1998; Ellis, 1994; Meagher, 1976; Rick et al., 1983; Zekas et al., 1999a). All of these reports have been based on cases submitted to veterinary hospitals for treatment and include details of fracture configurations and dimensions, concurrent pathology and treatment options. No equivalent description of a series of cases considered severe enough to warrant immediate eutha- nasia has previously been reported. It has been hypothesised that lateral condylar frac- tures are the end stage of a series of fatigue related events (Kawcak et al., 1995; Riggs, 1999). Micro- and macroscopic investigations have documented character- istic patterns of pre-existing articular cartilage and sub- chondral pathology associated with lateral condylar fractures (Radtke et al., 2003; Riggs et al., 1999; Stepnik 1090-0233/$ - see front matter Ó 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.tvjl.2004.10.009 * Corresponding author. Tel.: +44 151 794 6079; fax: +44 151 794 6028. E-mail address: timp@liv.ac.uk (T.D.H. Parkin). www.elsevier.com/locate/tvjl The Veterinary Journal 171 (2006) 157–165 The Veterinary Journal