Magnetic resonance imaging‐detected adaptation and pathology in the distal condyles of the third metacarpus, associated with lateral condylar fracture in Thoroughbred racehorses

Abstract

SummaryReasons for performing the study: Lateral condylar (LC) fractures of the third metacarpus (McIII) are a common reason for euthanasia in racehorses, and may be the result of repetitive overloading or cumulative pathological change. Magnetic resonance imaging (MRI) allows monitoring of bone and cartilage to detect pathological and adaptive changes that may be precursors of fracture. Objectives: To describe bone and cartilage MRI features in the distal condyles of McIII of Thoroughbred racehorses, with and without condylar fracture. Hypotheses: 1) A greater degree of bone and cartilage adaptation or pathology will be seen in fractured McIIIs compared with their respective contralateral McIIIs. 2) Contralateral McIIIs will have a greater degree of bone and cartilage adaptation or pathology than McIIIs from control horses that did not sustain a LC fracture. Methods: The McIIIs from 96 horses subjected to euthanasia at racecourses were divided into 3 groups: Group 1: nonfractured bones from horses without LC fracture; Group 2: nonfractured bones from horses with unilateral LC fracture; and Group 3: fractured bones from horses with unilateral LC fracture. The MR images were examined and graded for bone and cartilage changes. Results: Nine percent of Group 1 (n = 9) and 11% of Group 2 bones (n = 5) had incomplete LC fractures. Focal palmar necrosis was most frequently detected in bones from Group 1 (12%) compared with Groups 2 (9%) and 3 (4%). The prevalence of bone and/or cartilage abnormalities tended to increase from Group 1 to Group 2 to Group 3. Conclusions: Magnetic resonance imaging is able to detect cartilage and bone changes that may be associated with LC fracture. There was no significant difference in bone/cartilage changes between bones from Groups 1 and 2, despite increased pathology in Group 2 bones. Potential relevance: Periodic monitoring of bone and/or cartilage changes in distal McIII of Thoroughbred racehorses may help to prevent catastrophic LC fractures.

Does subchondral bone of the equine proximal phalanx adapt to race training?

“…; Tranquille et al. ) both Horserace Betting Levy Board funded)] for which ethical approval had been obtained (RC and CF bones) or after informed consent from the owner (UC bones).…”

Metacarpus/metatarsus

“…41,46,52,61 In racehorses, the subchondral bone in the region of the condyles undergoes intense adaptive and maladaptive remodeling in response to the strains of high-speed exercise. [61][62][63] There is ample evidence, both grossly and histologically, of degenerative changes in the subchondral bone associated with lateral condylar fractures [64][65][66][67] (Fig. 16.10).…”

Epidemiology of orthopedic diseases in athletic horses

“…Tranquille and colleagues 74 have identified significant differences in adaptation and pathology in bones with and without lateral condylar fracture that may be predictive of lateral condylar fracture of the third metacarpus. Information on the types and locations of likely injuries or diseases which are most common in different types of sports horse will enhance the clinicians ability to make those early diagnoses.…”