Frequency distributions of 174 fractures of the distal condyles of the third metacarpal and metatarsal bones in 167 Thoroughbred racehorses (1999–2009)

Abstract

SummaryReasons for performing study: Although fractures of the metacarpal and metatarsal condyles are the most common long-bone fractures of Thoroughbred horses in training, limited data on variations in morphology and incidence have been published. Additionally, grouped analyses of previous studies from the UK and USA would permit comparison between study groups and the creation of a substantial pool of international data. Methods: Retrospective analysis of case records of horses with fractures of the distal condyles of third metacarpal/metatarsal bones seen over the last 10 years at Newmarket Equine Hospital. The current series was compared with a prior series from the UK; pooled analyses of these, and series from the USA were also compared. Results: One hundred and seventy-four fractures were identified in 167 racehorses. The current series contained a significantly lower proportion of medial condylar fractures than in a similar population 17 years earlier. Fractures that originated more abaxially tended to be shorter, and a significant proportion of lateral condylar fractures arose outside of the condylar groove. There was also some apparent seasonality of fractures of the lateral condyles in 2-year-old horses, but not so in older horses or those with medial condylar fractures. Conclusions and potential relevance: A substantial portion (approximately 50%) of fractures in the present series cannot be explained by unifying theories of aetiopathogenesis, which suggest that fractures usually arise within the condylar groove, as a focus of cumulative fatigue and failure of adaptation of bone. A separate aetiopathogenesis may be responsible for a proportion of condylar fractures encountered in racehorses, and further work is required to elucidate this. Changes in the number of medial condylar fractures encountered may reflect the introduction of artificial racing and training surfaces, and also may reflect changes in the age demographic of horses racing in the UK since the introduction of year-round 'all-weather' racing.Keywords: horse; Thoroughbred; racehorse; third metacarpal/metatarsal bone; condyle; fracture AbbreviationsMcIII: Third metacarpal bone MtIII: Third metatarsal bone IntroductionThe metaphyseal and epiphyseal anatomy of the third metacarpal (McIII) and metatarsal (MtIII) bones is similar. The distal epiphyses consist of 2 condyles separated by a sagittal ridge, which is angled slightly lateral from palmar/plantar to dorsal. The medial condyle is larger in both mediolateral and dorsopalmar/plantar planes. Its distal articular surface is perpendicular to the long axis of the bone, while that of the lateral condyle has a slight proximal axial incline. The articular surfaces of both condyles bear a slight lateromedial transverse (frontal plane) ridge at their most distal point. This marks a change in the radius of curvature of the epiphysis such that the palmar/plantar articular surfaces of the condyles are flatter than the dorsal surfaces. The latter represent the contact area for the proximal phalanx ...

Computed Tomographic Imaging of Subchondral Fatigue Cracks in the Distal End of the Third Metacarpal Bone in the Thoroughbred Racehorse Can Predict Crack Micromotion in an Ex-Vivo Model

“…More work is needed to comprehensively understand the relationship between athletic history and subchondral fatigue injury. Clinically, condylar fractures are more common in younger horses that may not have an extensive racing history [1], [3], [25].…”

“…Only thoracic limbs were used for this study. Condylar fractures most commonly affect the thoracic limbs [2], [3], [24], [25]. Limbs were transected at the level of the carpus, sealed in plastic bags, and stored at -20C until needed.…”

Diagnostic and Surgical Arthroscopy of the Metacarpophalangeal and Metatarsophalangeal Joints

“…This should include flexed dorsopalmar/plantar projections (flexed dorsal distal 35 degrees-proximal palmar/ oblique is the technique of choice) to image the palmar/plantar subchondral bone without superimposition (Jacklin & Wright, 2012) (Fig. 5-56).…”

Introduction

“…Further information has been recently published on fractures of the metacarpal and metatarsal condyles (Wright and Nixon, 2013;Jacklin and Wright, 2013) emphasizing the importance of articular congruency to outcome. Arthroscopically guided repair of midbody proximal sesamoid bone fractures was described, and results were reported by Busschers et al (2008), representing a substantial advance in the management of uniaxial fractures.…”