Computed tomography features associated with fracture of the fetlock joint

This should lead to review and further studies on why these pre-fracture abnormalities occur which should lead to training regimens that protect these horses from this catastrophic event. Off hand, proper recovery times and exercise following training exercises might be the ticket, for more see Exercise physiology and conditioning.
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Post-mortem computed tomography features associated with fracture of the fetlock joint in racing Thoroughbreds

Equine Vet J. 2025 Feb 10. doi: 10.1111/evj.14465. Online ahead of print.
Authors
Catherine Beck 1 , Peta L Hitchens 1 , R Christopher Whitton 1
Affiliation

1 Melbourne Veterinary School, Faculty of Science, University of Melbourne, Melbourne, Victoria, Australia.

PMID: 39925247
DOI: 10.1111/evj.14465

Abstract

Background: Post-mortem studies have shown that fractures involving the metacarpophalangeal/metatarsophalangeal or fetlock joint are associated with focal areas of microdamage. Identification of computed tomography (CT) features consistent with microdamage and their association with fracture may aid in identification of horses at risk of fracture.

Objectives: To identify CT features associated with fracture of the metacarpophalangeal/metatarsophalangeal joint.

Study design: Retrospective cohort study.

Methods: Post-mortem CT images of 367 limbs from 157 Thoroughbred racehorses were graded for CT features. Multivariable logistic regression models were generated. Intraclass correlation coefficients of key CT features to assess intra and inter-rater reliability were calculated.

Results: The presence of lysis within the subchondral/trabecular bone underlying the lateral and, or, medial parasagittal groove (PSG) of the distal third metacarpus/tarsus (odds ratio [OR] 9.6; 95% confidence interval [CI] 4.3-21.3; p < 0.001) and sclerosis of the palmar subchondral and trabecular bone underlying the lateral and medial PSG that projected proximoaxially (OR 4.6; 95% CI 1.1-19.02; p = 0.03) were associated with condylar fracture. The presence of a proximal sesamoid bone (PSB) lytic lesion (OR 5.3; 95% CI 1.2-23.6; p = 0.03) and increasing medial PSB density (OR 1.02; 95% CI 1.00-1.03; p < 0.001) were associated with PSB fracture. Palmar osteochondral disease grade was not associated with condylar (p = 0.8) or PSB fracture (p = 0.09). Inter rater reliability was moderate for the presence of PSG lysis (ICC 0.7; 95% CI 0.6-0.8) and shape of sclerosis in the lateral condyle (ICC 0.6; 95% CI 0.5-0.8). Main limitations: The extent of lysis within the PSG and the volume of the PSB could not be as accurately obtained in limbs with multiple fracture fragments. Conclusions: CT examination of fetlock joints post-mortem identified changes associated with both metacarpal condylar fracture and PSB fracture in racehorses. These findings show that pre-race CT screening has the potential to reduce fracture rates. Keywords: condylar fracture; fetlock; horse; metacarpus; proximal sesamoid bone. © 2025 EVJ Ltd.