High-field magnetic resonance imaging enables diagnosis of central tarsal bone fractures in performance horses with lameness localized to the proximal metatarsus and tarsus.

Abstract

Objective: Central tarsal bone (CTB) fractures are challenging to diagnose, and cross-sectional imaging is required for definitive characterization and surgical planning. This retrospective case series aims to provide the first description of high-field (3-T) MRI characteristics of CTB fractures, concurrent pathology, and clinical presentation in 8 performance horses.

Animals: 8 horses (9 limbs) diagnosed with a CTB fracture on high-field MRI at one tertiary referral hospital between 2013 and 2023 were identified via electronic medical records search.

Clinical presentation: Quarter Horses (6 of 8) used for Western performance disciplines, a Lusitano (1 of 8) used for Dressage, and a Thoroughbred (1 of 8) used for polo, with ages ranging from 3 to 20 years (mean, 8.4 years), were included. Lameness onset was chronic in the majority of cases (5 of 8), with grades ranging from 3/5 to 4/5. Lameness was localized to the proximal metatarsus (4 of 6), distal tarsal joints (1 of 6), or tarsocrural joint (1 of 6). A suspected CTB fracture was identified on radiographs prior to MRI in only 1 limb.

Results: Fractures were complete (6 of 9) or incomplete (3 of 9) with a dorsomedial to plantarolateral orientation occurring from 36° to 62° medial to the sagittal plane (mean, 52°). There was severe sclerosis (9 of 9) and mild (4 of 9), moderate (4 of 9), or severe (1 of 9) bone edema-like signal associated with all fractures.

Clinical relevance: High-field MRI enabled diagnosis and detailed evaluation of CTB fracture configuration and concurrent bone and soft tissue pathology. Dorsomedial-plantarolateral oblique radiographic projections at approximately 50° medial to the sagittal plane may improve initial CTB fracture identification in performance horses.