Validation of standing cone beam computed tomography for diagnosing subchondral fetlock pathology in the Thoroughbred racehorse

Abstract

Background Subchondral bone pathology is common in Thoroughbred racehorses and believed to precede more serious injury. Early identification of pathology is critical to allow for intervention. Objectives To determine interobserver variability of fetlock subchondral bone lesions using cone beam and fan beam computed tomography (CBCT, FBCT) and to validate a robotics‐controlled CBCT to identify fetlock subchondral bone pathology in the Thoroughbred racehorse. Study design Prospective cohort study. Methods FBCT and CBCT images were acquired of 25 metacarpo‐/metatarsophalangeal joints of Thoroughbred racehorses. Images were analysed for subchondral bone lesions commonly identified in Thoroughbred fetlocks by an imaging specialist and surgery specialist. Interobserver and intermodality equivalence were determined with a Pearson correlation analysis and Bland‐Altman equivalence test. Results Interobserver FBCT correlation was significant (P < .05) for 19 of 25 variables (Pearson R mean 0.77). Concordance was significant for all 25 variables (Bland Altman average difference 0.28 ± 0.21 mm). Interobserver CBCT correlation was significant for 21 of 25 variables (Pearson R mean 0.73). Concordance was significant for all variables (Bland Altman average difference 0.07 ± 1.90 mm). Intermodality (FBCT vs CBCT) correlation and concordance was significant for all variables as interpreted by the radiologist (Pearson R mean of 0.72, Bland Altman average difference 0.21 ± 0.47 mm). Intermodality correlation was significant for 19 of 25 variables as interpreted by the surgeon (Pearson R mean of 0.72). Concordance was significant for all variables (Bland Altman average difference 0.49 ± 0.52 mm). Main limitations Neither FBCT nor CBCT images were compared with other imaging modalities/histopathology; limited number of cases included; inconsistent agreement of small lesions in specific categories. Conclusions Standing CBCT is a valid diagnostic modality to identify subchondral bone lesions in Thoroughbred fetlocks. This technology may provide valuable information regarding the development and progression of fetlock pathology and yield insight into predisposing factors leading to more severe pathology.

Imaging and Gross Pathological Appearance of Changes in the Parasagittal Grooves of Thoroughbred Racehorses

“…Equally, this study did not investigate standing CT. Standing systems are likely to have more motion artefact and lower image quality than the helical CT system used in this study [ 50 ].…”

Computed tomographic assessment of fracture characteristics and subchondral bone injury in Thoroughbred racehorses with lateral condylar fractures and their relationship to outcome

“…Subchondral bone lesions were defined as central areas of linear, oval or crescentic hypodensites (consistent with bone lysis) within regions of hyperdensity (consistent with sclerosis) in the palmar or plantar distal condyles 19,23 . To further assess the SBI lesions, the width (axial to abaxial), length (palmar/plantar to dorsal), and height (proximal to distal) of the lesions were measured using multiplanar reconstructions of the fetlock as previously described 24 . Whether the fracture line propagated through the SBI lesion was also noted.…”

“…19,23 To further assess the SBI lesions, the width (axial to abaxial), length (palmar/plantar to dorsal), and height (proximal to distal) of the lesions were measured using multiplanar reconstructions of the fetlock as previously described. 24 Whether the fracture line propagated through the SBI lesion was also noted.…”

When radiography and ultrasonography are not enough: the use of computed tomography and magnetic resonance imaging for equine lameness cases

“…Due to the shorter scans time as compared with MRI, motion is less of a problem with standing CT, but is still an issue. [25][26][27][28][29] There are also differences between cone beam and fan beam CT systems. In a basic sense, fan bean CT collects thin slices of information and cone beam CT collects a volume of information.…”

“…9,13,29,53,73,[78][79][80] CT and MRI are superior to radiography in the diagnosis of bony injury in the fetlock region in a variety of types of horses. 4,6,9,10,13,25,41,53,73,78,[81][82][83][84][85] Many of these types of bony injuries are suspected to originate from an accumulation of damage rather than a 1-time event, so the use of CT/MRI to identify pathology sooner could potentially prevent more severe or permanent damage as well as providing a more prompt, accurate diagnosis. [86][87][88] In sport horses, subchondral bone disease often presents as a bone marrow lesion or fissure fracture in the distal metacarpal or third metacarpal bone or the proximal part of the first phalanx.…”