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

Abstract

(1) Background: Parasagittal groove (PSG) changes are often present on advanced imaging of racing Thoroughbred fetlocks and have been suggested to indicate increased fracture risk. Currently, there is limited evidence differentiating the imaging appearance of prodromal changes in horses at risk of fracture from horses with normal adaptive modelling in response to galloping. This study aims to investigate imaging and gross PSG findings in racing Thoroughbreds and the comparative utility of different imaging modalities to detect PSG changes. (2) Methods: Cadaver limbs were collected from twenty deceased racing/training Thoroughbreds. All fetlocks of each horse were examined with radiography, low-field magnetic resonance imaging (MRI), computed tomography (CT), contrast arthrography and gross pathology. (3) Results: Horses with fetlock fracture were more likely to have lateromedial PSG sclerosis asymmetry and/or lateral PSG lysis. PSG lysis was not readily detected using MRI. PSG subchondral bone defects were difficult to differentiate from cartilage defects on MRI and were not associated with fractures. The clinical relevance of PSG STIR hyperintensity remains unclear. Overall, radiography was poor for detecting PSG changes. (4) Conclusions: Some PSG changes in Thoroughbred racehorses are common; however, certain findings are more prevalent in horses with fractures, possibly indicating microdamage accumulation. Bilateral advanced imaging is recommended in racehorses with suspected fetlock pathology.

Radiomics Modeling of Catastrophic Proximal Sesamoid Bone Fractures in Thoroughbred Racehorses Using μCT

“…This work suggests that radiomic features from resampled μCT data comparable to the voxel dimensions in conventional CT could be used in modeling the risk of fracture in PSBs. Other non-invasive imaging methods such as MRI, nuclear imaging, and infrared spectroscopy are able to detect lesions and abnormalities before the onset of gross disease [ 8 , 9 , 33 , 34 , 35 , 36 ]. Recently, a commercial option has been proposed for obtaining CT images in anesthetized standing horses [ 7 ].…”

Fractures in Thoroughbred racing and the potential for pre‐race identification of horses at risk

“…A more recent study that screened the fetlocks of post‐mortem specimens from racehorses using an array of different imaging modalities reported that horses that had sustained a fetlock fracture were more likely to have lateromedial asymmetry of the degree of sclerosis of bone deep to the parasagittal groove and/or areas of lysis in the same region 128 …”

“…127 A more recent study that screened the fetlocks of post-mortem specimens from racehorses using an array of different imaging modalities reported that horses that had sustained a fetlock fracture were more likely to have lateromedial asymmetry of the degree of sclerosis of bone deep to the parasagittal groove and/or areas of lysis in the same region. 128 While studies have indicated that increased density of cancellous bone below articular surfaces is associated with bones of the distal limb that sustain fractures, 69,129 no prospective studies have been reported to explore the value of this observation as a predictive tool.…”

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

“…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.…”

“…Although differences in the palmar condyles of the distal metacarpal or third metacarpal bone and the proximal sesamoid bones between racehorses that have and have not sustained metacarpal or tarsal or proximal sesamoid bone fracture have been documented on both CT and MRI, there is currently no reliable way to differentiate changes that are a normal response to training and changes that are indicative of pathology that will likely lead to catastrophic injury in an individual horse. 84,[94][95][96][97][98][99][100][101][102] As of now, CT and MRI are not appropriate as a clinical screening tool for predicting impending breakdown injuries, but work is ongoing. Positron emission tomography also shows promise in this area, and the reader is referred to a companion Currents in One Health by Spriet, AJVR, July 2022, for further information.…”