Magnetic resonance imaging evaluation of 264 horses with foot pain: the podotrochlear apparatus, deep digital flexor tendon and collateral ligaments of the distal interphalangeal joint.
BACKGROUND
To improve understanding of the interrelationships between injuries of the podotrochlear apparatus and deep digital flexor tendon (DDFT).


OBJECTIVE
There is a difference in frequency of different types of lesions at different anatomical sites of the DDFT. Lesions of the collateral sesamoidean ligament (CSL), distal sesamoidean impar ligament (DSIL), distal interphalangeal (DIP) joint and navicular bursa are seen in association with lesions of the navicular bone.


METHODS
The magnetic resonance (MR) images of 264 horses with unilateral or bilateral foot pain were analysed and graded. Descriptive statistics were performed to establish the frequency of occurrence of DDFT lesion types at different anatomical levels, and lesions of the CSL, DSIL, navicular bursa, DIP joint and collateral ligaments (CLs) of the DIP joint. A Chi-square test was used to test for a difference in the proportion of navicular bone grades between limbs with and without DDFT lesions at each level, and to compare navicular bone grades for limbs with and without each of DSIL, CSL, navicular bursa or DIP joint lesions.


RESULTS
Lesions of the DDFT occurred in 82.6% of limbs, occurring most commonly at the level of the CSL (59.4%) and the navicular bone (59.0%). Core lesions predominated at the level of the proximal phalanx (90.3%), whereas at the level of the CSL and navicular bone core lesions, sagittal splits and dorsal abrasions were most common. There was a positive association between DDFT lesions and navicular bone pathology involving all aspects of the bone. Lesions of the DSIL (38.2% limbs) were more common than those of the CSL (10.5%), but the presence of either was associated with abnormalities of the navicular bone, especially involving the proximal or distal borders and the medulla.


CONCLUSIONS
There are close interactions between injuries of the components of the podotrochlear apparatus, the DDFT, the navicular bursa and the DIP joint. Further knowledge about the biomechanical risk factors for injury may have importance for both disease prevention and management.
Dyson
S
S
Centre for Equine Studies, Animal Health Trust, Lanwades Park, Kentford, Newmarket, Suffolk CB8 7UU, UK.
Murray
R
R
D000818:Animals; D017885:Collateral Ligaments / Q000473:pathology; D005534:Foot Diseases / Q000175:diagnosis / Q000473:pathology / Q000662:veterinary*; D006724:Hoof and Claw / Q000473:pathology*; D006734:Horse Diseases / Q000175:diagnosis* / Q000473:pathology; D006736:Horses; D007794:Lameness, Animal / Q000175:diagnosis* / Q000209:etiology / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods / Q000662:veterinary*; D010146:Pain / Q000209:etiology / Q000662:veterinary; D012720:Severity of Illness Index; D013710:Tendons / Q000473:pathology; D014033:Toe Joint / Q000473:pathology*