Best modality for navicular intrabursal pathology?

Equine Vet J. 2025

Author

Obi Veterinary Education
March 19, 2026

Grigorios Maleas, Natasha Werpy, Zoë Joostens, Bruce Bladon, Kerstin Gerlach, Mahmoud Mageed

Background
Navicular intrabursal pathology (NIP), a frequent cause of forelimb lameness in horses, involves lesions within the podotrochlear apparatus, including the deep digital flexor tendon (DDFT), navicular bone fibrocartilage, and intrabursal adhesions. While magnetic resonance imaging (MRI) is the reference standard for non-invasive evaluation, its cost and limited accessibility necessitate the use of alternative imaging modalities such as ultrasonography and bursography. This study aimed to compare the diagnostic accuracy of ultrasonography, bursography, and standing low-field MRI against bursoscopy, which served as the gold standard, for detecting NIP.

Methods
This was a prospective, blinded clinical study involving 21 feet from 17 client-owned horses with confirmed foot pain. Horses underwent ultrasonography, standing low-field MRI (0.27 T), and bursography, followed by diagnostic bursoscopy within three weeks. Lesions assessed included DDFT dorsal fibrillations and splits, navicular bone fibrocartilage defects, and intrabursal adhesions. Independent, blinded specialists evaluated each modality, and diagnostic metrics (sensitivity, specificity, PPV, NPV, accuracy) were calculated using bursoscopy findings as the reference. Inter-observer agreement was assessed via weighted kappa statistics.

Results
Bursoscopy detected lesions in 95% of feet, including 18 cases of DDFT dorsal fibrillation, 11 DDFT splits, 19 fibrocartilage defects, and 8 adhesions. MRI achieved the highest overall accuracy for DDFT fibrillations (95%) and splits (86%), with high inter-observer agreement (κ = 0.77–0.91). Bursography showed strong performance in detecting fibrocartilage defects (accuracy 76%) and adhesions (accuracy 67%). Ultrasonography was moderately accurate for DDFT lesions but performed poorly for adhesions (accuracy 33%) and was not used for fibrocartilage evaluation. Adhesions were underdiagnosed by all modalities. Inter-observer agreement was lowest for ultrasonography, especially for adhesions (κ = 0.08).

Limitations
Limitations include the small sample size, lack of histopathological confirmation, and the use of low-field rather than high-field MRI, which may limit sensitivity, particularly for fibrocartilage lesions. Additionally, ultrasonography is operator-dependent, and the static images used for blind review may have reduced interpretability. Adhesion detection remained a diagnostic challenge due to modality limitations and lesion characteristics.

Conclusions
Standing MRI is the most accurate modality for detecting DDFT dorsal fibrillations and splits. Bursography outperformed MRI in detecting navicular bone fibrocartilage defects. A combined approach using ultrasonography and bursography may be a viable alternative or adjunct when MRI is not accessible, particularly in clinical settings with resource constraints. All modalities showed limited sensitivity for adhesions, emphasizing the need for further refinement or complementary diagnostic strategies.

(A) Palmaroproximal–palmarodistal oblique bursography shows mild linear pooling of the contrast agent in the lateral lobe of DDFT lobe (red arrow) and focal interruption of the contrast column at the medial aspect (white arrows) of the navicular bone (NB). (B, C) T2 high resolution transverse image at the level of the proximal navicular bursa recess and the navicular bone respectively. The images show moderate distention of the proximal recess of the navicular bursa associated with thickening of the synovial membrane. There is also border effacement between the navicular bursa and the medial deep digital flexor tendon lobe (DDFT). The latter has mild dorsal fibrillation and frying (white arrow). The lateral DDFT lobe has focal hyperintense lesion in the dorsal aspect (red arrow). (D) Ultrasonography of the DDFT at the level of distal middle phalanx. The medial DDFT lobe has a smaller cross-sectional area compared to the lateral lobe and is associated with mild thickening of the dorsal aspect (red arrow). The lateral lobe has focal hyperechogenic area at the dorsal aspect (white arrow). (E) Bursoscopy showed adhesion formation with origin the DDFT (red arrow).

How did we do?

Login or Subscribe to participate in polls.

Disclaimer: The summary generated in this email was created by an AI large language model. Therefore errors may occur. Reading the article is the best way to understand the scholarly work. The figure presented here remains the property of the publisher or author and subject to the applicable copyright agreement. It is reproduced here as an educational work. If you have any questions or concerns about the work presented here, reply to this email.