Correlation and Prognostic Value of Abnormalities on MRI and Navicular Bursoscopy in Horses with Foot Lameness

Introduction: Hyperintense masses dorsal to the suprasesamoidean deep digital flexor tendon are often identified on MRI of horses with foot lameness. Endoscopic surgery of the navicular bursa often identifies collagenous clumps of tissue. We hypothesized that these were the masses on MRI, and prognosis following surgery was limited by any tendon lesion.

Materials and Methods: A retrospective study of horses following MRI and navicular bursoscopy. Size of any mass and abnormalities of the DDFT on MRI and surgery were subjectively graded. Correlation of MRI and surgical findings was compared by Spearman Rank non-parametric correlation.

Results: Forty horses that had 1 year of follow-up were included. There was good correlation of the size of the mass (R = 0.751). However, correlation of DDFT lesions was not strong (R = 0.48). The prognosis was guarded, with 12 horses (30%) returning to previous level of exercise. There was no effect on prognosis and only 3/16 (19%) horses with large synovial masses but minimal tendon lesions on MRI returned to exercise.

Discussion/Conclusion: Hyperintense masses adjacent to the dorsal border of the deep digital flexor tendon are predictive of masses of collagenous tissue. Our hypothesis of a good prognosis for a horse with a large mass but no visible tendon disease on MRI was not confirmed. There was poor correlation of MRI and surgical findings concerning tendon lesions, due to horses with minimal tendon lesion on MRI, but surface erosion of the deep digital flexor tendon at bursoscopy.

Acknowledgement: There was no proprietary interest or funding for this project.