Synovial masses within the navicular bursa

Presence and size of synovial masses within the navicular bursa correlate well between magnetic resonance imaging and bursoscopy and have a guarded prognosis
Equine Vet J. 2023 Dec 22. doi: 10.1111/evj.14040. Online ahead of print.
Authors
Maria Elisabetta Giorio 1 , Robyn J Graham 2 , Dagmar Berner 1 , Henry D O’Neill 3 , Bruce M Bladon 3
Affiliations

1 Equine Referral Hospital, Department of Clinical Science and Services, Royal Veterinary College, University of London, Hatfield, UK.
2 Equine Hospital, Royal (Dick) School of Veterinary Studies, University of Edinburgh, Midlothian, UK.
3 Donnington Grove Veterinary Group, Berkshire, UK.

PMID: 38131123
DOI: 10.1111/evj.14040

Abstract
in English, German

Background: Focal hyperintense lesions within the navicular bursa emanating from the dorsal border of the deep digital flexor tendon (DDFT) can be recognised on T1-weighted magnetic resonance images (MRI) and have been attributed to lameness in horses. Removal of these lesions, also referred to as synovial masses, by navicular bursoscopy is currently recommended.

Objectives: To investigate the correlation between MRI and navicular bursoscopic findings. It is hypothesised that the prognosis following surgery is proportional to the size of the DDFT lesion.

Study design: Retrospective analysis of clinical records.

Methods: Horses undergoing standing low-field MRI and navicular bursoscopy with >1 year follow-up were included. A grading system was developed to classify the size of synovial mass(es) and lesion(s) of the DDFT on MRI and at surgery. Generalised estimating equations were used to evaluate the association between MRI findings and surgery and between outcome and severity of the tendon injury.

Results: Fifty-nine horses presenting over a 15-year period (2006-2021) fulfilled inclusion criteria. Ninety navicular bursae were examined both on MRI and endoscopically. There was strong correlation between the size of synovial masses and tendon lesions on MRI and bursoscopy (p < 0.001, OR: 25.61, 95% CI 8.71-75.29 and p < 0.001, OR: 7.34, 95% CI 2.70-19.92, respectively). Size of tendon lesion and synovial mass had no impact on prognosis (p = 0.3, OR: 1, 95% CI 1-1 and p = 0.1, OR: 1, 95% CI 1-1, respectively), which was guarded (30.5% return to previous level of exercise). Main limitations: Performance data for conservatively treated horses with MRI-detected synovial masses was not considered, nor was the effect of navicular bursal effusion. Horses were not randomly assigned to treatment protocols. Conclusion: There is good correlation between MRI and bursoscopic findings of DDFT lesions and synovial masses within the navicular bursa, with no false positives. Size of the synovial masses and DDFT lesions does not influence prognosis following navicular bursoscopy.