Tenosynovitis of the digital flexor tendon sheath and annular ligament constriction syndrome caused by longitudinal tears in the deep digital flexor tendon: a clinical and surgical report of 17 cases in warmblood horses.
Authors: Wilderjans H, Boussauw B, Madder K, Simon O
Journal: Equine veterinary journal
Summary
# Editorial Summary Chronic tenosynovitis of the digital flexor tendon sheath (DFTS) frequently frustrates clinical management in warmblood horses, with many cases remaining unresponsive to conventional medical and surgical approaches. Wilderjans and colleagues reviewed 25 warmblood cases presenting with chronic DFTS distension and/or annular ligament constriction syndrome (ALCS), performing tenoscopical examination to investigate longitudinal tears (LTs) in the deep digital flexor tendon (DDFT) as a potential underlying cause. Longitudinal tears were identified in 17 of the 25 horses (68%), yet standard ultrasonography alone detected only 11 cases showing relevant changes at the DDFT borders—highlighting a significant diagnostic limitation of imaging without direct visualisation. Surgical treatment combining mechanical resection of torn collagen fibres with palmar annular ligament transection yielded variable outcomes: ten horses (59%) returned to previous work soundly, four required ongoing intrasynovial medication and reduced workload, and three remained chronically lame. For practitioners managing refractory DFTS cases, this work underscores that longitudinal tears represent a substantive differential diagnosis that ultrasonography cannot reliably exclude, making tenoscopic examination essential for accurate diagnosis and effective surgical planning—particularly when palmar annular ligament transection alone has previously failed to resolve clinical signs.
Read the full abstract on PubMed
Practical Takeaways
- •Chronic digital flexor tenosynovitis and annular ligament constriction unresponsive to medical treatment or simple PAL transection should raise suspicion for longitudinal DDFT tears—tenoscopy is essential for accurate diagnosis rather than relying on ultrasound alone
- •Tenoscopic surgery combining mechanical debridement of torn fibers with PAL transection offers reasonable prognosis, with nearly 60% of horses returning to full soundness and previous work levels
- •Cases that do not respond to conservative treatment or PAL transection alone warrant referral for advanced diagnostic imaging and potential tenoscopic intervention to improve long-term outcomes
Key Findings
- •17 of 25 horses (68%) with chronic tenosynovitis and ALCS had longitudinal tears in the DDFT diagnosed by tenoscopy
- •11 of 17 affected horses (65%) showed ultrasonographic changes at the lateral or medial border of the DDFT, but ultrasonography alone cannot definitively diagnose longitudinal tears
- •Surgical treatment combining mechanical resection of torn fibrils and transection of the palmar annular ligament under tenoscopic control resulted in 10 horses (59%) returning to previous work level without ongoing lameness
- •4 horses (24%) returned to work but required ongoing intrasynovial treatment and reduced competition frequency to remain sound, while 3 horses (18%) remained lame