Walking prior to contrast tenogram radiograph acquisition improves radiological identification of equine digital flexor tendon sheath pathology.

Walking before taking contrast tenogram X-rays helps veterinarians better identify injuries in the digital flexor tendon sheath of horses. This study investigated whether increasing movement of a horse’s limb before imaging improves the detection of tendon sheath injuries.

Background and Objective

• Contrast tenography is an imaging technique used to diagnose lesions in the digital flexor tendon sheath (DFTS) in horses.
• The best protocol to prepare the limb, especially how much to mobilize or move the fetlock region before taking radiographs, was not clearly established.
• The study aimed to determine if walking the horse after contrast injection improves the ability of tenogram radiographs to detect tendon sheath pathology, specifically tears in the manica flexoria (MF) and deep digital flexor tendon (DDFT).

Methods

• Design: Prospective cohort study including 19 horses confirmed to have DFTS pathology through surgical tenoscopy (gold standard).
• Three tenogram radiographs were taken per horse after contrast injection:
  • Radiograph 1: Immediately post-injection (static limb)
  • Radiograph 2: After manual flexion of the fetlock joint
  • Radiograph 3: After the horse was walked (mobilized limb)
• These images were compared to the surgical findings to measure diagnostic accuracy.

Results

• Detection rates for MF and DDFT tears increased progressively with greater limb mobilization:
  • MF tear detection improved from 37% (static), 47% (post-flexion), to 68% (post-walking).
  • DDFT tear detection improved from 26% (static), 47% (post-flexion), to 79% (post-walking).
• Sensitivity and specificity trends also improved with mobilization:
  • DDFT tear detection sensitivity rose from 22% (static), to 50% (post-flexion), and 71% (post-walking), with specificity remaining at 100% throughout.
  • MF tear detection showed sensitivity/specificity pairs of 67%/50% (static), 50%/58% (post-flexion), and 60%/71% (post-walking).
• In 5 out of 19 horses (26%), the diagnosis from radiographs changed from incorrect prior to walking to correct after walking.

Conclusions and Clinical Implications

• Walking the horse after contrast injection before taking tenogram radiographs significantly improves the ability to detect tears in the MF and DDFT within the digital flexor tendon sheath.
• Increasing limb mobilization, culminating in walking, helps distribute the contrast agent more effectively or changes the conformation of the sheath and tendons in a way that reveals pathology better.
• Based on these results, incorporating walking exercise as a standard part of the contrast tenography protocol is recommended for more accurate diagnosis.
• This protocol adjustment can lead to earlier and more reliable identification of tendon sheath injuries, guiding better treatment decisions and potentially improving outcomes for affected horses.