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

BACKGROUND: the protocol for mobilization of the fetlock region prior to acquiring a contrast tenogram radiograph is not clearly defined. OBJECTIVE: to determine if walking exercise improves identification of DFTS pathology on contrast tenography. METHODS: Prospective cohort study. Nineteen horses that underwent contrast tenography and subsequent surgical tenoscopy were included. A tenogram protocol was developed to enable comparison of diagnostic accuracy after increasing mobilization of the affected limb post-injection. Following contrast injection three tenogram radiographs were taken, (1) immediately post-injection, (2) after manual fetlock flexion, (3) after walking. Tenoscopic findings were compared with radiological diagnosis. RESULTS: The detection rate for both MF and DDFT tears improved with increasing limb mobilization (static<post-flexion<post-walking), increasing from 37% to 47% to 68% for detecting MF tears for each condition, and 26% to 47% to 79% for DDFT tear detection. Sensitivity and specificity had an overall upward trend for detecting MF and DDFT tears. For detection of DDFT tears sensitivity increased with increasing limb mobilization from 22%, to 50% post flexion; and to 71% post walking with a consistent 100% specificity throughout. For detection of MF tears sensitivity and specificity went from 67% and 50%; to 50% and 58% post-flexion; increasing to 60% and 71% post-walking. In five horses (5/19, 26%) radiographic diagnosis changed from incorrect prior to walking, to correct following walking exercise. CONCLUSIONS: Walking exercise prior to contrast tenogram acquisition improves diagnostic accuracy for detecting MF and DDFT tears. Walking exercise should be undertaken as standard for contrast tenograms for accurate diagnosis.