Accuracy of ultrasound-guided intra-articular injection of cervical facet joints in horses: a cadaveric study.

REASONS FOR PERFORMING STUDY: Intra-articular facet joint injection is an established diagnostic procedure in human medicine but there are no reports on its reliability in equine practice.

OBJECTIVES: To investigate the accuracy of ultrasound-guided intra-articular injections of the cervical facet joints and to estimate factors influencing the accuracy.

METHODS: Sixty injections with blue dye were performed on the facet joints between 2nd and 7th cervical vertebra (C2-C7) on horses subjected to euthanasia for nonorthopaedic reasons. The facet joints were subsequently dissected to verify accuracy of deposition.

RESULTS: Seventy-two percent of the injections were found to be intra-articular, 17% were intracapsular and a total of 98% were within 1 mm of the joint capsule. There was a marked effect of gained experience (P < 0.01), but not of other factors tested.

CONCLUSIONS AND POTENTIAL RELEVANCE: The results of the present study do not translate directly to injections performed in live horses, but they indicate that the method can be applied as a diagnostic as well as therapeutic procedure in C2 to C7 and that is advisable to practise injections on cadaver specimens before applying the technique.