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

The study aimed to ascertain the accuracy of ultrasound-guided intra-articular injections on the cervical facet joints of horses, as well as to identify any factors that might impact this accuracy. This technique is well established in human medicine, but there has been little research regarding its use in equine medicine.

Research Methodology

• A total of sixty injections were carried out on the facet joints of horses. The horses used were not specifically for this study, but were horses that had been euthanized due to reasons unrelated to orthopaedic conditions.
• The facet joints targeted were those located between the 2nd and 7th cervical vertebrae (C2-C7).
• For clarity and ease of identifying the accuracy of the injections, they were performed using blue dye.
• After the injections, the respective facet joints were dissected to verify where exactly the dye (and therefore the injections) had landed.

Research Findings

• Post-dissection, it was observed that 72% of the injections had accurately reached the intra-articular space.
• 17% of the injections turned out to be intracapsular, meaning the injection site was within the joint capsule but not actually within the joint space itself.
• Interestingly, almost all the injections (98%) were within 1 mm of the joint capsule, indicating a high degree of accuracy overall.
• The study also found a remarkable correlation between the accuracy of the injections and the increase in experience of the person performing the injection (P < 0.01).
• The other factors evaluated in the study did not show significant effect on the injection accuracy.

Conclusions

• While the results of the study cannot be directly applied to live horses due to the difference in tissue conditions between live horses and cadavers, the study still indicates that ultrasound-guided intra-articular injections could potentially be utilized effectively in equine medicine, both for diagnostic and therapeutic purposes.
• The researchers also concluded that it is advisable for practitioners to first practice these injections on cadaver specimens before applying the technique on live horses to increase accuracy and minimize harm.