Development of an ultrasound-guided proximo-medial approach for injection of the carpal flexor tendon sheath in horses and comparison with the conventional proximo-lateral ´blind` technique.

The research article explores a new ultrasound-guided approach for injecting the carpal flexor tendon sheath in horses and compares its effectiveness with an existing ‘blind’ approach. The study demonstrated that the new technique was more accurate and completely successful.

Study Design and Methods

• The researchers designed a prospective case-control study aimed at implementing and testing a new ultrasound-guided proximo-medial approach for injecting the carpal flexor tendon sheath in horses.
• This new technique was initially developed on ten cadaveric horse limbs using an undiluted ionic iodinated contrast medium. This helped the researchers to identify landmarks and establish an access point for injection.
• After developing the technique, it was validated on ten live horses. The efficacy of this new method was then compared with the conventional proximo-lateral ‘blind’ technique commonly used for these injections.

Comparison of Techniques and Findings

• Several factors were evaluated for each injection, including successful injection (contrast within the carpal canal), number of attempts made, and whether a structure other than the carpal sheath was penetrated during the injection.
• The conventional blind technique had an accuracy rate of 70%, with inadvertent injections into other structures. Failed or misplaced injections often resulted in contrast medium entering the dorso-palmar pouch of the radiocarpal joint, surrounding soft tissue of the carpal canal, or even intravenous injection.
• On the other hand, the new ultrasound-guided approach demonstrated a 100% accuracy rate for intrasynovial administration of the contrast medium.

Conclusions

• The study concluded that the ultrasound-guided proximo-medial approach for injecting the carpal flexor tendon sheath in horses is more accurate and technically straightforward than the conventional method.
• Due to its high success rate and greater accuracy, the study recommends the use of this method, particularly in cases where the horses do not show evident effusion.