Diffusion of Radiodense Contrast Medium Following Perineural Injection of the Deep Branch of the Lateral Plantar Nerve Using Two Different Techniques in Horses: an In Vivo Study.

This research examines the way a type of medical contrast fluid spreads when injected into a specific nerve in a horse’s foot, using two different methods. The study found that while the spread of the fluid was similar for both methods after 15 minutes, the method where the horse was bearing weight on the foot led to a greater spread of fluid after 30 minutes.

Study Methodology

• The study involved eight horses. Each horse received injections of a radiopaque contrast medium (a type of fluid that can be seen on x-rays) into the deep branch lateral plantar nerves in their right and left feet.
• The injections were carried out using two techniques – a weight-bearing method where the horse stood on the foot throughout, and a flexed technique which had the horse’s foot lifted off the ground.
• Radiographic (x-ray) observations of the spread of the contrast medium were made at 5, 15, and 30 minutes after the injection. The spread was assessed in both the proximal (closer to the horse’s body) and distal (further from the horse’s body) directions. Assessments were carried out by two independent analysts who were not aware of the injection methods used.
• Statistical analysis was conducted to assess the impact of the time after the injection and the technique used on the spread of the contrast medium.

Study Results

• After 15 minutes (T15), there was no significant difference in the spread of the contrast medium between the weight-bearing and flexed techniques. However, after 30 minutes (T30), the weight-bearing technique resulted in a significantly larger spread of the medium in the proximal direction.
• In one instance in the weight-bearing group, the contrast medium was detected in the tarsal sheath, a protective layer that surrounds some of the tendons in a horse’s foot.
• No evidence of the contrast medium was found in the horse’s tarsometatarsal joint – the main joint in a horse’s foot – irrespective of the injection technique used.

Study Conclusions

• In conclusion, the results of this study showed that the spread of contrast medium in the deep branch lateral plantar nerve in a horse’s foot was comparable between the weight-bearing and flexed techniques, 15 minutes after the injection.
• However, after 30 minutes, a statistically significant increase in the spread of the contrast medium was recorded for the weight-bearing technique, particularly in the proximal direction.