Ultrasound guidance aids in determining the success of equine temporomandibular joint arthrocentesis.

Background: The equine temporomandibular joint (TMJ) is divided into two non-communicating joint (discotemporal DTJ and discomandibular DMJ) compartments. Ultrasound has been extensively used as a diagnostic tool in the horse, but previous work has reported that ultrasound-guidance did not improve the success rate of TMJ arthrocentesis. However, this research focused only on the larger, easily accessed, DTJ compartment. However, most of the osseous pathology of the equine TMJ has been reported to be in the smaller DMJ. Objective: To determine whether using ultrasound-guidance would reduce the number of attempts to successfully perform arthrocentesis of the equine TMJ, specifically the DMJ. Study design: Experimental study using cadaver animals. Methods: The TMJ regions of seven thawed cadaver heads were clipped and cleansed. Arthrocentesis of the left DTJ and DMJ was attempted before repeating the attempts using ultrasound guidance. The number of attempts required to perform successful arthrocentesis of each joint compartment was documented before the second operator performed the same task. The same procedures were then performed on the opposite side of the head. Results: As operators gained experience, their success rate climbed. Statistically, none of the other documented outcome variables significantly affected the number of attempts to obtain successful arthrocentesis. Despite that, ultrasound-guidance allowed immediate unequivocal evidence of successful arthrocentesis into the targeted joint compartment. Main limitations: Low number of normal cadaver horse heads and a lack of randomization of attempt techniques. Conclusions: This study shows that ultrasound-guidance did not reduce the number of attempts required for successful DTJ, or DMJ arthrocentesis. However, it did allow for the immediate unequivocal evidence of successful arthrocentesis into the targeted joint compartment.