Freehand magnetic needle guidance technology for intra-articular cervical injection in horses

The use of ultrasound-guided injections is a widely known and well-established procedure in equine medicine not only for intra-articular procedures but also for treating injuries affecting soft tissues. The aim of this study was to compare the conventional ultrasound-guided technique (CUGT) with a modified ultrasound-guided magnetic navigation technique (MUGT) in the articular process joints spaces of the cervical vertebrae. The aforementioned techniques were compared by measuring the degree of difficulty, the time employed and the success of the procedure (injecting blue methylene into the articular process joints spaces of cadavers to allow us to know whether the procedure was successful). Neck specimens from 11 cadavers were used to conduct this study. To compare the two different techniques, the articular process joints spaces of 11 specimens were injected bilaterally using ultrasound guidance, using one technique on each side. One millilitre of methylene blue was injected into the C2-C3, C3-C4, C4-C5 and C5-C6 articular process joints; then, these joints were dissected to verify the success rate of the injections. The results were similar regarding the success rate of the procedure; however, there were differences in the time employed (25.0 s median runtime for MUGT vs. 32.1 s median runtime for CUGT) and the degree of difficulty (1.3 attempts on average for MUGT vs. 2.4 attempts on average for CUGT). According to the results of this study, MUGT involved less difficulty and slightly less time employed to inject the cervical articular processes joints than CUGT; however, further studies in live horses are needed to assess the efficiency of this method, and studies in other joints or soft tissues are needed to validate the method. This new technique could also improve other equine ultrasound-guided procedures, such as nerve blocks, ultrasound-guided tendon/joints treatments or other articular injections.