EP038 Comparative assessment of needle tip positioning for genicular nerve block using ultrasound guidance versus fluoroscopic landmarks in chronic knee osteoarthritis: an observational study

<h3>Background and Aims</h3> Genicular nerve block (GNB) is performed using both fluoroscopy (FL) and ultrasound (USG) guided techniques. These techniques identify the targets using specific approaches. Our primary aim was to measure the difference in needle position between USG and FL guided techniques <h3>Methods</h3> We had recruited 48 patients. GNB was performed by experienced anaesthesiologist using echogenic needle under USG guidance. The conventional USG landmarks were the targets in superomedial (SM), superolateral (SL), and Inferomedial (IM) GNB. After injection, all needles were kept in situ. Then, both anterior-posterior (AP) and lateral fluoroscopic images of the knee were taken. Post-block pain scores were assessed at one hour, six hours, 24 hours, and one month. Later, the needles from fluoroscopic image were removed using software. The edited image was shown to anaesthesiologist and asked to mark the target for FL guided GNB. Both the original and edited images were superimposed and the distance between two points were measured. The first point was USG guided needle position and second point was the target point for fluoroscopy as marked. This was measured in SM, SL, and IM needle position. The second point was considered as acceptable if it was within 5 mm radius of the first point <h3>Results</h3> The average distance between two points in AP view was 3.9±2.6, 4.4±3.0 and 3.8±2.6 in SM, SL, and IM respectively. In the lateral view it was 6.2±3.0, 6.8±3.5 and 6.3±2.9 in SM, SL, and IM respectively. Mean NRS scores at baseline, 1 hour, 6 hours, 24 hours, and 1-month were noted. Though only eight patients had acceptable needle position in both images, all 48 patients had a significant pain relief <h3>Conclusions</h3> Average distance between the between the needle tip of USG and FL guided GNB was 4.0±0.3 mm and 6.4±0.3 mm in AP and lateral images respectively