Saphenous and Sciatic Nerve Blockade with and without Obturator Nerve Block for Tibial Plateau Levelling Osteotomy Surgery in Dogs: A Randomized Controlled Trial

Simple Summary Locoregional anaesthesia plays a fundamental role in the correct management of surgical interventions. Veterinary ultrasound-guided techniques are in continuous evolution to obtain adequate analgesia with minimal motor impact. We hypothesized that the block of the obturator nerve in the inguinal compartment, combined with the block of the saphenous and the sciatic nerves, without the block of the femoral nerve, could produce analgesia with less motor function impairment for tibial-plateau-levelling-osteotomy (TPLO) surgery. Having easily identified a window during the anatomical study that included an inguinal approach, we could correctly perform this new ultrasound-guided obturator-nerve-block technique. Patients that received three blocks with ropivacaine had statistically significantly less need for rescue analgesia during surgery than those that received saline solution at the level of the obturator nerve. In the group that did not receive ropivacaine for the obturator nerve block, nociception occurred in almost all patients at the time of incision of the joint capsule, showing the obturator nerve role in the innervation of the knee joint. The use of this new technique in association with the block of the sciatic and saphenous nerves represents an improvement in locoregional techniques in knee surgery, as the patient not only has a reduction in intraoperative nociception but also has better postoperative mobility, resulting from the fact that the femoral nerve, which is responsible for the innervation of the quadriceps muscles, was not blocked.Abstract The objective of our study was to compare the efficacy of sciatic and saphenous ultrasound nerve blocks with and without US-guided obturator nerve block in dogs undergoing tibial-plateau-levelling-osteotomy (TPLO) surgery. This study was developed in two phases: identification of an ultrasound window in the inguinal region for obturator nerve block and utilization of it in dogs undergoing TPLO. Dogs were assigned randomly to one of two groups: one received the three blocks with 0.5% ropivacaine (ON group) and the second one (NoON group) with NaCl instead of ropivacaine for the obturator block. In phase 1, the obturator nerve was visible between the pectineus and the abductor muscles and was approached using an in-plane technique. It was possible to use the ultrasound window for phase two. The number of dogs that received at least one bolus of intraoperative rescue analgesia in the NoON group (12/15 dogs) was significantly higher (p = 0.003) in comparison with the ON group (4/15). An ultrasound window to block the obturator nerve in the inguinal compartment with an in-plane technique was found. The use of this approach could produce adequate analgesia with less motor function impairment in dogs for TPLO surgery.