EXPRESS: Development of an ultrasound-guided pericapsular knee desensitization technique in cats: an anatomical...

ObjectivesTo develop an ultrasound-guided pericapsular knee desensitization (PKD) technique targeting the medial (MAN), lateral (LAN) and posterior (PAN) articular branches of the saphenous, common fibular and tibial nerves, and to evaluate its accuracy in domestic feline cadavers.MethodsIn Phase I, six pelvic limbs from three cadavers underwent ultrasonographic evaluation and gross dissection to describe the course of the MAN, LAN and PAN and identify anatomical and sonographic landmarks for PKD. In Phase II, bilateral PKD was performed in eight cadavers (16 limbs) using 0.1 ml (low-volume, LV) or 0.2 ml (high-volume, HV) of dye per nerve, with volumes randomly assigned between limbs. MAN and PAN injections were performed under ultrasound guidance through a single medial percutaneous approach, whereas LAN injections were landmark-guided. Dissection was used to assess dye distribution around target nerves, the joint capsule and parent nerves.ResultsThe MAN was consistently located within the distal subsartorial canal alongside the descending genicular vessels, the PAN coursed adjacent to the popliteal vessels, and the LAN ran superficially near the fibular head and lateral head of the gastrocnemius muscle. Overall success was 23/24 injections (95.8%; 95% CI 78.9-99.9%) in the LV group and 21/24 (87.5%; 95% CI 67.6-97.3%) in the HV group. Both volumes stained the MAN, LAN and PAN trajectories and the medial, caudal and lateral surfaces of the knee joint capsule without intracapsular injection.Conclusions and relevanceUltrasound-guided PKD is feasible in domestic feline cadavers, and small injection volumes (0.1-0.2 ml per nerve) reliably reach pericapsular compartments containing the principal articular branches while largely sparing major motor nerves. These findings provide an anatomical and technical basis for future clinical evaluation of PKD for perioperative and chronic knee pain management in cats.