A Randomized Controlled Pilot Study Using Ultrasound-Guided Percutaneous Cryoneurolysis of the Infrapatellar Branch of the Saphenous Nerve for Analgesia Following Total Knee Arthroplasty.

introductionTotal knee arthroplasty (TKA) is frequently associated with severe, prolonged postsurgical pain, and therefore local anesthetic-based peripheral nerve blocks are commonly used for postoperative analgesia. Cryoneurolysis involves the use of freezing temperatures to provide a reversible sensory (and motor) block with a duration measured in weeks and months, more commensurate with the typical period of post-TKA pain. We therefore conducted a randomized controlled pilot study to evaluate the use of this modality for the treatment of pain following TKA to (1) determine the feasibility of and optimize the study protocol for a subsequent definitive clinical trial; and (2) estimate analgesia and opioid reduction within the first 3 postoperative weeks.

methodsA convenience sample of 16 patients undergoing primary TKA with a single-injection and/or continuous adductor canal nerve block were randomized to receive either active cryoneurolysis or a sham procedure targeting the infrapatellar branch of the saphenous nerve, in a participant-masked fashion. This was a pilot study with a relatively small number of participants, and therefore resulting data were not analyzed statistically.

resultsCompared with participants receiving sham, the active treatment group reported slightly lower average and worst pain scores as well as opioid consumption and sleep disturbances due to pain at a majority of postoperative time points between postoperative days (POD) 4-21.

conclusionsPreoperative ultrasound-guided cryoneurolysis of the infrapatellar branch of the saphenous nerve is feasible and may provide analgesic benefits for multiple weeks following TKA. A definitive randomized controlled trial appears warranted.