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

Abstract

Introduction Total 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. Methods A 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. Results Compared 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. Conclusions Preoperative 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.

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“…Cryoprobes for nerve analgesia range from 14G to 24G in diameter and use carbon dioxide or nitrous oxide for ice ball formation, unlike cryoequipment used for tumor ablation that uses argon gas to achieve cooler temperatures and more cellular damage using the Joule-Thomson effect. 22 The available generators have builtin nerve stimulators to perform a test for assessing sensory and motor responses aimed at achieving proper localization of the target neural structure before cryoanalgesia. 22 After each freezing cycle, a 1-to 3-minute active thaw and a 1-minute passive thaw is used.…”

“…22 The available generators have builtin nerve stimulators to perform a test for assessing sensory and motor responses aimed at achieving proper localization of the target neural structure before cryoanalgesia. 22 After each freezing cycle, a 1-to 3-minute active thaw and a 1-minute passive thaw is used. This technology allows for reversible destruction of nerves, also known as Wallerian degeneration, that prevents nerve signaling and potentially alleviates pain and motor dysfunction in a number of medical conditions.…”

“…This technology allows for reversible destruction of nerves, also known as Wallerian degeneration, that prevents nerve signaling and potentially alleviates pain and motor dysfunction in a number of medical conditions. 22 Due to the cooling effect, cryoneurolysis is generally less painful than RFA in most scenarios. 24,25 Thermal protective methods may be applied to reduce the damage of surrounding neurovascular structures, namely the skin, particularly when uninsulated probes are used.…”

“…Thus this option has proven to be an excellent and safe therapy to decrease pain and improve function in these patients. 1,22,23 The principle of genicular nerve ablation (also referred to as rhizotomy, neurotomy, or neurolysis) is the same as other sensory nerve ablation procedures: using thermal energy to obliterate the peripheral nervous tissue, destroying their cellular membranes and inducing necrosis, coagulation, or both while preserving adjacent vital structures and causing minimal adjacent cellular damage. 24 The most used ablation modality is radiofrequency (RF) energy that has been well described in the clinical and basic science literature as an effective and predictable mode for neurolysis.…”

“…Thus this option has proven to be an excellent and safe therapy to decrease pain and improve function in these patients. 1 22 23…”