Persistent post-operative opioid use has been established as a possible cause of opioid use disorder [1, 2]. Therefore, the ability to offer non-opioid alternatives is of significant interest. Recently, the use of nanotechnology has been reported as a possible method to treat arthritis pain ^[3]. Here, we report the use of the newly designed NeuroCuple™ device (nCap Medical, Salt lake City, Utah) for the management of post-operative pain following a primary total knee arthroplasty (TKA) replacement. The proposed mechanism of action of the NeuroCuple™ is based on the concept that local pain is the result of inflammation, which is associated with an increase in local temperature/energy. The NeuroCuple™ contains nano-capacitances capable of absorbing local energy and is consequently able to decrease local inflammation and pain (Fig. 1).

Our patient was a male, 70-year-old, weight 107 kg, height 181 cm, who underwent a primary right total knee replacement on January 19, 2023. His medical history was remarkable for osteoarthritis of the right knee, hypertension, hyperlipidemia, diverticulosis, psoriatic arthritis, eczema, cataracts, left eye ptosis, benign prostatic hyperplasia, heart murmur, and a past fracture of the right ankle. The patient’s past surgical history included two right knee arthroscopies in 1993, anterior cruciate ligament reconstructive surgery in 1995, cataract surgery, and a tonsillectomy. Pre-operative medications included Lipitor 100 mg daily, hydrochlorothiazide 25 mg daily, potassium 10 mEq daily, apremilast 30 mg BID, and naproxen 660 mg BID that was stopped 7 days before the surgery. Before being transferred to the operating room, a right adductor canal block was performed using ultrasound and an injection of 15 mL of 0.5% ropivacaine. Surgery was performed under spinal anesthesia and propofol sedation. Following surgery, the patient’s pain was rated between 3 and 7 on the pain rating scale. Post-operative pain was managed with acetaminophen PO 1000 mg q8h, celecoxib PO 200 mg BID, and oxycodone 5–10 mg q 4 h PRN for breakthrough pain. In the hospital, the patient used a continuous passive motion machine. The patient was discharged home on post-operative day 2 (1/21) with a 1-time prescription of 44 pills of 5 mg of oxycodone to control 8/10 breakthrough pain at home for an additional 3–5 days. He was asked to continue taking celecoxib PO 200 mg BID and acetaminophen PO 1000 mg q8h. The patient’s opioid prescription was filled. At home, the patient placed a NeuroCuple™ device above the knee bandage (Fig. 2) and kept it in place from January 21 to February 6 (16 days). During this period, he did not require any opioids.

Although there is a consensus to reduce and sometime eliminate the use of opioids because of the ongoing opioid crisis and the documented associated risk of opioid use disorder in surgical patients, ^[4] most patients undergoing TKA are still prescribed a limited amount of opioids for breakthrough pain because evidence shows that the use of opioids facilitates immediate functional recovery following TKA ^[5]. Evidence supports the concept that complementary approaches, including acupuncture [6, 7], auriculotherapy ^[8], hypnosis ^[9], and transcutaneous electrical nerve stimulation ^[10] may represent an alternative to opioid use in surgical patients. However, many reviews have questioned the validity of the effectiveness of these complementary approaches because the effectiveness of these techniques is based on anecdotal reports, and randomized placebo-controlled studies are lacking [11, 12]. One report argued that acupuncture treatment is not superior to placebo ^[13]. In addition, these techniques require extensive expertise, which limits their use on a large scale. Nanotechnology has been shown to have several medical applications, including facilitating wound healing, the treatment of neurological and cardiac disorders [14, 15, 16], and the management of arthritic pain. Although evidence supporting the use of nanotechnology for pain associated with surgery is still lacking, the use of the NeuroCuple™ does not require extensive training and therefore represents a technique that can be used on a large scale and may represent an interesting alternative to the use of opioids in surgical patients undergoing skeletal-muscle procedures.

Although our data are encouraging, further research is required to confirm that the NeuroCuple™ device may represent an important and easy-to-use alternative to opioids to manage pain following surgery.

The use of nanotechnology may represent an interesting alternative to the use of opioids and may avoid the associated risk of opioid use disorder to manage pain following knee arthroplasty. The technology is non-invasive, easy-to-use, and well-tolerated.