Approximately 10% to 20% of total knee arthroplasty (TKA) patients have persistent postoperative pain. Data from a new multicenter, randomized, double-blind, placebo-controlled study trial concluded that percutaneous peripheral nerve stimulation can reduce average post-op TKA pain ≥50% and improve function.
Their work, “Randomized Placebo-Controlled Trial of 60-Day Percutaneous Peripheral Nerve Stimulation Treatment Indicates Relief of Persistent Postoperative Pain, and Improved Function After Knee Replacement,” appears in the July 2024 edition of Neuromodulation.
For the study, the 11 separate research teams randomized their post-op TKA patients to receive either active percutaneous peripheral nerve stimulation or placebo stimulation. Both patient groups received ultrasound-guided percutaneous placements of fine-wire coiled leads. The control group’s leads were “live” and the placebo group’s did not convey any electrical stimulation. Both group’s implants targeted femoral and sciatic nerves in each patient’s most postoperatively painful leg; leads were left in for eight weeks.
Co-author Yashar Eshraghi, M.D., program director of the Pain Medicine Fellowship Training Program at Ochsner Health System in New Orleans, Louisiana, told OTW, “Orthopedic surgeons may not fully appreciate that percutaneous peripheral nerve stimulation offers a novel, nonopioid treatment for managing chronic postoperative pain, particularly following procedures like TKA.”
“Unlike traditional approaches that rely heavily on opioids or more invasive interventions, peripheral nerve stimulation is a minimally invasive option that doesn’t require long-term implants or destructive techniques like radiofrequency ablation or cryoneurolysis.”
“Peripheral nerve stimulation works by engaging both peripheral and central mechanisms of pain relief, a significant departure from the more common modalities such as physical therapy or opioid therapy, which primarily target peripheral symptoms.”
Dr. Eshraghi, who is also associate professor, University of Queensland – Ochsner Clinical School of Medicine and clinical assistant professor at the Louisiana State University School of Medicine, noted, “Previous small-scale trials and case series had indicated that peripheral nerve stimulation might be effective in the immediate postoperative period, especially for acute pain management. However, these studies lacked the robust evidence needed to confirm its effectiveness in chronic pain scenarios, where pain persists months or even years after surgery.”
“This study sought to close that gap by conducting a double-blind, placebo-controlled trial aimed specifically at patients with chronic postoperative pain following TKA.”
“By focusing on patients with ongoing moderate-to-severe pain months after surgery, this research provides stronger evidence that the benefits of peripheral nerve stimulation extend beyond the acute recovery phase.”
“The placebo control, rigorous blinding, and longitudinal follow-up helped differentiate the effects of active peripheral nerve stimulation from natural healing processes, offering a clearer picture of the true efficacy of the treatment for long-term pain management.”
“The team found that a greater proportion of subjects in the peripheral nerve stimulation groups than in the placebo group responded with ≥50% pain relief from baseline by week 5-8, which was the study’s primary endpoint.”
Functionally, the research group reported that treated subjects walked a significantly greater distance at the end of the treatment period than did those in the placebo group.
Potential Downsides
“While peripheral nerve stimulation is generally considered safe and well-tolerated, there are some potential downsides to consider,” said Dr. Eshraghi to OTW. “The most commonly reported adverse events are mild to moderate and include skin irritation due to the bandaging used at the lead insertion sites, as well as occasional discomfort from wearing the external components of the device . These side effects are typically manageable and transient.”
“A less frequent but notable downside is the risk of lead fractures during removal. Although rare, when the fine-wire lead used in peripheral nerve stimulation fractures during extraction, it may leave behind a small fragment in the patient’s body.”
“Fortunately, these remnants are considered safe and do not pose long-term risks, including during future MRI scans, as they are MRI-conditional. Recent technological advancements, including the introduction of strengthened leads, have significantly reduced the occurrence of lead fractures, further improving the safety profile of peripheral nerve stimulation.”
An Option Too Often Overlooked
“This is study provides a great option for patients besides continuing to watch and wait for years for patients to recover from their persistent post replacement knee pain,” stated co-author David Dickerson, M.D., an assistant professor in the Department of Anesthesia and Critical Care, and director of the Acute Pain Service at The University of Chicago Pritzker School of Medicine in Illinois.
“Watching and waiting for persistent pain to resolve after 12 months post replacement doesn’t commonly lead to further patient improvement. Hopefully, a study like this will raise awareness and generate practice changes that enable patients with persistent knee pain after replacement to be evaluated by pain medicine specialists in a timely fashion for definitive treatment.”
“Beyond TKA, peripheral nerve stimulation can be applied to a range of other orthopedic procedures, including hip and shoulder arthroplasty, as well as other surgeries that often result in chronic postoperative pain,” commented Dr. Eshraghi to OTW.
“The adaptability of peripheral nerve stimulation to target specific peripheral nerves related to various joints makes it a valuable and underutilized tool in orthopedic pain management. By not only alleviating pain but also enhancing functional recovery, peripheral nerve stimulation offers benefits that extend beyond mere analgesia, which could significantly impact patient outcomes across a wide spectrum of orthopedic surgeries.”
