60-Day Peripheral Nerve Stimulation Reduces Persistent Pain and Improves Function After Total Knee Arthroplasty: Results From a Randomized Controlled Trial

Background and/or Objectives: Total knee arthroplasty (TKA) is effective in most cases, but 10-20% of patients experience persistent postoperative pain and/or poor function. This study evaluated 60-day peripheral nerve stimulation (PNS) for pain relief and functional improvement after TKA.

Design: This Institutional Review Board (IRB)-approved randomized controlled trial enrolled patients with persistent postoperative pain after TKA. Key exclusion criteria included high opioid use (≥90 mg/day morphine equivalent dose) and revision TKA. Participants received an FDA-cleared 60-day PNS device and were randomized (1:1) to active PNS or placebo (sham) stimulation.

Setting : 11 United States clinical sites.

Participants : 52 participants were randomized (average 4.1 years post-TKA), and 41 (PNS: 20, Placebo: 21) completed primary endpoint assessments (weeks 5-8).

Interventions: Both groups received percutaneous leads targeting the femoral and sciatic nerves for 8 weeks. The PNS group received active stimulation; the Placebo group received sham stimulation (device appeared to work but no current delivered).

Main Outcome Measures: The primary outcome was the proportion of participants achieving ≥50% pain relief (responders; 0-10 numerical rating scale) during weeks 5-8. Secondary outcomes at end of treatment included the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and six-minute walk test (6MWT). All improvements are reported relative to baseline.

Results: The PNS group had significantly more responders (PNS=60% vs. Placebo=24%; p=0.03) and a greater reduction in pain scores (median improvement: PNS=3.9 vs. Placebo=1.0; p=0.004) compared to the placebo group. Total WOMAC scores were significantly improved (median improvement: PNS=4.1 vs. Placebo=1.9; p=0.03), as were the pain, stiffness, and function subscales. Walking ability also improved (6MWT; PNS=47% vs. Placebo=-9%; p=0.048). No study-related serious or unanticipated adverse events occurred (most common adverse event: skin irritation).

Conclusions: 60-day PNS significantly reduced pain and improved function in TKA patients, supporting its efficacy as a non-opioid option for persistent postoperative pain.