Persistent pain after knee replacement needs a diagnosis
A knee replacement can improve arthritis pain, but persistent or newly recurring pain deserves a thoughtful evaluation. The source may be related to the implant or surrounding tissues, infection, a fracture, stiffness, nerve sensitivity, another medical condition, or pain referred from elsewhere. These causes require different care.
Before considering a pain-modulating procedure, Dr. Morton reviews your symptoms, prior treatment, examination, imaging, and relevant laboratory testing. If infection, loosening, instability, or another correctable problem is suspected, that issue needs to be addressed first. The revision joint clinic provides a systematic workup for painful or failing hip and knee replacements.
What is peripheral nerve stimulation?
Peripheral nerve stimulation uses electrical pulses delivered through a small electrode placed near one or more nerves that carry sensation from the knee. The goal is to change how pain signals are processed. The electrode does not replace the knee implant, and PNS does not correct infection, component loosening, fracture, or instability.
PNS is different from a nerve block, which temporarily numbs a nerve with medication, and from radiofrequency ablation, which uses heat to interrupt selected nerve signals. It is also different from a spinal cord stimulator because the target is a peripheral nerve near the painful area. Devices and treatment protocols vary; the exact system and plan should be explained before any procedure.
Who might be considered?
PNS may be discussed for some people whose knee pain remains function-limiting after replacement, after an appropriate evaluation has not found a problem that should be treated another way. The pain pattern, health history, prior treatments, goals, ability to manage the device, and willingness to attend follow-up all matter.
There is no single test that makes someone a candidate. A consultation is needed to determine whether a nerve-based treatment is reasonable, whether another treatment is a better fit, and what uncertainties apply to your situation.
What to expect from evaluation and treatment
At a consultation, bring your operative report or implant information if available, recent X-rays or other imaging, a list of medications, and a short timeline of your pain and prior treatments. If your knee replacement was performed elsewhere, the team can advise what records are useful and how to arrange an evaluation.
- Review the cause of pain. Your symptoms, examination, imaging, and any necessary tests guide the next step.
- Discuss options. The plan may include rehabilitation, medication, a targeted injection or nerve procedure, revision surgery for a correctable implant problem, or coordinated pain care.
- Confirm the specific PNS plan if appropriate. Lead placement, device type, treatment period, activity guidance, and follow-up vary by system. These details and the expected costs or coverage process should be reviewed before proceeding.
Do not stop prescribed medication or change your recovery plan based on this page. Contact your treating team for advice tailored to your knee.
What does the research show?
Evidence is encouraging but still developing. In a small randomized, double-blind study of 41 people with persistent pain after total knee replacement, 12 of 20 participants who received 60-day percutaneous PNS (60%) and 5 of 21 who received sham stimulation (24%) reported at least a 50% reduction in average pain during weeks five through eight. The study supports PNS as a possible option for some patients; its small size and limited follow-up mean it cannot predict an individual patient's result or establish that every device and protocol works the same way.
A 2026 multispecialty evidence guideline includes refractory chronic postsurgical knee pain among conditions for which PNS may be offered. A recommendation does not mean every patient is a candidate or that treatment is guaranteed to work. Your clinician should review the evidence and alternatives in the context of your evaluation.
Sources: Randomized placebo-controlled trial of 60-day PNS after knee replacement (2024); Multispecialty evidence-based PNS guideline (2026).
Risks, alternatives, and realistic expectations
Potential risks depend on the device and placement technique. They can include soreness or skin irritation, bleeding, infection, lead movement, uncomfortable stimulation, and rarely nerve injury. The treating clinician should review device-specific risks, precautions, and what to do if a lead or dressing changes before treatment begins.
Other options may include continued physical therapy, activity and medication adjustments, targeted injections or other nerve procedures, multidisciplinary pain care, or revision surgery when a correctable implant problem is identified. PNS is not a substitute for evaluation of new or worsening pain. No treatment can promise a particular level or duration of pain relief.
When to seek urgent assessment
Contact your orthopedic team promptly for fever, drainage from the incision, sudden swelling, rapidly worsening pain, a new inability to bear weight, or other concerning changes. New chest pain, shortness of breath, or significant calf swelling after surgery needs urgent medical attention.
Medically reviewed by Paul N. Morton, MD, FAAOS, FAAHKS — board-certified orthopedic surgeon, fellowship-trained in adult hip & knee reconstruction and orthopedic trauma. Last reviewed: .
This page is for education only and isn’t a substitute for an exam and personalized advice — schedule a consultation to discuss your situation.