Regenerative Peripheral Nerve Interface (RPNI) for Pain Control

Understanding RPNI for Pain Management

For amputees dealing with neuroma pain (NP) and phantom limb pain (PLP) there is a less invasive alternative to targeted muscle reinnervation (TMR) surgery called the Regenerative Peripheral Nerve Interface (RPNI). The early evidence suggests that this procedure can offer significant pain control but is not as robust a solution as TMR. However it is an effective option in some scenarios (for example in finger amputation or isolated single neuromas) and for those who may not be suitable for or interested in TMR surgery.

What is RPNI?

RPNI is essentially a mini-version of TMR. It involves taking small pieces of muscle tissue, usually from the lateral thigh, and wrapping them around the cut nerve ending (neuroma). This encourages the nerve fibers to connect with the muscle tissue, which then receives blood supply from the surrounding tissues. This reduces the nerve’s sensitivity and, consequently, pain.

When is RPNI Used?

While RPNI might not be as effective as TMR in reducing NP and PLP, it is particularly useful for isolated neuromas in areas with limited muscle, such as the fingertips. It can also be effective in addressing recurrent neuroma pain after TMR surgery, a phenomenon known as “unmasking.”

Procedure and Recovery

Length of Stay

Patients undergoing RPNI surgery typically go home the same day, unless the surgery is combined with osseointegration or involves a high-level amputation (e.g. through-shoulder), in which case a longer stay for pain control might be necessary.

Pain Control After Surgery

  • Pre-Surgery: Continue taking your usual pain medications.
  • Post-Surgery: You may experience an increase in phantom limb pain, which could peak 3-6 months after the procedure. Adjust medications such as pregabalin as needed.
  • Pain Management: Surgical pain is usually minimal and can be managed with simple painkillers or mild opioids for a few days.

Wound Care

  • Incisions: The primary incision will be closed with absorbable sutures that do not need removal. There will also be an incision on your thigh or forearm for the muscle graft.
  • Hygiene: You can wash and shower with running water immediately after surgery but avoid heavy use of the treated limbs for 2-3 weeks.
  • Prosthesis Use: Do not use your prosthesis until the wounds have healed and any swelling has gone down, typically around 3 weeks.

No Specific Rehabilitation Required

Unlike some other procedures, RPNI performed for pain relief does not require a specific rehabilitation program. You can gradually return to normal activities as you recover.

RPNI is a viable option for controlling neuroma pain and phantom limb pain for those seeking a less invasive solution than TMR. It allows for effective pain management with a relatively quick recovery time, helping amputees improve their quality of life. If you are experiencing NP or PLP and are interested in RPNI, contact us to find out more.