Peripheral Neuromodulation for Chronic Knee pain following surgery

Novel approach for peripheral subcutaneous field stimulation for the treatment of severe, chronic knee joint pain after total knee arthroplasty.

www.neuromodulationjournal.com © 2009 International Neuromodulation Society Neuromodulation 2010; 13: 131–136

William Porter McRoberts, MD, Martin Roche, MD

Objective: The objective of this study is to present a novel approach for the treatment of severe, chronic knee joint pain following total knee arthroplasty utilizing peripheral subcutaneous field stimulation and discuss the role of this treatment modality in patients with symptoms that are refractory to conventional pharmacologic, surgical, and physical therapies.

Materials and Methods: Presented are two case reports of patients with chronic intractable knee pain where peripheral nerve stimulation via a permanent neurostimulating implant was introduced successfully. Both patients presented with persistent knee pain, for greater than one year, after having had total knee arthroplasty. The patients’ symptoms failed to be alleviated by a variety of interventions including non-steroidal anti-inflammatory drugs (NSAIDS), oral antidepressants, membrane stabilizers, opioids, physical therapy, surgical revisions, manipulation under anesthesia, local anesthetic patches, and transcutaneous electrical nerve stimulation. In each case, direct stimulation of the knee was achieved utilizing a peripheral nerve stimulator via a periarticular approach.

Results: Neuromodulation daily has produced both significant pain relief and functional improvement. Significant decreases in pain visual analog scale (VAS) scores and improvement in functional capacity were observed during the stimulation trial and during the follow-up after permanent implantation. The mean VAS score changed dramatically.

Conclusions: Introduction of a peripheral subcutaneous field stimulation directly to the painful knee area is a novel and simple procedure that was extremely effective for the relief of pain and may provide a breakthrough in the treatment of chronic intractable knee pain following total knee arthroplasty. The periarticular approach has several advantages, including only small incisions over the lateral and medial knee, proximal thigh and abdomen resulting in minimal strain on the lead array with flexion and extension contributing to overall stability of this system.

Keywords: Chronic intractable pain, knee joint pain, neuromodulation, peripheral nerve field neuromodulation (PSFS), peripheral subcutaneous field stimulation, peripheral subcutaneous implant, subcutaneous targeted neuromodulation (STN), total knee arthroplasty

Conflict of interest: The authors reported no conflicts of interest.

COMMENTS:

Peripheral neuromodulation is gaining wider acceptance either in the form of peripheral subcutaneous field stimulation or targeted periph- eral nerve stimulation for intractable chronic pain states of various etiologies. This is a very good work that adds to the already extensive applications of peripheral neuromodulation. Although it includes just two patients, this series opens a new mode of treatment for patients who derive insufficient pain relief from conventional treatments and it is less invasive than dorsal column stimulation. The authors have given a very good account of knee innervation and why peripheral field neurostimulation would be effective. Only long term follow up will tell us how stable the leads would be in their implanted position. Certainly more work is needed to recommend it as an alternative and I am sure we will read more about this application in future. All in all a very good effort and is worth disseminating to colleagues already into peripheral neuromodulation as well as others not aware of this mode of pain relief.

Dr. Riaz Khan Khyshza

Consultant in Anesthesia and Pain Management Royal Free Hospital London, United Kingdom

This article shows still another application of the new and growing field of Peripheral Subcutaneous Field Stimulation. Intractable pain following total knee arthroplasty is a difficult condition to treat. The pain is usually severe and it substantially impairs the ambulatory capabilities of the affected individual. Neurostimulation options until now included spinal cord stimulation or intraspinal nerve root stimulation. Both require electrode placement in the spinal canal. The authors have successfully reduced the pain in two patients who had undergone arthroplasty by placing the leads in the subcutaneous tissues around the knee. The stimulation of the small peripheral nerve fibers resulted in a significant reduction of the pain. This modality, if proven to have good results in a larger number of patients, could become the preferred neuromodulation option in patients with “failed” knee arthroplasty.

Giancarlo Barolat, MD

Director Barolat Neuroscience Presbyterian/St. Luke’s Medical Center Denver, Colorado, USA