Radiofrequency Ablation of Saphenous Nerve for Chronic Knee Pain

A research article proposes a radiofrequency ablation technique that targets the infrapatellar branch of the saphenous nerve in patients with chronic knee pain that has not responded to conservative management.
Targeting the infrapatellar branch of the saphenous nerve may improve outcomes following genicular nerve radiofrequency ablation for osteoporosis-related chronic knee pain.

A technique for radiofrequency ablation that has been based on updated anatomic studies and may better relieve difficult-to-treat knee pain has recently been described in a review article published in Pain Medicine.

Genicular nerve radiofrequency ablation (GNRFA) has become a more frequently used therapeutic approach for individuals with chronic osteoarthritis-related knee pain, particularly in the setting of conservative treatment failure or when surgery is not an option.

The traditional GNRFA protocol involves targeting the superior lateral and medial genicular nerves and the inferior medial genicular nerve. However, there is significant variability in the location of these nerves, which could make outcomes of this protocol inconsistent and dependent on patient anatomy.

As such, there has been interest in targeting the infrapatellar branch of the saphenous nerve (IPBSN), which innervates the skin over the patellar ligament. The IPBSN is the most commonly damaged nerve during knee arthroplasty and may be a source of persistent pain among patients experiencing postsurgical pain. In addition, cryoneurolysis or pulsed radiofrequency therapies targeting the IPBSN have had comparable outcomes as thermal GNRFA using the traditional protocol.

To target the IPBSN, a radiofrequency strip lesion positioned vertically from 4 cm medial to the tibial tubercle to 4 cm medial to the inferior pole of the patella will capture the IPBSN in 95% of patients. During the procedure, the patient should be in a supine position with the knee in 30 degrees of flexion. The cannulae should enter the knee approximately 1 cm medial to the ISPBN radiofrequency strip lesion.

Depending on patient needs and anatomy, conventional cannula bipolar palisade strip lesion, cooled radiofrequency ablation, dual-tined bipolar radiofrequency ablation, and long axis monopolar radiofrequency ablation techniques can be adapted to target the IPBSN.

Potential safety concerns of radiofrequency ablation of the IPBSN include thermal lesions of the skin or pes anserine tendons, as well as the increased risk for infection in postsurgical knees. The authors of the technique recommend that a prescreening ultrasound be performed to best inform treatment planning. They also advise that clinical studies are needed to evaluate the safety and efficacy of radiofrequency ablation targeting the IPBSN.

The technique authors concluded, “Targeting the IPBSN is feasible and may improve the effectiveness [of] GNRFA. The proposed technique for image guided IPBSN radiofrequency ablation should be both safe and accurate, and accounts for multiple patient related factors which will impact selection and approach. Improved outcomes such as reduced pain, improved quality of life, and reduction of opioid use will likely be further amplified with a more comprehensive genicular radiofrequency ablation protocol that includes IPBSN and other targets.”

Disclosure: One author declared an affiliation with a biotech, pharmaceutical, and/or device company. Please see the original reference for a full list of authors’ disclosures.

Reference

Beckwith M, Cushman D, Clark T, et al. Radiofrequency ablation of the infrapatellar branch of the saphenous nerve for the treatment of chronic anterior inferomedial knee pain. Pain Med. Published online July 22, 2022. doi:10.1093/pm/pnac108

This article originally appeared on Clinical Pain Advisor

References:

Beckwith M, Cushman D, Clark T, et al. Radiofrequency ablation of the infrapatellar branch of the saphenous nerve for the treatment of chronic anterior inferomedial knee pain. Pain Med. Published online July 22, 2022. doi:10.1093/pm/pnac108