A comparative 3D anatomical simulation study of four techniques to ablate the infrapatellar branch of the saphenous nerve.

Abstract

Background: Image-guided radiofrequency ablation of the superior and inferior medial genicular nerves is used to treat medial knee pain. The infrapatellar branch (saphenous nerve) has been suggested as an additional nerve target. No studies have assessed nerve capture rates of the techniques.

Objective: To simulate four radiofrequency ablation techniques (cooled/long-axis/conventional bipolar strip lesion/dual-tined techniques) to (1) visualize the lesions in 3D relative to the treatment line and compare their extent; (2) determine and compare capture rates of the infrapatellar branch and inferior medial genicular nerve; and (3) assess which technique(s) would be most effective.

Design: Anatomical simulation study.

Methods: 3D models were reconstructed, based on previously collected data of the dissection/digitization of 7 specimens. Four techniques were simulated with lesion sizes obtained from previously published data or manufacturer's specifications. Capture rates of the infrapatellar branch and inferior medial genicular nerve were compared and the extent of the lesion relative to the treatment line was visualized.

Results: The cooled monopolar technique resulted in over 50% capture rate of the superior infrapatellar branch and anterior branch of inferior medial genicular nerve. This was followed by the dual-tined monopolar technique, capturing 42.9% of superior infrapatellar branch and 57.1% of anterior branch of inferior medial genicular nerve. The simulated lesions did not always encompass the treatment line inferiorly, sparing the inferior infrapatellar branch. All techniques resulted in complete sparing of the infrapatellar branch in some specimens.

Conclusions: High-fidelity lesion simulation of radiofrequency ablation techniques provides a robust anatomical foundation to inform image-guided interventions for medial knee pain.