Identification of the Infrapatellar Branch of the Saphenous Nerve for Treatment Using a Peripheral Nerve Stimulator: A Technical Report

The infrapatellar branch of the saphenous is becoming a common therapeutic target for the diagnosis and treatment of anterior knee pain. It is a nerve commonly injured during knee surgeries, resulting in neuroma formation and chronic neuropathic pain states, and can also transmit nociceptive input in patients with non-surgical anterior knee pain of multiple etiologies. After diagnosing infrapatellar saphenous neuralgia, the nerve is safely ablated using radiofrequency ablation, neurolytic solutions, and, most recently, cryoablation using the handheld iovera® cryoablation system (Myoscience, Inc. Fremont, CA). The iovera® technology benefits from procedural simplicity in that the nerve doesn’t specifically need to be identified and the described technique involves treating a long line over which the infrapatellar branch of the saphenous nerve is expected to course. However, there is significant variability in the course of the nerve and much of the area treated misses the actual location of the nerve, wasting time and potentially increasing patient discomfort and risk of complications. To address these limitations we endeavored to identify a way to more precisely treat the specific location of the nerve thereby optimizing treatment success and procedural simplicity. Using a MiniStim® peripheral nerve stimulator (Halyard Health, Inc., Georgia, US) to scan for the nerve along the previously described treatment line, we have been able to identify a more precise location of the nerve and optimize the treatment target area. This non-invasive identification technique has, to our knowledge, not been previously described.