(Kiosk 5) Peripheral Nerve Stimulation of the Infrapatellar Branch of the Saphenous Nerve for Treatment of Refractory Knee Pain in a Patient with Pigmented Villonodular Synovitis: A Case Report

Case Diagnosis: A 43-year-old woman with chronic bilateral knee pain refractory to numerous treatment modalities.

Case Description or Program Description: 43-year-old woman with a history of pigmented villonodular synovitis (PVNS) leading to chronic bilateral knee pain that began in 2005. She failed interventions including therapy, corticosteroid injections, arthroscopy with excision of knee mass secondary to PVNS in 2005, bilateral total knee arthroplasty in 2012 and revision in 2016, and genicular nerve blocks and radiofrequency ablation (RFA) in 2018. The patient then trialed spinal cord stimulation (SCS) in 2021 with paddles directed to T9-T11 targeting her area of knee pain. She initially had good pain relief with the SCS trial and proceeded with permanent SCS placement. After the SCS placement, her pain was unable to be captured despite efforts to verify lead positioning with x-ray imaging and multiple attempts to reprogram the device. Eventually the SCS was removed as the battery was causing her issues. Given poor pain relief an attempt to trial a genicular nerve block and then RFA in late 2021 was pursued and resulted in 3 months of relief. The pain gradually started to return therefore a trial of an infrapatellar branch of the saphenous nerve block followed by a peripheral nerve stimulation (PNS) trial was offered.

Setting: Outpatient Tertiary Care Academic Center

Assessment/Results: he patient returned in October 2022 for PNS trial which resulted in decreased Oswestry Disability Index, improved sleep, and a reduction in opioid usage as the frequency of hydrocodone from four times-per-day to two times-per-day. Permanent PNS placement was conducted January 2023. At two months post placement she continues to report adequate bilateral knee pain relief.

Discussion (relevance): Peripheral nerve stimulation of the infrapatellar branch of the saphenous nerve is an emerging and novel option to help provide relief in chronic knee pain refractory to other treatment, and its use continues to grow as more research is conducted to demonstrate its effectiveness.

Conclusions: Management of chronic knee pain in post total knee replacement continues to be a difficult issue for pain medicine physicians. This case emphasizes the benefits of peripheral nerve stimulation for post total knee arthroplasty pain management.