The Effect of Focused Ultrasound on Pain in Moderate-to-Severe Knee Osteoarthritis

INTERVENTION: Focused ultrasound (focused ultrasound energy) will be transcutaneously applied to the saphenous nerve under imaging ultrasound guidance in participants with moderate‐to‐severe knee osteoarthritis. The procedure will occur only once in an outpatient clinic and be completed by a sports medicine physician. It will take approximately 10‐15 minutes. This is a dose‐response study, where participants will be randomised to one of four cohorts of four subjects each (9W, 18W, 27W) and the degree and duration of pain relief assessed on a per‐cohort basis. Each participant within a cohort will receive the same dose. CONDITION: Knee Osteoarthritis; ; Knee Osteoarthritis Musculoskeletal ‐ Osteoarthritis PRIMARY OUTCOME: Change in medication consumption, as measured by percentage change in medication dosage on Days 1, 3, 5 and 7 post‐procedure (patient report via study‐specific questionnaire)[Days 1, 3, 5 and 7 post‐procedure] Change in pain intensity, as measured by percentage change in numerical rating scale (NRS) with the chosen activity on Days 0, 1, 3, 5 and 7 post‐procedure.; [Days 0, 1, 3, 5 and 7 post‐procedure] SECONDARY OUTCOME: Total frequency and severity of adverse events in accordance with the Common Terminology Criteria for Adverse Events (CTCAE 5.0) ; ; Potential adverse events include: ; ‐ Temporary altered sensation ; ‐ Temporary muscle tenderness ; ‐ Temporary skin irritation/redness[Days 0, 1, 3 and 7 post‐procedure] INCLUSION CRITERIA: 1. Adults >= 18 years of age with Medicare coverage. 2. Participants with medial knee osteoarthritis, where: a) Knee osteoarthritis is defined according to American College of Rheumatology criteria (knee pain, aching or stiffness on most of the past 30 days and evidence on radiograph of knee osteoarthritis). b) Participants have evidence of disease in the medial compartment on a radiograph, where evidence of disease in the medial compartment in radiographs is defined as at least grade 2 on the Kellgren and Lawrence system. 3) Knee pain of at least 5 out of 10 when performing one of two movements that elicit the worst pain: standing from a seated position and a slow squat (90 degrees). 4) Knee pain is reported in the medial knee as documented on the knee pain map. 5) A diagnostic nerve block of the infrapatellar branch of the saphenous nerve results in a >=50% reduction in the NRS pain assessment score in knee pain when performing the activity