Randomized Trial in knEe Osteoarthritis Using Low Intensity Ultrasound - Evaluating Feasibility (RELIEF)

Inclusion Criteria: * over 40 years of age; * have medial tibiofemoral compartment knee OA; * have mild to moderate medial compartment radiographic OA severity (determined by the attending surgeon and/or Advanced Practice Physiotherapist on the basis of a standing x-ray or MRI scan depending upon which is available at initial consult); * have stable ('not getting worse or better overall despite short-term fluctuations during the past three months') pain having an average intensity ≥ 3 and ≤ 8 on an 11-point verbal numeric rating scale, VNRS) in one knee which is aggravated by activity and eased with rest; * limited pain from other lower extremity joints; and * no change in first line pain medication in the past 2 months and willingness to forego alterations in pain medication for the duration of the study unless deemed medically necessary. Exclusion Criteria: * history of traumatic OA or previous surgical intervention in the knee or knee effusion; * intra-articular injection of the knee in the previous 6 months; * received ultrasound treatment for knee OA within the past 6 months; * body weight changed ≥ 5% in the past 2 months; * level of physical function insufficient to perform the required assessments or administer the intervention (e.g. intermittent claudication, severe peripheral neuropathy, active proliferative retinopathy, unstable cardiac or pulmonary disease, disabling stroke, chronic pain, arthritis in joints other than the study knee, bone fracture in the past 3 months); * conditions listed as precautions or unknown safety risks for using the EXOGEN EXPRESS ultrasound device (pregnant or nursing women, individuals with thrombophlebitis, vascular insufficiency, abnormal skin sensitivity, sensory paralysis, open wound at the medial joint line of the knee, taking steroids/anti-coagulants, prescription non-steroidal anti-inflammatory, calcium channel blocker or applying the EXOGEN EXPRESS in close proximity to someone wearing a cardiac pacemaker); * unable to read, write and/or understand English; * other illness or reasons judged by the participant, clinicians or researchers to make participation inadvisable (e.g. plans to move or travel, cognitive deficit resulting in difficulty comprehending and complying with instructions, caregiving demands/lack of social support for participation); * unwillingness to sign informed consent; or * participation in a competing study.