Study suspended due to Covid-19 pandemic.

This is a double-blind placebo controlled trial whose objective is to understand how much the radial extracorporeal shockwave therapy can improve function of patients with knee osteoarthritis.

For this trial, patients with knee osteoarthritis, after signing the informed consent form and having their demographic and baseline information collected, will be randomly allocated into one of both treatment arms: radial extracorporeal shockwave therapy (rESWT) or sham radial extracorporeal shockwave therapy. Then, they will undertake three sessions of rESWT, for three weeks, i.e. one session per week.

Patients will be assessed prior to the therapy, one week after the end of the therapy and three months after the end of the therapy, and the primary outcome of this study is the functional change measured by the Knee injury and Osteoarthritis Outcome Score (KOOS) validated in Portuguese, three months after the end of the therapy.

Secondary outcomes, will be the change of pain, the change of pressure pain tolerance threshold, change in diffuse noxious inhibitory control (DNIC), and thermographic changes.

Inclusion Criteria:

• Clinical diagnosis of knee osteoarthritis;
• Onset knee pain with moderate or severe intensity: Visual Analogue Scale (VAS) > 4;
• Onset knee pain over 3 months prior to the inclusion;

Exclusion Criteria:

• Presence of psychiatric disease;
• Presence of fibromyalgia;
• Presence of systemic inflammatory rheumatic diseases;
• History of neoplasia;
• Presence of clinical diseases in other joints;
• Ongoing use of anticoagulant drugs.