Due to scarce published articles about this subject, the researchers aim to study the volume measurements of the brain cortex of patients with primary severe knee osteoarthrosis and those with chronic knee pain compared to healthy and non-symptomatic volunteers, correlating the neuroimaging of cerebral volumetry with pain intensity, pain duration, knee function and pressure pain threshold.

The protocol was designed to include 31 patients in each observational arm, either patients with severe knee osteoarthrosis and chronic knee pain or healthy and non-symptomatic volunteers.

The researchers performed anamnesis to collect clinical and demographic information, the intensity of pain was assessed by the self-rated Visual Analogue Scale (VAS), the pressure pain threshold was evaluated with an algometer, the knee function was assessed with the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scale and the images were collected with the use of the Magnetic Resonance.

Covariates, such as age, gender, Body Mass Index (BMI) and comorbidities as diabetes, cardiac diseases, pulmonary diseases, endocrine diseases and the practice of physical activities were also collected.

Inclusion Criteria:

• Age above 60 years old;
• Both genders;
• Clinical diagnosis of knee osteoarthrosis;
• Self-rated VAS moderate to severe (VAS > 4);
• Pain duration longer than 3 months prior to the evaluation;
• Signed Informed Consent;
• Light physical activity practice or sedentary (healthy volunteers only).

Exclusion Criteria:

• Presence of psychiatric disorders;
• Presence of fibromyalgia;
• Presence of rheumatologic diseases;
• Presence of previous knee surgery;
• Presence of clinical symptoms (healthy volunteers only);
• Presence of knee pain on the previous 6 months (healthy volunteers only);
• History of neoplasia.

Healthy patients and patients with primary severe knee osteoarthrosis and with chronic knee pain were included.