This project is one of four components of a thematic project that aims to evaluate the use of ultrasound in regional and infiltration blocks, called "Use of ultrasound in regional blocks and infiltration for the treatment of acute and chronic pain".

It aims to evaluate quantitatively and qualitatively the knee pain control in patients with osteoarthritis after neurotomy by saphenous nerve radiofrequency guided by ultrasound , compared to neurotomy by radiofrequency of genicular nerves guided by fluoroscopy .

Differences between total consumption of analgesics, side effects of medications , impact on quality of life and functional capacity in patients undergoing saphenous nerve neurotomy by radiofrequency guided by ultrasound compared to neurotomy by radiofrequency of genicular nerves guided by fluoroscopy, will also be evaluated.

BACKGROUND: Osteoarthritis of the knees is currently a major public health problem, with patients suffering from pain and functional limitation. Depending on the severity of the impairment, the definitive treatment is surgical, but the old ages often associated and morbidities present in these patients some times limit such conduct. More effective treatments for pain control are necessary.

OBJECTIVES: To evaluate quantitative and qualitative pain control in patients with osteoarthritis in knees after neurotomy of saphenous nerve by radiofrequency guided by ultrasound, compared to neurotomy by radiofrequency of genicular nerves guided by fluoroscopy.

METHODS: This was a prospective, randomized clinical study and blind to the evaluators. Will include 20 patients with knee osteoarthritis grade III or IV, refractory to medical treatment. A group will be submitted to neurotomy by radiofrequency of genicular nerves guided by fluoroscopy and the other group will receive neurotomy by radiofrequency of saphenous nerve, guided by ultrasound. They will be assessed in pain intensity at rest and movement, functionality, satisfaction and adverse effects related to treatment. Patients will be evaluated 15 days, 1 month, 3, 6 and 12 months after the procedure.

Inclusion Criteria:

• Will be included patients older than 18 years, who have moderate to strong chronic pain in knee on most of the days days for at least 3 months, with osteoarthritis of the knee documented by graded radiologically at 3 to 4 in Kellgren-Lawrence rating, refractory to medical treatment (physical therapy, oral analgesics, intra-articular injections of hyaluronic acid or corticosteroids).

Exclusion Criteria:

• The exclusion criteria are: acute knee pain, prior surgery on the knee, another connective tissue disease affecting the knee, psychiatric or neurological disorders, intra-articular injection of hyaluronic acid or corticosteroid for less than 3 months, pain related to nerve sciatic, use of anticoagulants and pacemaker.