Efficacy of Ultrasound-Guided Genicular Nerve Radiofrequency Ablation Therapy

Our aim in this study is; to investigate the superiority and long-term effectiveness of radiofrequency ablation therapy applied with 5 nerves, 3 nerves and 2 nerves on fall risk, balance, proprioception, chronic pain and symptoms in knee osteoarthritis.

Radiofrequency ablation therapy; it is effective in chronic pain by causing nerve damage. Application of radiofrequency ablation therapy on chronic knee pain with different protocols has been reported in the literature with different results.

In the literature, it has been shown that the 5-nerve protocol versus the 3-nerve protocol with the radiofrequency ablation method reduces pain and provides functional improvement in patients with chronic knee osteoarthritis. In another study in the literature, functional and physical performance was examined with a 3-nerve protocol in the same patient group without a control group and was found effective.

To our knowledge, there is no study in the literature evaluating the effectiveness of radiofrequency ablation therapy on fall risk, balance and proprioception after applying different protocols in knee osteoarthritis.

There are few studies in the literature regarding radiofrequency ablation treatment procedures for knee osteoarthritis. In line with this information, it is obvious that more studies are needed on the radiofrequency ablation method. Although this method has been shown to be effective and popular in recent years, since it is an invasive procedure, another aim of ours is to reveal what is the least intervention that will give the most effective results for patients.

Diagnostic genicular nerve block: It will be performed by injecting lidocaine (%2, 2 cc) into the superıor lateral (SL), superıor medial (SM) and inferior medial (IM) branches of the genicular nerve passing through the periosteal areas connecting the femoral shaft to the bilateral epicondyles and the tibia shaft to the medial epicondyle.

All patients who meet the study eligibility criteria will undergo a diagnostic genicular nerve block before the procedure, and patients with a decrease in VAS (visual analog scale) of more than 50 percent for more than 24 hours will be considered for the RFA procedure. Injection will be performed under ultrasound guidance using a 12 Mhz linear array transducer probe (GE Logiq P9, GE Healthcare, Boston, MA).

The patients are randomly divided into 3 groups with the help of a computer-based randomization program. One group will be treated with the RFA method for 2 nerves (SM, IM), the other group will be treated with 3 nerves (SM, SL, IM), and the other group will be treated with a single treatment session for 5 nerves (SM, SL, IM, Rekurrent fibular nerve-RFN, Infrapatellar branch of saphenous nerve-IPBSN).

Before the RFA procedure, all participants will be anesthetized with 1 cc %1 lidocaine under sterile conditions, in a supine position, with a pillow placed under the popliteal fossa, and the skin and subcutaneous tissues on the surface of the targeted nerves.

RFA application sites will be determined by finding the arteries between the shaft and epicondyles of the femur and tibia with the help of Color Doppler Ultrasound. The infrapatellar branch of the saphenous nerve (IPBSN) will be confirmed by Doppler Ultrasound of the artery of the nerve 4 cm medial to the apex of the patella and tibial tubercle. Recurrent fibular nerve (RFN) will be confirmed by Doppler Ultrasound of the nerve artery along the caudate line of Gerdy's tubercle, 1 cm below the tuberosity tibia. For the RFA procedure, a 10 cm long, 22 gauge RF cannula with a 10 mm active tip (Model SC-K, Top Neuropole, MPS Medical Product Service GmbH, Germany) will be used.

In order to increase the accuracy of the location determined by ultrasound, sensory stimulation will be applied at a frequency of 50 Hz and with a threshold value lower than 0.6 volts. In order to prevent the motor nerves from being affected, the absence of lower extremity muscle fasciculations in the relevant area will be confirmed with 2 volt stimulation at 2 Hz frequency. The RFA process will be applied to the existing nerves via a generator (TOP Lesion Generator TLG-20, MPS Medical Product Service GmbH, Germany) at 42 C, as pulse RFA for 120 seconds.

To address any discomfort that may occur after the procedure, a total of 2 cc of betamethasone (5 mg+2 mg/1 cc) and %2 lidocaine (1 cc) will be injected into the points where RFA is applied, after aspiration.

For participants who will not be injected at more than 2 points, the same procedure will be applied without activating the generator in order to ensure that the participants remain blind to group allocation and only 2 cc % 0,9 NaCl will be injected into the treatment points. After the procedure, patients will be advised to continue their current medication and exercise therapy. Patients will not receive other pain treatments such as physical therapy, knee re-RFA treatment, intra-articular hyaluronic acid, steroid or similar injection treatments for 3 months.

Inclusion criteria

• Age between 30-75
• Chronic knee pain that lasts at least 6 months
• Radiographic confirmation of osteoarthritis: Presence of Grade 3 or 4 radiographic changes characterized by significant narrowing in the medial space of the tibiofemoral joint according to the Kellgren-Lawrence classification system
• Knee pain >40 mm when performing one of the two movements that cause the most severe pain (sitting to standing or going up and down stairs) according to 100 mm VAS

• 50% reduction in VAS with diagnostic genicular nerve block

Exclusion criteria

• Presence of systemic inflammatory disease such as rheumatoid arthritis
• Previous RFA treatment to the knee or hyaluronic acid or steroid injection to the knee within the last 3 months
• History of previous knee surgery
• Clinically significant structural abnormalities other than osteoarthritis that may lead to chronic knee pain
• Having undergone physical therapy to the knee in the last 6 months or a history of knee trauma
• Application of other pain treatments
• Body-Mass İndex <18 and >40 kg/m2
• Pregnancy
• Presence of uncontrolled serious illness (cancer, diabetes, etc.), infection, psychiatric disorder, coagulation disorder