Revised Targets for Knee Radiofrequency Ablation

This study applies a modified ultrasound-guided radiofrequency ablation (RFA) protocol for targeting the genicular nerves, informed by recent anatomical research. Conventional genicular nerve RFA techniques commonly rely on fluoroscopic or ultrasound guidance based on standard anatomical landmarks. However, cadaveric studies-such as those by Fonkoue et al. (2021)-have shown that these conventional approaches frequently miss the intended nerves, particularly the superomedial and superolateral branches, leading to inconsistent or suboptimal outcomes.

To address these limitations, this protocol incorporates revised probe positioning and alternative bony landmarks aligned with verified nerve pathways. The updated targeting strategy is designed to improve the precision and reproducibility of genicular nerve localization using high-resolution musculoskeletal ultrasound.

The procedure begins with ultrasound identification of the target genicular nerves. Once confirmed, a local anesthetic (2% lidocaine, 20-40 mg per site) is infiltrated to minimize discomfort. Thermal lesioning is then performed using standard 20G RF cannulas at 85°C for 90 seconds. Sensory stimulation (0.2-0.5 V) is used to verify appropriate referral patterns, and motor stimulation (2.0 V) is applied to rule out motor involvement before lesioning. If motor responses are elicited, repositioning or procedure cancellation is considered.

This anatomically informed technique aims to enhance procedural accuracy and consistency. By integrating cadaver-based nerve mapping with real-time ultrasound imaging, the approach has the potential to improve treatment effectiveness while maintaining a strong safety profile. The study will contribute clinical data supporting the feasibility and utility of this refined targeting method in managing knee pain related to joint degeneration.

Inclusion criteria

• Patients with chronic knee pain related to radiographic knee osteoarthritis, Kellgren-Lawrence (KL) grade III or IV, who are refractory to conservative treatment.

(Refractoriness to conservative treatment is defined as:

• Persistent pain and functional limitation after undergoing knee-targeted physiotherapy and analgesic medication in accordance with clinical guidelines for osteoarthritis [e.g., paracetamol, nonsteroidal anti-inflammatory drugs, and other drugs as deemed appropriate by the treating physician];
• Persistent pain and functional limitation after intra-articular corticosteroid injections or limited success with such interventions.)

Exclusion criteria

• Patients with previous knee arthroplasty
• Patients who have undergone prior radiofrequency (RF) ablation
• Significant psycho-emotional disorders
• Addictive behaviors
• Generalized pain
• Nociplastic pain
• Presence of a pacemaker
• Presence of osteosynthesis material in the knee or adjacent anatomical regions