The PERK Study: Predicting and Evaluating Response to Knee RFA Using fNIRS

The goal of this study is collect data for a larger study about using fNIRS to evaluate whether baseline and post-GNRFA cortical activation patterns are associated with clinically meaningful pain relief and improvement in pain-related disability following GNRFA in adults with knee osteoarthritis. While GNRFA is a promising treatment, clinical outcomes remain variable, limiting its widespread adoption. Pain relief following GNRFA may depend not only on anatomically optimized placement, but also on inter-individual differences in central pain processing and modulation reflected in cortical activation patterns. Currently, patient selection for GNRFA is based on response to genicular nerve (GN) blocks, which targets the peripheral sensory innervation. The ability to predict the response to GNRFA from the GN block has been inconsistent. In contrast, fNIRS is a novel, non-invasive and scalable method for assessing cortical activity associated with pain processing and movement-related function. fNIRS may therefore allow clinicians to use cortical activation patterns to select patients most likely to respond to GNRFA, and to objectively quantify response to GNRFA.

This study will have participants complete a combination of in-person visits and remote visits. In-person visits will include fNIRS assessments, questionnaires, the GN block procedure, and the GNRFA procedure if they receive at least 50% pain relief on the GN block. Remote visits will include filling out questionnaires. The questionnaires at all visits will measure pain, mood and quality of life. The primary objective is to obtain preliminary data for estimating effect sizes and informing sample size calculations for a larger study. Secondary objectives including determining whether baseline cortical activation patterns measured using fNIRS is associated with a clinically meaningful treatment response following GNRFA, and to characterize changes in fNIRS activation patterns over time post-GNRFA in responders and non-responders. The results will help determine whether fNIRS may be a feasible, non-invasive way to better select patients to receive GNRFA procedures.

• Radiofrequency ablation alone (Procedure), also known as Genicular Nerve Radiofrequency Ablation: At the week 1 visit, under fluoroscopic guidance, electrodes are positioned at established anatomical landmarks around the knee and thermal lesions are created to disrupt the targeted sensory nerve fibres. There will be a total of six landmarks that are reached through the insertion of three needles. These landmarks are 1) superomedial a) posterior to the medial epicondyle and b) on same distal plane but anterior to the medial epicondyle, 2) superolateral c) posterior to the lateral epicondyle and d) on the same distal plane but anterior to the lateral epicondyle, and 3) Inferomedial e) junction between medial tibial condyle and tibial shaft and f) superiorly and anteriorly to this, along the medial tibial condyle.
• Genicular Nerve Block (Diagnostic test): GN Blocks will be done to determine which patients will proceed to receive a GNRFA. This procedure involves an injection of local anesthetic around the sensory nerves supplying the knee joint. This serves as a diagnostic procedure to confirm that the patient may benefit from the GNRFA, which is completed as part of routine clinical practice. Participants who achieve at least 50% pain relief from the GN block for at least the duration of the local anesthetic (≥4 hours) will be considered suitable candidates for GNRFA, and will proceed within the study.

Primary outcomes

• Cortical Activation Measures [Baseline, 1-hr post-GNRFA and 3-month post-GNRF]: Changes from baseline, to 1hr post-GNRFA, and 3-month post-GNRFA in cortical activation measured using fNIRS will be examined as well as differences in activation patterns between responders and non-responders.

Other outcomes

• Pain and Pain-related Disability [Baseline, GNRFA Procedure, 3-month post-GNRFA, 6-month post-GNRFA, 9-month post-GNRFA, and 12-month post-GNRFA]: The numeric rating scale (NRS), the Western Ontario McMaster Osteoarthritis Index (WOMAC), a Body Diagram, and the Multidimensional Symptom Index will be used to quantify pain and functional response to GNRFA.
• Psychological [Baseline, GNRFA procedure, 3-month post-GNRFA, 6-month post-GNRFA, 9-month post-GNRFA, 12-month post-GNRFA]: The Patient Health Questionnaire-9 (PHQ-9) will be used to assess changes in mood over time.

Sex: All, ages: 18 Years to any

Inclusion Criteria:

* ≥18 years old
* Have osteoarthritis in either knee

Exclusion Criteria:

* Limited English proficiency or lack of capacity to consent (per clinical judgement)
* Scheduled for knee arthroplasty within next 6 months

• Eldon Loh, MD, Principal investigator, Lawson Research Institute