Cooled radiofrequency ablation versus cryoneurolysis of the genicular nerves for the symptomatic pain management in knee osteoarthritis: a study protocol of a prospective, randomized, single-blinded clinical trial

Abstract

Background: Cooled radiofrequency ablation (CRFA) and cryoneurolysis (CRYO) are two novel methods of genicular neurolysis to relief pain in symptomatic knee osteoarthritis (KOA). In this study, the two methods will be compared, giving us the opportunity to investigate their efficacy, safety and complications.

Methods: In this prospective randomized trial 70 patients with KOA will be recruited using a diagnostic block of four genicular nerves. Two groups will be created through software randomization: a CRFA group (35 patients) and a CRYO group (35 patients). The target of the interventions will be four genicular nerves; the superior medial, superior lateral, inferior medial, as well as the medial (retinacular) genicular branch from vastus intermedius. The primary outcome of this clinical trial will be the efficacy of CRFA or CRYO at 2-, 4-, 12-and 24-weeks post-intervention using the Numerical Rating Pain Scale (NRPS). The secondary outcomes are the safety of the two techniques, as well as the clinical evaluation using the Knee Injury and Osteoarthritis Outcome Score (KOOS), the Oxford Knee Score (OKS), and the 7-point scale of Patient Global Impression of Change (PGIC).

Discussion: These two novel techniques can block pain transmission through genicular nerves in different ways. In contrast to cryoneurolysis, the CRFA method has been well documented in the past. This is the first clinical trial to compare CRFA vs CRYO and draw conclusions about their safety and efficacy.

Trial registration: ISRCTN87455770 [ https://doi.org/10.1186/ISRCTN87455770 ]. Registered 29/3/2022, first patient recruited 31/8/2022.

Keywords: Cooled radiofrequency ablation; Cryoneurolysis; Genicular nerves; Knee osteoarthritis; Pain.

Fig. 1

Flowchart of the study

Fig. 2

a, b Anteroposterior and lateral radiographs of an arthritic knee showing the intended target-points of the genicular nerves (M1, M2 = SMGN, M3 = IMGN, L1, L2 = SLGN, L3 = MRGN); c intraoperative picture of the needles in the lateral side just prior to ablation d anteroposterior and lateral fluoroscopic images of the exact location of the needles in the lateral side; e intraoperative picture of the needles in the medial side just prior to ablation; f anteroposterior and lateral fluoroscopic images of the exact location of the needles in the medial side

Fig. 3

Diagram of the proposed power analysis for the 2 groups in 4 different assessment points using rmANOVA