Genicular radiofrequency ablation seems to be a safe, effective and minimally invasive therapy for chronic knee OA patients who have had a positive diagnostic block. No study has determined whether genicular radiofrequency ablation can relieve chronic post-arthroplasty knee pain. The investigators propose to examine the effect of genicular radiofrequency ablation in chronic post-arthroplasty knee pain in patients who respond positively to diagnostic nerve blocks.