Intra-articular injection of gold micro-particles for painful knee osteoarthritis

Abstract

Background: Gold microparticles injected intra-articular in knee osteoarthritic joints (OA) may provide pain relief. The present open, exploratory study sought to identify the efficacy and factors associated with the outcomes. Methods: This study included thirty patients with knee OA who received intraarticular injections with 20 mg gold microparticles (72.000 particles, 20–40 µm in diameter) using the patient’s synovial fluid as the carrier, and 136 patients with knee OA who received 20 mg gold microparticles using hyaluronic acid as the carrier. In the analysis, we included the Global Rating of Change Scale, PainDetectQuestionnaire (PDQ), the use of a carrier, Body Mass Index (BMI), and Kellgren Lawrence score at the inclusion, Western Ontario, and McMaster Universities Osteoarthritis Index (WOMAC) sub-scores for pain, stiffness, and function at inclusion and two years. Results: On the Global Rating Change Scale, 72.9% of patients reported a positive effect, 23.5% no effect, and 2.4% worse. PDQ and the three WOMAC subscores all improved at two years of follow-up. The use of carrier did not influence the effect at two years of follow-ups corrected for the other selected co-variables (P = 0.36). PainDetect ≥ 13 (P = 0.0027), BMI (P = 0.008) and Kellgren-Lawrence grade 4 (P = 0.049) at inclusion reduced the effect with a minor odds ratio compared to the baseline effect of treatment (P = 0.03). WOMAC subscores at inclusion did not influence the effect (P > 0.5). Conclusions: A single intra-articular injection of gold microparticles was associated with pain reduction and improved function in patients with knee OA. Neuropathic pain, obesity, and severe osteoarthritis, to a minor degree, reduced the effect of intra-articular gold microparticles for knee OA. Trial registration The study followed the principles of the Declaration of Helsinki and was approved by the local ethics committee of the North Denmark Region by 27/07/2016 (N-20160045). The regional data protection agency approved the project by 06/07/2016 (2008-58-0028, ID 2016-116) and registered in ClinicalTrial.Gov by 04/01/2018 (NCT03389906).