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Tayyebeh Lakzaei 
, Alireza Sadeghi , Abdolreza Esmaeilzadeh , Ali Ammari , Saeideh Mazloomzadeh , Arezoo Karimi Moghaddam , Mahnaz Ghaebi *1 , Niloofar Khoshnam Rad
, Alireza Sadeghi , Abdolreza Esmaeilzadeh , Ali Ammari , Saeideh Mazloomzadeh , Arezoo Karimi Moghaddam , Mahnaz Ghaebi *1 , Niloofar Khoshnam Rad
1- , mahnaz.ghaebi@yahoo.com
Abstract: (20 Views)
Background and objectives: Although the therapeutic role of platelet-rich plasma (PRP) in knee osteoarthritis (OA) is increasingly investigated, its efficacy over placebo remains debated. Recent meta-analyses suggest only modest, short-lived benefits without lasting improvement at 12 months. To minimize interindividual heterogeneity, we conducted a randomized, double-blind, within-patient, contralateral-knee comparison of a single PRP injection versus saline placebo.
Materials and methods: Thirty patients with symptomatic bilateral knee OA and identical radiographic Kellgren–Lawrence grade (II or III) in both knees received a single intra-articular injection of PRP in one knee and normal saline in the other, according to randomized allocation. The treating physician was unblinded, whereas patients and outcome assessors were blinded. Outcomes were recorded at baseline and 6 weeks post-injection using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC; pain, stiffness, physical function) and a 100‑mm visual analog scale (VAS) for pain.
Results: In PRP-treated knees, significant within-knee improvements were observed for VAS and all WOMAC subscales (pain: p=0.005; stiffness: p=0.024; function: p=0.005; total WOMAC: p=0.005; VAS: p=0.001). In placebo-treated knees, only VAS showed a significant decrease (p=0.012). Between-group analysis revealed a significant difference solely in the change in physical function (mean difference: 130.5 vs. 51.5; p=0.042), with no significant differences for pain, stiffness, total WOMAC, or VAS at 6 weeks.
Conclusion: A single PRP injection yielded significant within-knee improvements but was not superior to placebo for most outcomes, except physical function. These results are consistent with recent meta-analyses indicating weak, transient PRP efficacy. The pronounced placebo response and short follow-up limit clinical interpretability. The possibility of systemic PRP effects remains speculative and warrants further investigation with biomarker-supported study designs.
Materials and methods: Thirty patients with symptomatic bilateral knee OA and identical radiographic Kellgren–Lawrence grade (II or III) in both knees received a single intra-articular injection of PRP in one knee and normal saline in the other, according to randomized allocation. The treating physician was unblinded, whereas patients and outcome assessors were blinded. Outcomes were recorded at baseline and 6 weeks post-injection using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC; pain, stiffness, physical function) and a 100‑mm visual analog scale (VAS) for pain.
Results: In PRP-treated knees, significant within-knee improvements were observed for VAS and all WOMAC subscales (pain: p=0.005; stiffness: p=0.024; function: p=0.005; total WOMAC: p=0.005; VAS: p=0.001). In placebo-treated knees, only VAS showed a significant decrease (p=0.012). Between-group analysis revealed a significant difference solely in the change in physical function (mean difference: 130.5 vs. 51.5; p=0.042), with no significant differences for pain, stiffness, total WOMAC, or VAS at 6 weeks.
Conclusion: A single PRP injection yielded significant within-knee improvements but was not superior to placebo for most outcomes, except physical function. These results are consistent with recent meta-analyses indicating weak, transient PRP efficacy. The pronounced placebo response and short follow-up limit clinical interpretability. The possibility of systemic PRP effects remains speculative and warrants further investigation with biomarker-supported study designs.
Keywords: Osteoarthritis, Injections, Intra Articular, Platelet Rich Plasma, Visual Analog Scale, Western Ontario and McMaster Universities Osteoarthritis Index.
Type of Study: Clinical Trials |
Subject:
Clinical Medicine
Received: 2025/12/27 | Accepted: 2026/10/18
Received: 2025/12/27 | Accepted: 2026/10/18
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Journal of Advances in Medical and Biomedical Research by Zanjan University of Medical Sciences is licensed under CC BY-NC 4.0
