Optimal frequency of platelet-rich plasma injections for managing osteoarthritis: A longitudinal study

Introduction: Recent reviews suggest that PRP injections can improve pain and function more effectively than other treatments; however, consensus on the optimal number of injections is lacking. We aimed to determine the optimal administration frequency and number of PRP injections for management of...

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Main Author: Masahiko Kemmochi
Format: Article
Language:English
Published: Elsevier 2025-06-01
Series:Regenerative Therapy
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Online Access:http://www.sciencedirect.com/science/article/pii/S235232042500032X
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author Masahiko Kemmochi
author_facet Masahiko Kemmochi
author_sort Masahiko Kemmochi
collection DOAJ
description Introduction: Recent reviews suggest that PRP injections can improve pain and function more effectively than other treatments; however, consensus on the optimal number of injections is lacking. We aimed to determine the optimal administration frequency and number of PRP injections for management of osteoarthritis (OA) symptoms, to examine long-term effects and structural improvements with PRP, and to determine correlations between clinical outcomes and imaging findings. Methods: This longitudinal study included 167 patients with knee OA, categorized using the Kellgren–Lawrence (KL) grading system. Participants received up to six PRP injections and were followed-up for 24 months. Pain levels were assessed using the visual analog scale (VAS); functional recovery was measured using the Knee Injury and Osteoarthritis Outcome Score (KOOS). To determine whether PRP can induce sustained structural improvements, we used the MRI Osteoarthritis Knee Score (MOAKS) to monitor changes in bone-marrow lesions (BMLs). Data were analyzed using repeated-measures analysis of variance to identify significant changes in pain and functional outcomes. Results: VAS and KOOS scores significantly improved after PRP treatment. Patients with KL grades 1 and 2 exhibited maximum pain relief after the fourth injection; those with KL grades 3 and 4 showed optimal results after the fifth injection. Improvements were maintained or enhanced at the 24-month follow-up. The effect size increased as the number of treatments progressed, and especially after the fourth treatment, with a Cohen's d values of −1.22, −1.28, and −0.99 (p < 0.0001). Conclusions: PRP injections administered at specific intervals can significantly reduce pain and improve function in patients with OA, with the required frequency depending on disease severity. These findings support the customization of PRP-treatment protocols based on individual patient profiles to maximize therapeutic benefits. Trial registration: This study has been registered with the clinical trial register of the Japan Medical Association Center for Clinical Trials (JMA-IIA00351). Unblinded study registration: This study has been registered with the clinical trial register of the Japan Medical Association Center for Clinical Trials (JMA-IIA00351). Level of evidence: II.
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spelling doaj-art-d16303916a1f4a4aba984fc334c32b0f2025-08-20T01:51:16ZengElsevierRegenerative Therapy2352-32042025-06-012922723610.1016/j.reth.2025.02.006Optimal frequency of platelet-rich plasma injections for managing osteoarthritis: A longitudinal studyMasahiko Kemmochi0Kemmochi Orthopedic Surgery Sports Clinic, 42-1 Higashi-honcho, Ota, Gunma Prefecture 373-0026, Japan.; Kemmochi Orthopedic Surgery Sports Clinic, 42-1 Higashi-honcho, Ota, Gunma Prefecture 373-0026, JapanIntroduction: Recent reviews suggest that PRP injections can improve pain and function more effectively than other treatments; however, consensus on the optimal number of injections is lacking. We aimed to determine the optimal administration frequency and number of PRP injections for management of osteoarthritis (OA) symptoms, to examine long-term effects and structural improvements with PRP, and to determine correlations between clinical outcomes and imaging findings. Methods: This longitudinal study included 167 patients with knee OA, categorized using the Kellgren–Lawrence (KL) grading system. Participants received up to six PRP injections and were followed-up for 24 months. Pain levels were assessed using the visual analog scale (VAS); functional recovery was measured using the Knee Injury and Osteoarthritis Outcome Score (KOOS). To determine whether PRP can induce sustained structural improvements, we used the MRI Osteoarthritis Knee Score (MOAKS) to monitor changes in bone-marrow lesions (BMLs). Data were analyzed using repeated-measures analysis of variance to identify significant changes in pain and functional outcomes. Results: VAS and KOOS scores significantly improved after PRP treatment. Patients with KL grades 1 and 2 exhibited maximum pain relief after the fourth injection; those with KL grades 3 and 4 showed optimal results after the fifth injection. Improvements were maintained or enhanced at the 24-month follow-up. The effect size increased as the number of treatments progressed, and especially after the fourth treatment, with a Cohen's d values of −1.22, −1.28, and −0.99 (p < 0.0001). Conclusions: PRP injections administered at specific intervals can significantly reduce pain and improve function in patients with OA, with the required frequency depending on disease severity. These findings support the customization of PRP-treatment protocols based on individual patient profiles to maximize therapeutic benefits. Trial registration: This study has been registered with the clinical trial register of the Japan Medical Association Center for Clinical Trials (JMA-IIA00351). Unblinded study registration: This study has been registered with the clinical trial register of the Japan Medical Association Center for Clinical Trials (JMA-IIA00351). Level of evidence: II.http://www.sciencedirect.com/science/article/pii/S235232042500032XOptimal frequencyPlatelet-rich plasmaMultiple injectionsKnee osteoarthritisLongitudinal study
spellingShingle Masahiko Kemmochi
Optimal frequency of platelet-rich plasma injections for managing osteoarthritis: A longitudinal study
Regenerative Therapy
Optimal frequency
Platelet-rich plasma
Multiple injections
Knee osteoarthritis
Longitudinal study
title Optimal frequency of platelet-rich plasma injections for managing osteoarthritis: A longitudinal study
title_full Optimal frequency of platelet-rich plasma injections for managing osteoarthritis: A longitudinal study
title_fullStr Optimal frequency of platelet-rich plasma injections for managing osteoarthritis: A longitudinal study
title_full_unstemmed Optimal frequency of platelet-rich plasma injections for managing osteoarthritis: A longitudinal study
title_short Optimal frequency of platelet-rich plasma injections for managing osteoarthritis: A longitudinal study
title_sort optimal frequency of platelet rich plasma injections for managing osteoarthritis a longitudinal study
topic Optimal frequency
Platelet-rich plasma
Multiple injections
Knee osteoarthritis
Longitudinal study
url http://www.sciencedirect.com/science/article/pii/S235232042500032X
work_keys_str_mv AT masahikokemmochi optimalfrequencyofplateletrichplasmainjectionsformanagingosteoarthritisalongitudinalstudy