Evidence map›Paper›PMID 41387884›Full record

Trial reportJournal of orthopaedic surgery and research2025

A prospective, open-label, clinical investigation of a single intra-articular polyacrylamide hydrogel injection in participants with knee osteoarthritis: a 5-year extension study.

Henning Bliddal, Andreas Hartkopp, Jannie Beier, Philip G Conaghan, Marius Henriksen

Registry-linked trialAbstract readMulticenter StudyClinical Trial
PubMed Full text at PMC Publisher
In one paragraph

Trial report in Journal of orthopaedic surgery and research, 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. It is linked to trial NCT04179552 (Prospective, Open-label Clinical Investigation of Intra-articular Polyacrylamide Hydrogel Injection in Subjects With Knee Osteoarthritis), which is not on this map. Cited by 2 papers.

0numbers the graph read from it
0cells of the map it votes in
2citing papers in PubMed
–field-weighted citation impact
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

NCT04179552 nacompletednot on this map

Prospective, Open-label Clinical Investigation of Intra-articular Polyacrylamide Hydrogel Injection in Subjects With Knee Osteoarthritis

TypeinterventionalSponsorConturaRan2019 to 2024Enrolled49ConditionsOsteoarthritis, KneeArmsPAAG-OA
3 · Its place in the literature

Who cites it

2 citing papers in PubMed.

  1. Article
  2. H-WaveMedicina (Kaunas, Lithuania) · 2025
    Observational
4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

5 authors.

Henning BliddalThe Parker Institute, Bispebjerg-Frederiksberg Hospital, University of Copenhagen, Copenhagen, Denmark. Henning.Bliddal@regionh.dk.
Andreas HartkoppA2 Rheumatology and Sports Medicine, Holte, Denmark.
Jannie BeierReumatologerne Beier & Morillon, Odense, Denmark.
Philip G ConaghanLeeds Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds & NIHR Leeds Biomedical Research Centre, Leeds, UK.
Marius HenriksenThe Parker Institute, Bispebjerg-Frederiksberg Hospital, University of Copenhagen, Copenhagen, Denmark.

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

backgroundKnee osteoarthritis is a highly prevalent and painful joint disorder with limited long-term treatment options. Intra-articular corticosteroids and hyaluronic acid offer only short-term relief and may have safety concerns. This study aimed to evaluate the long-term effectiveness and safety of a single intra-articular injection of 2.5% polyacrylamide hydrogel in individuals with moderate to severe knee osteoarthritis.

methodsThis prospective, multicentre, open-label, single-arm clinical study enrolled 49 participants who received a single 6 mL intra-articular injection of 2.5% polyacrylamide hydrogel. After 1 year, 35 participants entered an extension study with yearly assessments up to 5 years post treatment. The primary outcomes for the extension phase included changes from baseline in WOMAC subscales (pain, stiffness, physical function) and Patient Global Assessment (PGA). Safety was evaluated through the incidence of adverse events. Statistical analyses included a mixed model for repeated measures and sensitivity analyses using ANCOVA and baseline observation carried forward.

resultsOf the 49 participants, 27 completed the five-year follow-up. Statistically significant improvements from baseline were observed in WOMAC pain (-14.6; 95% CI: -21.4 to -7.7; p = 0.0002), stiffness (-19.6; 95% CI: -29.9 to -9.3; p = 0.0006), physical function (-12.5; 95% CI: -19.8 to -5.2; p = 0.0015), and PGA (-13.4; 95% CI: -23.3 to -3.5; p = 0.0100). These improvements were sustained throughout the five-year period. A total of 47 adverse events were reported in the extension study, with no serious events attributed to the investigational device. No new adverse device effects were reported in the extension study.

conclusionsA single intra-articular injection of 2.5% polyacrylamide hydrogel demonstrated sustained improvements in WOMAC pain, stiffness, physical function, and PGA for up to five years, with a favourable safety profile. These findings support its potential as a long-term treatment option for knee osteoarthritis.

trial registrationClinicalTrials.gov Identifier: NCT04179552.

Indexed as

Acrylic ResinsHydrogelsOsteoarthritis, KneeAgedFemaleFollow-Up StudiesHumansInjections, Intra-ArticularMaleMiddle AgedPain MeasurementProspective StudiesTime FactorsTreatment OutcomeAcrylic ResinsHydrogelspolyacrylamide gelsClinical trialIntra-articular injectionKnee osteoarthritisLong term EfficacyLong term safetyPolyacrylamide hydrogelSynovial Implant

Identifiers

PMID41387884
PMCPMC12817702

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Registered trials

Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.