{
  "abstract": "Background\n\nBasic calcium phosphate (BCP) and calcium pyrophosphate crystals (CPP) are suspected to be part of osteoarthritis (OA) pathogenesis through chondrocyte-, fibroblast-, and leukocyte-mediated inflammation and cartilage destruction. We aimed to determine whether the presence of CPP and BCP in synovial fluid (SF) was associated with pain and inflammation in patients with knee OA.Methods\n\nSF was sampled during the baseline visit of the Intensive Diet vs. Knee Arthroplasty (INKA) trial. BCP and CPP were detected by Raman Spectroscopy (RS). Participants were classified as Calcium crystal positive (CaC+) or negative (CaC-). Pain was evaluated using the KOOS₁₂ Pain subscale. Ultrasound (US) was performed to evaluate medial and lateral synovial hypertrophy/effusion. Continuous and categorical outcomes were analysed using ANCOVA and logistic regression, respectively.Results\n\nFifty-one participants from the INKA trial met the inclusion criteria; 49 samples were analysed using RS. All participants (n = 49) were calcite positive. 29 participants were calcium phosphate positive with BCP (n = 18), CPP (n = 3), or both (n = 8). Estimated between-group difference for KOOS₁₂ Pain was 8.7 points (95% CI: 0.2 to 17.5; P = 00.054) with the CaC + group indicating higher KOOS₁₂ Pain scores (42.32 vs 33.64), i.e. less symptoms. Prevalence of US-detected inflammation was 97% (n = 28) in the CaC + group and 95% (n = 19) in the CaC- group. Estimated odds ratio was 0.85 (95% CI, 0.04 to 20.41; P = 00.92).Conclusion\n\nBCP and CPP positivity in SF was neither associated with knee OA patients' symptoms nor US-detected inflammation.",
  "abstract_shown": true,
  "affiliations": [
    "The Parker Institute, Copenhagen University Hospital - Bispebjerg & Frederiksberg, Copenhagen, Denmark.",
    "Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark.",
    "Department of Orthopaedic Surgery, Copenhagen University Hospital - Amager & Hvidovre, Copenhagen, Denmark.",
    "Department of Orthopaedic Surgery and Traumatology, Copenhagen University Hospital - Bispebjerg and Frederiksberg, Copenhagen, Denmark.",
    "Department of Radiology, Copenhagen University Hospital - Bispebjerg & Frederiksberg, Copenhagen, Denmark.",
    "Research Unit of Rheumatology, Department of Clinical Research, University of Southern Denmark, Odense University Hospital, Odense, Denmark.",
    "Centre for General Practice, Department of Public Health, University of Copenhagen, Copenhagen, Denmark.",
    "Univ. Lille, CHU Lille, Univ. Littoral Côte D'Opale, ULR 4490 - MABLab- Adiposité Médullaire et Os, Lille, F-59000, France.",
    "Dept. of Rheumatology, Hôpital Saint-Philibert, Université Catholique de Lille, Lille, France."
  ],
  "article_type": "research article",
  "arxiv": null,
  "author_total": 13,
  "authors": [
    {
      "affs": [
        0,
        1
      ],
      "name": "Asbjørn Seenithamby Poulsen"
    },
    {
      "affs": [
        0,
        1,
        2
      ],
      "name": "Kristine Ifigenia Bunyoz"
    },
    {
      "affs": [
        0,
        1,
        3
      ],
      "name": "Saber Muthanna Aljuboori"
    },
    {
      "affs": [
        0,
        1,
        4
      ],
      "name": "Camilla Toft Nielsen"
    },
    {
      "affs": [
        0
      ],
      "name": "Anna Døssing"
    },
    {
      "affs": [
        0
      ],
      "name": "Karen Ellegaard"
    },
    {
      "affs": [
        0,
        5
      ],
      "name": "Tobias Haugegaard"
    },
    {
      "affs": [
        0,
        6
      ],
      "name": "Henrik Gudbergsen"
    },
    {
      "affs": [
        0,
        5
      ],
      "name": "Robin Christensen"
    },
    {
      "affs": [
        7
      ],
      "name": "Guillaume Falgayrac"
    },
    {
      "affs": [
        7,
        8
      ],
      "name": "Tristan Pascart"
    },
    {
      "affs": [
        0,
        1
      ],
      "name": "Marius Henriksen"
    },
    {
      "affs": [
        0,
        1
      ],
      "name": "Henning Bliddal"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/b5n19qnq3aghs.bib",
  "cited_by": 0,
  "doi": "10.1016/j.ocarto.2026.100887",
  "fulltext_url": "https://europepmc.org/articles/PMC13695371",
  "id": "b5n19qnq3aghs",
  "issns": [
    "2665-9131"
  ],
  "landing_url": "https://europepmc.org/article/MED/42927365",
  "language": "eng",
  "licence": "CC-BY-NC-ND",
  "licence_label": "CC BY-NC-ND",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by-nc-nd/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "hal",
      "0.sdv"
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    [
      "openalex",
      "2745|Osteoarthritis Treatment and Mechanisms"
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  "pdf_url": "https://europepmc.org/articles/PMC13695371?pdf=render",
  "pmcid": "PMC13695371",
  "pmid": "42927365",
  "published": "2026-10-12",
  "publisher": "Osteoarthritis Research Society International",
  "ris": "https://research.draconitic.com/paper/b5n19qnq3aghs.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:21:18Z",
      "native_id": "MED:42927365",
      "source": "europepmc",
      "url": "https://europepmc.org/article/MED/42927365"
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      "first_seen": "2026-11-04T12:20:53Z",
      "native_id": "hal-05851638",
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  "subjects": [
    {
      "field": "biology",
      "origin": "hal:0.sdv",
      "subfield": "general"
    }
  ],
  "title": "Association of calcium phosphate crystals with pain and inflammation among individuals with advanced knee osteoarthritis: A cross-sectional study.",
  "title_text": "Association of calcium phosphate crystals with pain and inflammation among individuals with advanced knee osteoarthritis: A cross-sectional study.",
  "type": "peer-reviewed",
  "updated_at": "2026-11-06T12:20:44Z",
  "url": "https://research.draconitic.com/paper/b5n19qnq3aghs",
  "venue": "Osteoarthritis and cartilage open",
  "versions": []
}