Association of calcium phosphate crystals with pain and inflammation among individuals with advanced knee osteoarthritis: A cross-sectional study.
9 affiliations
- 1The Parker Institute, Copenhagen University Hospital - Bispebjerg & Frederiksberg, Copenhagen, Denmark.
- 2Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark.
- 3Department of Orthopaedic Surgery, Copenhagen University Hospital - Amager & Hvidovre, Copenhagen, Denmark.
- 4Department of Orthopaedic Surgery and Traumatology, Copenhagen University Hospital - Bispebjerg and Frederiksberg, Copenhagen, Denmark.
- 5Department of Radiology, Copenhagen University Hospital - Bispebjerg & Frederiksberg, Copenhagen, Denmark.
- 6Research Unit of Rheumatology, Department of Clinical Research, University of Southern Denmark, Odense University Hospital, Odense, Denmark.
- 7Centre for General Practice, Department of Public Health, University of Copenhagen, Copenhagen, Denmark.
- 8Univ. Lille, CHU Lille, Univ. Littoral Côte D'Opale, ULR 4490 - MABLab- Adiposité Médullaire et Os, Lille, F-59000, France.
- 9Dept. of Rheumatology, Hôpital Saint-Philibert, Université Catholique de Lille, Lille, France.
Abstract
Background
Basic 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
SF 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
Fifty-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
BCP and CPP positivity in SF was neither associated with knee OA patients' symptoms nor US-detected inflammation.
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BibTeX
@article{poulsen2026association,
title = {{Association of calcium phosphate crystals with pain and inflammation among individuals with advanced knee osteoarthritis: A cross-sectional study.}},
author = {Asbjørn Seenithamby Poulsen and Kristine Ifigenia Bunyoz and Saber Muthanna Aljuboori and Camilla Toft Nielsen and Anna Døssing and Karen Ellegaard and Tobias Haugegaard and Henrik Gudbergsen and Robin Christensen and Guillaume Falgayrac and Tristan Pascart and Marius Henriksen and Henning Bliddal},
journal = {Osteoarthritis and cartilage open},
year = {2026},
month = oct,
doi = {10.1016/j.ocarto.2026.100887},
url = {https://europepmc.org/article/MED/42927365},
note = {CC BY-NC-ND},
}
RIS
TY - JOUR
TI - Association of calcium phosphate crystals with pain and inflammation among individuals with advanced knee osteoarthritis: A cross-sectional study.
AU - Asbjørn Seenithamby Poulsen
AU - Kristine Ifigenia Bunyoz
AU - Saber Muthanna Aljuboori
AU - Camilla Toft Nielsen
AU - Anna Døssing
AU - Karen Ellegaard
AU - Tobias Haugegaard
AU - Henrik Gudbergsen
AU - Robin Christensen
AU - Guillaume Falgayrac
AU - Tristan Pascart
AU - Marius Henriksen
AU - Henning Bliddal
PY - 2026
DA - 2026/10/12
JO - Osteoarthritis and cartilage open
DO - 10.1016/j.ocarto.2026.100887
UR - https://europepmc.org/article/MED/42927365
AB - Background Basic 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 SF 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 Fifty-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 BCP and CPP positivity in SF was neither associated with knee OA patients' symptoms nor US-detected inflammation.
SN - 2665-9131
ER -