You are here

Article Text

Article menu

Download PDFPDF

Osteoarthritis
Original article
Thickness of the bone-cartilage unit in relation to osteoarthritis severity in the human hip joint
  1. Louise Brøndt Hartlev1,
  2. Rasmus Klose-Jensen1,
  3. Jesper Skovhus Thomsen2,
  4. Jens Randel Nyengaard3,
  5. Lene Warner Thorup Boel4,
  6. Mogens Berg Laursen5,
  7. Trine Bay Laurberg1,
  8. Andreas Wiggers Nielsen1,
  9. Kristian Steengaard-Pedersen1 and
  10. Ellen-Margrethe Hauge1,6
  1. 1 Department of Rheumatology, Aarhus University Hospital, Aarhus, Denmark
  2. 2 Department of Biomedicine – Anatomy, Aarhus University, Aarhus, Denmark
  3. 3 Department of Clinical Medicine,Core Centre for Molecular Morphology, Section for Stereology and Microscopy, Centre for Stochastic Geometry and Advanced Bioimaging, Aarhus University, Aarhus, Denmark
  4. 4 Institute of Forensic Medicine, Aarhus University, Aarhus, Denmark
  5. 5 Orthopaedic Surgery Research Unit, Aalborg Hospital – Aarhus University Hospital, Aalborg, Denmark
  6. 6 Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
  1. Correspondence to Professor Ellen-Margrethe Hauge; ellhau{at}rm.dk

Abstract

Objective Bone formation is a hallmark of osteoarthritis (OA). It has been speculated that bone formation may occur because of ossification at the bone-cartilage unit, that is, bone formation directly involving the calcified cartilage (CC). This study aimed to investigate the thickness of the CC and subchondral bone (SCB) in relation to the severity of the overlying articular cartilage (AC) degeneration.

Design We investigated femoral heads from 20 patients with OA and 15 healthy subjects with design-based stereology using systematic uniform random sampling of the entire joint surface. This was combined with the Osteoarthritis Research Society International (OARSI) OA cartilage histopathology assessment system, thus obtaining focal OARSI grades paired with thickness measurements of AC, CC and the SCB.

Results The patients with OA had thicker CC (mean 159; 95% CI 144 to 177 µm) compared with the healthy subjects (mean 132; 95% CI 113 to 1550 µm; p=0.036), and this difference was even higher in areas without loss of AC thickness (OARSI grade ≤3); 187 (95% CI 164 to 214) µm vs 132 (95% CI 113 to 155) µm (p=0.001). In the patients with OA, a thicker SCB was observed in areas with loss of AC thickness (OARSI grade ≥4), but not in areas without loss of AC thickness (OARSI grade ≤3).

Conclusion The study showed that thicker CC is present in early stages of OA, suggesting that bone formation by endochondral ossification is an early phenomenon of OA. Thickening of the SCB was present, but only in areas with denuded bone. Suggesting that also appositional bone growth occurs and that it may be a consequence of changed biomechanics.

  • osteoarthritis
  • subchondral bone
  • stereology
  • articular cartilage
  • calcified cartilage
  • hip

This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by/4.0

https://doi.org/10.1136/rmdopen-2018-000747

Statistics from Altmetric.com

    Request Permissions

    If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.

    View Full Text

    Footnotes

    • Contributors All authors were involved in drafting the article or revising it critically for important intellectual content, and all authors approved the final version to be published. Study conception and design: LBH, JST, JRN and EMH. Acquisition of tissue: LBH, LWTB, MBL, TBL and EMH. Analysis and interpretation of data: RKJ, LBH, JST, JRN, AWN and EMH.

    • Funding The study has been financially supported by the Danish Council for Independent Research (Medical Science), Danish Rheumatism Association, HN Family Foundation, Kathrine and Vigo Skovgaards Foundation, Henny and Helge Holgersens Grant, Aase and Ejnar Danielsen’s Foundation, Dagmar Marshall’s Foundation, Managing Director Ib Henriksen’s Foundation, Managing Director Jacob Madsen and wife Olga Madsen’s Foundation, the Beckett Foundation, the Gangsted Foundation, Gerda and Aage Haensch’s Foundation, the Hørslev Foundation, the Illum Foundation and the Valdemar Foersom and wife Thyra Foersom’s Foundation. The Centre for Stochastic Geometry and Advanced Bioimaging is supported by Villum Foundation.

    • Competing interests EMH reports personal fees from MSD, Pfizer, UCB and Sobi; grants from Roche and Novartis, outside the submitted work. All other authors have no conflicts of interest to declare.

    • Patient consent Obtained.

    • Ethics approval The Central Denmark Region Committees on Health Research Ethics (J number 10776).

    • Provenance and peer review Not commissioned; externally peer reviewed.

    • Data sharing statement No additional data are available.