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Updated: Aug 16, 2026
Standardized Histomorphometric Evaluation of Osteoarthritis in a Surgical Mouse Model
Published on: May 6, 2020
Presence of pannus-like tissue on osteoarthritic cartilage and its histological character
A Shibakawa1, H Aoki, K Masuko-Hongo
1Department of Bioregulation, Institute of Medical Science, St Marianna University School of Medicine, Kawasaki, Kanagawa, Japan.
Objective:
To investigate and characterize pannus-like tissue which is often present on osteoarthritic articular cartilage.
Design:
Cartilage specimens from 15 knee and five hip joints of patients with osteoarthritis (OA) undergoing arthroplasty were stained for HE and Safranin-O. They were also immunostained by antitype I collagen, type II collagen, CD68, IL-1beta and MMP3 antibodies.
Results:
Ninety percent of joints have pannus-like tissue on the articular surface, preferentially in a marginal area. The articular cartilage was divided into three regions according to the location: the marginal zone, the intermediate zone and the paraeburnated zone. Pannuslike tissue in OA knee joint occurred 45.9%, 27.5% and 11.1% of the surface of each region respectively. Histologically, pannus-like tissue could be classified into the vascular type and the fibrous type. Extracellular matrix of both types of tissues were negative for Safranin-O and type II collagen, but positive for type I collagen. IL-1beta and MMP3 expressing cells are predominant in pannus-like tissue, whereas CD68 positive cells were infiltrated in only a few samples. Vascular type tissue kept continuity with bone marrow suggesting mesenchymal origin.
Conclusion:
Pannus-like tissue exists in advanced OA cartilage, preferentially in the marginal zone. It expressed IL-1beta and MMP3, which strongly suggests that it contributes to cartilage degradation.
