ab2005

Subtyping of osteoarthritic synoviopathy

S. Oehler¹, D. Neureiter¹, C. Meyer-Scholten², T. Aigner¹

¹Department of Pathology, University of Erlangen-Nürnberg, Erlangen; ²Zentrum für Rheumapathologie (WHO-Center), University of Mainz, Mainz, FRG.

ABSTRACT
Objective
Osteoarthritis research is traditionally concentrating on events within the degenerated articular cartilage. Changes in the synovial membrane are largely neglected. In fact, they are generally interpreted as secondary to the cartilage changes and not pathogenetically involved in the disease process. In this study, we present a systematic analysis of the synovial reaction pattern in early and late stages of the osteoarthritic disease process.

Methods
A large series of synovial specimens derived from early and late stage osteoarthritic cartilage disease were investigated by histological and immunohistochemical means for tissue architecture and inflammatory cell infiltrates. For comparison, also samples with rheumatoid arthritis, seronegative arthritis, and septic arthritis were included as well as normal synovial membrane specimens.

Results
In all specimens derived from patients with diagnosed osteoarthritis alterations of the synovial tissue were observed. A large spectrum of alterations was found in different stages of osteoarthritic joint disease and four different basic pattern of synovial reactions could be identified: (i) hyperplastic, (ii) inflammatory, (iii) fibrotic, and (iv) detritus-rich synoviopathy.

Conclusion
We show that in all cases of clinically ouvert osteoarthritic joint disease significant synovial pathology is associated. Furthermore, our study clearly documents that in osteoarthritic synovium significant inflammation can occur. This is suggestive of a distinct pathogenetic role of the synovium also in osteoarthritic cartilage degeneration at least in a subset of cases.

Key words
Inflammation, synovia, osteoarthritis.

This work was supported by the IZKF-Erlangen (grant B16).
Please address correspondence and reprint requests to: Thomas Aigner, MD, Cartilage Research, Department of Pathology, University of Erlangen-Nürnberg, Krankenhausstr. 8-10, D-91054 Erlangen, FRG.
E-mail: thomas.aigner@patho.imed.uni-erlangen.de