Some morphological substrates in the pathogenesis of arthritis.

Abstract

In order to gain more insight into pathogeneses of joint diseases like Rheumatoid Arthritis (RA) and possibly also Osteoarthritis (OA), High Resolution Magnetic Resonance Imaging (HR-MRI) of the adult proximal interphalangeal (PIP)-joint in an otherwise normal anatomical specimen of the finger was analyzed. We also investigated the histology of a part of the PIP-joint capsule. In adult proximal interphalangeal joints, dorsal and palmar but also ulnar and radial synovial folds (also described as "fat pads" in other synovial joints) do persist, as our HR-MRI slices reveal. Such synovial folds (e.g., after micro-damage) may elicit chronic inflammatory processes that eventually lead to arthritis. In PIP collateral ligaments, we found neurofilaments and oval-shaped lamellated corpuscles (ø ≈ 120 μ). Supposedly acting as mechanoreceptors in finger motion, they may also produce cytokines and substance P, a neuropeptide involved in pain. These organs may also play a role in the pathogeneses of joint inflammation.