Rheumatoid synovial may invade the joint capsule, ligaments, and tendons, and it may add to joint instability include by destruction of cartilage and bone.

• 风湿性滑液会进入至膝盖骨，韧带及肌腱，包括损害软组织及骨头，并产生关节不稳。多年后，二类骨质疏松症的变化就会明显了。