11.7 · Joint disorders: Inflammatory arthritis, RA & ankylosing spondylitis

Inflammatory joint disease

Inflammatory damage in the synovial membrane or articular cartilage with systemic signs of inflammation

Systemic signs of inflammatory joint disease

Fever, leukocytosis, malaise, and anorexia

Infectious inflammatory joint disease

Caused by introduction of pathogens through a wound or the bloodstream

Noninfectious inflammatory joint disease

Caused by immune reactions such as rheumatoid arthritis and ankylosing spondylitis, or deposition of monosodium urate crystals in gouty arthritis

Rheumatoid arthritis

Chronic, systemic, inflammatory autoimmune disease distinguished by joint swelling and tenderness and destruction of synovial joints

First tissue affected in rheumatoid arthritis

Synovial membrane, followed by articular cartilage, joint capsule, and surrounding tissue

Joints affected in rheumatoid arthritis

Fingers, wrists, elbows, feet, ankles, and knees, symmetrically

Cause of rheumatoid arthritis

Unknown, but probably interaction of genetic factors with inflammatory mediators

Rheumatoid factors

Autoantibodies produced through an antigen-induced T cell mediated mechanism

Rheumatoid factor mechanism

RFs form complexes with IgG that deposit in the synovial membrane and activate complement protein

Pathogenesis of joint destruction in RA

Inflammatory cytokines such as TNF and IL1 are generated, vasodilation and increased vascular permeability cause edema, and neutrophils and macrophages release lysosomal enzymes causing tissue destruction

Pannus

Characteristic vascular granulation tissue containing lymphocytes, macrophages, fibroblasts, and mast cells

Why pannus matters

It grows over and erodes articular cartilage and bone, destroying the joint, and is the key diagnostic feature differentiating RA from OA

Rheumatoid arthritis clinical manifestations

Begins with systemic inflammation of fever, fatigue, and weakness, with painful, tender, stiff joints starting in the hands and wrists

Rheumatoid arthritis stiffness pattern

Lasts about 1 hour after rising

Rheumatoid arthritis deformity example

Ulnar deviation of the hands

Muscle effect in rheumatoid arthritis

Loss of mobility leads to atrophy of surrounding muscles

Ankylosing spondylitis

Chronic systemic inflammatory disease of the joints of the vertebral column, beginning with the sacroiliac joints then ascending to smaller spinal joints

Ankylosing spondylitis hallmark

Excessive bone formation at the joint leading to fusion of the joint

Ankylosing spondylitis demographics

Primarily men, starting at 15-40 years old

Ankylosing spondylitis progression

Fibrocartilage discs become inflamed, macrophages and lymphocytes cause damage, fibroblasts secrete collagen that ossifies, and joints fuse