Arthritis mainly affects the joints where two bones meet, but it can also involve nearby tissues like cartilage, bone, ligaments, tendons, and sometimes even organs in certain types.

Main places arthritis hits

  • Weight‑bearing joints : knees, hips, spine (neck and lower back) are very common sites, especially for osteoarthritis.
  • Hands and wrists : small joints in the fingers, thumbs, and wrists are often affected, particularly in rheumatoid arthritis and osteoarthritis.
  • Feet and ankles : toe joints (including the big toe) and ankles can become painful and stiff.
  • Shoulders and elbows : less common than knees or hands but still frequently involved, especially in inflammatory types like rheumatoid arthritis.
  • Hips : a major site for both osteoarthritis and inflammatory arthritis, often causing groin, buttock, or thigh pain.

What “inside the body” it affects

  • Joint cartilage : the smooth cushioning at the ends of bones wears down or becomes inflamed, leading to pain, stiffness, and grinding.
  • Bone : as cartilage is lost, bones can rub together, form bone spurs (osteophytes), and change shape.
  • Joint lining (synovium) : in inflammatory arthritis (like rheumatoid arthritis), the inner lining becomes thick and inflamed, damaging cartilage and bone.
  • Ligaments and tendons : the soft tissues supporting the joint can weaken, stretch, or become inflamed, causing instability and pain.
  • Muscles around the joint : pain and reduced use can lead to muscle weakness and wasting.

When arthritis affects more than joints

Some types of arthritis are part of broader autoimmune or inflammatory diseases and can affect organs as well as joints.

  • Rheumatoid arthritis can involve eyes, lungs, heart, blood vessels, and skin, not just hand and foot joints.
  • Spondyloarthritis (including ankylosing spondylitis and psoriatic arthritis) can affect the spine, pelvis, eyes, and skin.
  • Reactive arthritis may involve joints, eyes, urinary tract, and sometimes skin after an infection.

Simple takeaway

  • Arthritis is a problem of joints , but those joints can be almost anywhere in the body.
  • Most commonly, it targets knees, hips, hands, feet, and the spine, and in some forms it can reach beyond joints to affect organs as well.

Information gathered from public forums or data available on the internet and portrayed here.