How does osteoarthritis progress?

The breakdown of cartilage that leads to osteoarthritis (OA) does not occur overnight, even though that first sharp pain in your knee might make it seem to come on all of a sudden. No, this erosion almost always happens slowly.

• Sometimes, the pain and stiffness that accompany the disintegrating cartilage appears so gradually that people ignore it or chalk it up to "getting older."
• And for many lucky people, this is as far as their osteoarthritis ever progresses: In those cases it remains a only mild problem; causing symptoms they're barely aware of.
• When cartilage continues to erode, however, the increasingly bothersome symptoms send many people to the doctor's office.
• After exercise, knees and other joints may ache or feel stiff for a brief time. You may also feel stiff after you've been sitting for awhile — for example, when climbing out of the car after a long ride or getting up after watching a movie.

• Eventually, cartilage wears away to the point that, in some areas, the bones rub up against one another.
• People may feel their knees lock briefly as they climb the stairs, or they might experience a grinding sensation — or even hear a grinding sound — when they bend affected knees or hips.
• People may also find themselves avoiding once-routine activities because of the pain — the daily walk to the newsstand, for example, or working in the garden on weekends.
• If the affected joint is a hip or knee, people may begin to limp as they try to minimize the pain.
• Furthermore, small chunks of fragmented cartilage floating in the synovial fluid may begin to irritate the synovial membrane and add to the discomfort.
• In response, the membrane becomes inflamed and produces excess fluid, which makes the joint swell.
• In addition to pain, a person may now notice that the joint's range of motion is becoming restricted.

• OA becomes more severe as changes extend beyond cartilage to the underlying bones, which may sprout small growths (known as bone spurs or osteophytes) around their outer edges.
• Bone spurs increase the joint's surface area and may be the bones' defensive reaction to the extra pressure created when their protective covering has worn away.
• Unfortunately, bone spurs often make things worse: Spurs on the spine, for example, may cause severe pain by pinching the nerves connecting the spinal cord to the muscles; sharp spurs around the rim of the knee joint may worsen the pain and tenderness.
• By this time, people may find that arthritis pain is keeping them awake at night.When the cartilage is completely eroded, the sensitive bones rub against each other within the joint.
• At this point, the pain can be excruciating and nearly unrelenting even after the slightest movement. When such severe osteoarthritis affects weight-bearing joints — like the knees or the hips — it can be crippling, especially if:
• Uneven cartilage loss has created uneven joint surfaces, causing bones to become misaligned, leading to instability in the joint itself.
• Extensive bone-spur formation limits the affected joint's mobility.
• The muscles and tendons that support the joint have shortened and weakened due to disuse, leading to muscle spasms and even more disability. Today's joint-replacement operations can be a godsend for people with such severe osteoarthritis.