The Three bones that comprise the knee joint are the Femur (Thigh Bone), the Tibia (Shin Bone), and the Patella (Knee Cap). The knee may be described as a modified Hinge joint, similar to the hinge on a door. However, the knee not only bends back and forth like a hinge, it has complex rotational component that occurs with bending and straightening of the knee joint.
Your knee is one of the largest joints in the body and also one of the most complicated. It needs to be strong enough to take our weight and must lock into position so we can stand upright. But it also has to act as a hinge so we can walk, and it must withstand extreme stresses, twists and turns, such as when we run or play sports.
Cartilage is the material inside the joint that provides shock absorption to the knee during weight bearing activities such as walking or stair climbing.
What Is Osteoarthritis?
Osteoarthritis, commonly known as wear-and-tear arthritis, is a condition in which the natural cushioning between joints -- cartilage -- wears away. When this happens, the bones of the joints rub more closely against one another with less of the shock-absorbing benefits of cartilage. The rubbing results in pain, swelling, stiffness, decreased ability to move and, sometimes, the formation of bone spurs.
Osteoarthritis is the most common type of arthritis. While it can occur even in young people, the chance of developing osteoarthritis rises after age 45. According to the Arthritis Foundation, more than 27 million people in the U.S. have osteoarthritis, with the knee being one of the most commonly affected areas. Women are more likely to have osteoarthritis than men.
What happens to a knee with osteoarthritis?
When your knee has osteoarthritis its surfaces become damaged and it doesn’t move as well as it should do. The following happens:
The cartilage becomes rough and thin – this can happen over the main surface of your knee joint and in the cartilage underneath your kneecap.
The bone underneath the cartilage reacts by growing thicker and becoming broader.
The bone at the edge of your joint grows outwards, forming bony spurs called osteophytes.
The synovium may swell and produce extra fluid, causing the joint to swell – this is called an effusion or sometimes water on the knee.
The capsule and ligaments slowly thicken and contract.
Common Causes of Knee Pain and Loss of Mobility
The most common cause of chronic knee pain and disability is Arthritis.
Osteoarthritis usually occurs after age 50. The articular cartilage covering & cushioning the bones of the knee softens & wears away. The bones then rub against each other, causing knee pain and stiffness.
Rheumatoid Arthritis is a disease in which the synovial membrane becomes thickened & inflamed, that results in erosion of the articular cartilage and subsequent damage to the knee joint surface.
Traumatic Arthritis can follow a serious knee injury like fracture or ligament tear. This damages the cartilage leading to arthritis.
What Are the Symptoms of Knee Osteoarthritis?
Symptoms of osteoarthritis of the knee may include:
Pain that increases when you are active, but gets a little better with rest swelling
Feeling of warmth in the joint
Stiffness in the knee, especially in the morning or when you have been sitting for a while • decrease in mobility of the knee, making it difficult to get in and out of chairs or cars, use the stairs, or walk.
Creaking, crackly sound that is heard when the knee moves
While age is a major risk factor for osteoarthritis of the knee, young people can get it, too. For some individuals, it may be hereditary. For others, osteoarthritis of the knee can result from injury or infection or even from being overweight. Here are answers to your questions about knee osteoarthritis, including how it's treated and what you can do at home to ease the pain.
Who Needs Knee Replacment ?
It may be time to have knee replacement surgery if you have:
Severe knee pain that limits your everyday activities
Moderate or severe knee pain while resting, day or night
Long-lasting knee inflammation and swelling that doesn’t get better with rest or medications