Arthritis pain in knees is one of the most common knee problems. Indeed, arthritis is the leading cause of disability in the US, and affects millions of people worldwide.
“Arthritis” simply means “inflammation of the joint”. It is characterised by changes in the bones and cartilage in the knee joint.
Knee arthritis may affect the joint between the thigh and shin bones, or the joint between the kneecap and the front of the knee. In some cases, it will affect both joints.
Here we will start by looking at what is actually going on in the knee with arthritis and the different types. Then as you continue through the arthritis pain in knee section you will find lots of information such as the causes, symptoms, stages and treatment options including exercises, injections, brac
What is Arthritis?
There are two different types caused by either “wear and tear” (osteoarthritis) or inflammation (Rheumatoid Arthritis). Knee arthritis may affect the tibiofemoral joint (knee joint) or the patellofemoral joint (kneecap joint).
The knee joint is made up of three bones, the femur (thigh), tibia (shin) and patella (kneecap). The ends of the bones are covered by thick layers of cartilage.
Cartilage is a thick, spongy material that lines the joint providing lubrication and cushioning, which allows the knee to move smoothly and painlessly. It also works as a shock absorber and ensures that the forces going through the knee during daily activities are spread evenly throughout the joint.
Arthritis pain in knees develops when the cartilage thins and wears away and bony bumps known as spurs develop. This results in bone-on-bone contact which causes pain, stiffness and inflammation.
Types of Arthritis Pain in Knee
There are two main types of arthritis in the knee:
1) Osteoarthritis: where there is degeneration of the bones
2) Rheumatoid Arthritis: where there is inflammation in the joint
1) Osteoarthritis Overview
This is commonly known as “wear and tear” arthritis. Osteoarthritis is by far the most common cause of arthritis pain in knees affecting approximately 16 million people. Usually osteoarthritis of the knee is related to, but not caused by aging, most commonly affecting people over the age of 65. Other common terms used are “degenerative arthritis knee” or “arthrosis”.
In a normal, healthy knee joint, there is a reasonable sized gap between the bones (tibia and femur) due to a thick layer of cartilage and lubricating fluid.
The surface of the bones is nice and smooth and as the knee bends and straightens, the joint moves easily and painlessly due to the cushioning from the cartilage.
With osteoarthritis of the knee, a few things happen. The cartilage thins and as a result the bone underneath begins to thicken and lays down new bone to try and protect itself.
These spurs stick up so the joint surfaces are no longer smooth but are all bumpy. They are known as osteophytes or knee bone spurs.
As a result of these changes, there is less space between the bones. This means that as you use the knee, you can get bone rubbing on bone, causing arthritis pain in knee joints. The bone spurs can also limit the amount of movement in the knee leading to stiffness.
2) Rheumatoid Arthritis
Rheumatoid arthritis is a chronic, systemic inflammatory disorder (chronic = long term, systemic = throughout the body, inflammatory = swelling). It causes inflammation as well as excess fluid in the joints. It often leads to destruction of the cartilage. Joints become swollen, painful and warm, and movement is limited by resultant stiffness.
Rheumatoid arthritis is less common than osteoarthritis and its incidence is actually declining. It affects around 1% of the world’s population and is three times more prevalent in women than men.
Onset usually occurs between the ages of 40-50. It will usually affect a number of joints, especially the hands, feet and neck. Symptoms can come and go, known as “flare ups”. One of the most distinguishing features is morning joint stiffness which eases with movement.
Locations of Knee Arthritis
Knee arthritis can develop at either or both of the joints of the knee:
1) Tibiofemoral Arthritis
This tends to be what people typically think of when they talk about knee arthritis. It affects the tibiofemoral joint with damage to the cartilage lining the bottom of the thigh bone and the top of the shin bone.
Tibiofemoral arthritis pain in knee tends to be felt deep inside the knee joint and tends to be associated with knee stiffness, weakness and swelling.
2) Patellofemoral Arthritis
Here, the arthritis affects the patellofemoral joint, where the kneecap meets the thigh bone. The patella sits in the patellar/trochlear groove on the front of the femur and glides up and down as the knee moves.
In patellofemoral arthritis, there is damage to the cartilage on the back of the kneecap and the cartilage lining the patellar groove. Pain tends to be felt at the front of the knee can is worse with activities such as climbing stairs, getting up from sitting and squatting.