Learn what osteoarthritis is and what causes it, explained clearly by Mr. Barkatali, specialist knee surgeon at The Knee Clinic Manchester. Get the facts to better manage your knee health.
For expert knee care, visit https://www.thekneeclinicmanchester.com/
00:00So osteoarthritis forms part of a bunch of conditions called degenerative joint disease.
00:19Osteoarthritis is not the only pathology that causes joints to become degenerate.
00:24Joints can become degenerate following trauma or inflammatory disease such as rheumatoid arthritis.
00:29But osteoarthritis is the most common cause.
00:31So what is osteoarthritis?
00:33Now osteoarthritis affects around one in five people over the age of 45.
00:38And because of osteoarthritis more than 80,000 knee replacements are performed each year.
00:43The knee is composed of the femur and the tibia.
00:47These are two bones.
00:49There is the patella which is a small sesamoid bone which is encased in the quads tendon and the patella tendon.
00:55And the patella articulates with the front of the femur in an area called the trochlea.
01:02The joint is moved by muscles and tendons and is stabilized by ligaments.
01:07So the medial collateral ligament, the lateral collateral ligament and internally it has the ACL and PCL ligaments.
01:14The inside of the joint where the movement takes place is covered in a substance called cartilage.
01:21Then inside the knee joint, for example, this is highline cartilage.
01:25And this is quite amazing stuff because you're born with it.
01:30You can't regenerate it.
01:32The highline cartilage doesn't have a blood supply or a nerve supply.
01:36So whatever you're born with and as an adult, that's what you have for the rest of your life.
01:40So it's important to look after it.
01:41But unfortunately, in a lot of situations, the cartilage can break down.
01:46For example, osteoarthritis.
01:47Now, osteoarthritis is a condition which is characterized by an imbalance in the enzymes that exist within the cartilage that produce the substance of the cartilage, which is called the matrix.
02:00In osteoarthritis, some of these enzymes, the NMPs or matrix metalloproteinases, they're known as, are working too hard.
02:10So that causes an imbalance in the homeostasis or the balance of the cartilage.
02:14And over time, the matrix starts to break down because these enzymes are working too hard.
02:20And that results in a thinning of the cartilage that covers the end of the bone.
02:24So the depth of this cartilage in a healthy joint is around 5 to 8 millimeters in the knee.
02:32And over time, this thins out.
02:34And underlying this cartilage is the bone, where there are some nerve endings.
02:39So what the cartilage does is it allows smooth gliding of the knee joint with every step that you take in every day of your life.
02:47And when you go for a jog or for a run or you play any sport, all of these structures are coming under a lot of strain.
02:53And the cartilage is able to withstand the forces of your body weight during all these kinds of movements and sports, which is quite amazing.
03:02Osteoarthritis doesn't just affect the cartilage.
03:04It affects all the tissues around the joint.
03:06So this structure here is the meniscus, and we can talk more about that later.
03:12So the meniscus is affected and can become degenerate as part of osteoarthritis.
03:16The tendons and the ligaments and the lining of the joint are all affected, and this results in increasing pain, a reduced range of movement, night pain, and just a loss of function of the joint as the osteoarthritis becomes more and more severe.
03:32There are different grades of osteoarthritis, so in the grade 1 osteoarthritis, you don't really notice a change radiographically, as in on the x-rays, and it goes up all the way to grade 4.
03:44So grade 1 is a softening.
03:46Grade 2 is a fissuring of the cartilage.
03:49Grade 3 is a thinning, but there is some cartilage remaining.
03:52And grade 4 is a complete loss of the cartilage in a particular area of the knee joint.
03:58The medial side of the joint is usually most affected, but in severe arthritis, the medial compartment, the lateral compartment, as well as the patellofemoral compartment are degenerate.
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