Knee pain is a really common problem. It can be caused by several different things. Because you use the knee joint all day, it can make it very difficult to perform everyday tasks when in pain.
The knee joint is the largest joint in the body. It is vulnerable to injury as it bears an enormous amount of pressure while providing flexible movement. When we walk, the load on our knees is equal to 1.5 times our body weight. When climbing stairs it is equal to 3-4 times our body weight. When we squat, the load on our knees increases to about 8 times our body weight.
But this weight bearing does not mean its bad for the knee. Studies suggest that exercise that load the knee joint can actually help with development of synovial fluid (fluid in the joint) and enhances cartilage performance.
To have a better understanding of the causes of pain in the knee joint it would probably be best to start with some information about the knee and what makes the knee joint. The knee joint is made up of 4 bones, the patellar (knee cap), the femur (thigh bone), the Tibia (shin bone) and a bone that runs parallel to it called the Fibula.
The knee is actually made from 3 joints and not just one joint that most people would think. Where the Tibia meets the Femur is one of them and is the main joint of the knee however, where the Fibula meets the Tibia is also another joint and that’s found slightly below the Tibiofemoral joint but more towards the outside of the knee.
The third joint is the patellofemoral joint, where the kneecap (or patella) meets the femur. Let’s not forget about cartilage, ligaments, menisci, and tendons as well.
Learn more about joints specifically by clicking this article.
Menisci – Why It’s Important
So as you probably know, the cartilage sits between the two bones of the knee so the bones themselves don’t actually meet but It lets the bones rub or pass smoothly over one another as the knee bends and straightens.
This cartilage can be compressed from 5-20% of its thickness however, when the cartilage starts to go through a process called disrepair this is when the joint starts getting signs of Osteoarthritis which we will speak a little about later.
There is a tissue that I mentioned earlier called the menisci, this is a very important tissue for shock absorbing, mobility and stability of the knee. The menisci is found between the joint of the tibia and the femur, each knee has 2 of them that are C shaped that point towards each other like this C Ↄ.
Forcefully twisting or rotating your knee, especially when putting your full weight on it, can lead to a torn meniscus. A tear in the meniscus causes pain, swelling and stiffness. You might also feel a locking or a clicking and have trouble extending your knee fully.
The 4 Ligaments Of Each Knee
- Anterior cruciate ligament (ACL). This ligament is located in the center of the knee and controls rotation and stabilises forward movement of the tibia (shin bone).
- Posterior cruciate ligament (PCL). This ligament is located in the back of the knee and stabilises backward movement of the tibia.
A torn or ruptured ACL is one of the most common ligament injuries. This usually occurs due to sudden twisting motions like pivoting (when the foot is planted, but the knees turn the other way).
Skiing, basketball, and football are sports that have an increased risk of ACL injuries. Females are also more likely to injure their ACL due to instability issues of the knee.
The PCL is also a common ligament to tear or rupture in the knee. However, a torn or ruptured PCL usually occurs with sudden, direct impact, such as in a car accident or during a football tackle that pushes the tibia backwards forcefully.
- Medial collateral ligament (MCL). This ligament gives stability to the inner knee and is located on the inside of the knee between the tibia and the femur.
- Lateral collateral ligament (LCL). This ligament gives stability to the outer knee and is located on the outside of the knee between the tibia and the femur.
The MCL is more likely to be injured than the LCL. Stretch and tear injuries to the collateral ligaments are usually caused by impact to the outer side of the knee. When the MCL is torn it’s usually accompanied by a meniscus tear or an ACL tear as these fibres are interconnected.
There are many tendons that connect muscles to the bones of the knee, These tough bands of soft tissue provide stability to the joint. They are similar to ligaments, but instead of connecting bone to bone, they connect bone to muscle.
The largest tendon in the knee is the patellar tendon, which runs over the kneecap, up the front of the thigh, and attaches to the quadriceps. This tendon is a common sight for injury due to the increased amount of strain over the knee and maltracking of the Patella, and there are multiple sites around the knee that can become affected due to tendon inflammation or strain.
Knee bursitis is inflammation of a small fluid-filled sac (bursa) situated around your knee joint. Bursae job is to reduce friction and reduce pressure between your bones and tendons, muscles and skin near your joints.
They function as smooth surfaces to reduce friction of body tissues. Any of the bursa in your knee can become inflamed, but bursitis of the knee commonly occurs over the kneecap or on the inner side of your knee below the joint.
Types of Arthritis
- Steoarthritis. Also known as degenerative arthritis, osteoarthritis is the most common type of arthritis this is due to a disrepair condition that occurs when the cartilage in your knee does not repair after is has been damaged with overuse and age.
- Rheumatoid arthritis. Probably the most taxing form of arthritis, rheumatoid arthritis is an autoimmune disease that can affect almost any joint in your body. Although rheumatoid arthritis is a chronic disease, it tends to affect joints on both sides of the body at the same time and may even come and go.
- Gout. This occurs when uric acid crystals build up in the small arteries of the joint. While gout most commonly affects the big toe, it can also occur in the knee and even the ear.
- Pseudogout. Often mistaken for gout, pseudogout is caused by calcium-containing crystals that develop in the joint fluid. Knees are the most common joint affected by pseudogout.
- Septic arthritis. Sometimes your knee joint can become infected, leading to swelling, pain and redness. Although these symptoms can occur in the other types of Arthritis, when there’s an infection it’s normally a lot more severe and can be accompanied by a fever, fatigue, nausea and there’s usually no trauma before the onset of pain.
There are many other issues that can cause knee pain; however, this article is to describe some of the most common causes. I hope this helps you understand a bit more about the knee and what we as Osteopaths look out for.
Watch Dan explain more about the knee via the following link: https://www.youtube.com/watch?v=sedpabTBS7o