Knees are often discussed in the elementary classroom as examples of hinges or levers; however, the knee joint is definitely more complex than that. The joint is also:
- Load bearing. Between the two knees, they hold 90% of your body’s weight
- Capable of a torsional, or twisting motion
Unlike a door-hinge, the knee joint is made from more moving parts than most people realize. Understanding the anatomy of the knee is a great way to keep these joints healthy and pain-free.
Within the knee, two large bones and a small bone meet in your knee. Within the joint, the top portion of the shinbone (the tibia) contacts the bottom end of the thighbone (the femur). The small bone is the kneecap or patella, which rests against a groove at the end of the femur. This groove holds the kneecap somewhat in place while allowing it the ability to move around.
At the end of each of the bones, is a protective coating of slippery, tough tissue called cartilage. The cartilage acts as lubricant to keep the joint moving smoothly. Spongy disks of tissue called menisci minimize the energy that travels up the legs when you walk or run. Additionally, numerous bursae, or fluid-filled sacs, help the knee move smoothly.
Problems that can affect these tissues include:
- Osteoarthritis. This is a condition that causes the protective cartilage to grow thin and rough. Less lubricating cartilage leaves the joints with less protection. The bones can become damaged, and everyday movements will cause knee pain and further damage.
- Meniscal tears. This is a condition which turning the knee joint the wrong way while applying force will tear the menisci. The tear can cause any degree of knee pain and may cause your knee to get “stuck” while it is in motion.
In addition to the confluence of bones, cartilage, and menisci, several other soft tissues are also attached around the knee:
- Tendon: A tendon attaches your quadriceps muscles to your kneecap and four ligaments.
- Ligaments: Four ligaments attach the femur and tibia to each other. There is one at either side of the knee and one each to the front and back of the joint.
Problems that can affect these structures include:
- Ligament issues: Direct trauma or shifting directions too quickly (as athletes may) can tear knee ligaments. Depending on which ligament is injured, you may experience pain and instability in the joint or trouble walking, standing or bending.
- Tendon issues: Repeat motions can cause knee tendons to become painfully inflamed. In addition, the tendon is capable of tearing if it undergoes enough trauma. Both types of injuries result in pain and possible immobility.
- Iliotibial band syndrome: The iliotibial band is a strip of thick tissue that runs down the outside of the thigh and attaches near the knee. Through activities like running, the band rubs quickly over the kneecap and can become inflamed. This typically only causes pain on the outside of the knee during or after the activity.
Any type of knee pain that is either frequent or acute is definitely cause to see your health care team. The doctor will work to pinpoint and treat any one of the structures in the knee in order to prevent further damage.