Our knees… we take them for granted until they start hurting. This article provides some general information about knee problems including a description and diagram of the different parts of the knee, including bones, cartilage, muscles, ligaments, and tendons. Most importantly, some general information is also provided on the prevention of knee problems.
What Causes Knee Problems?
Some knee problems, such as osteoarthritis, result from wear and tear of parts of the knee. Other problems result from injury, such as a blow to the knee or sudden movements that strain the knee ligaments beyond their normal range of movement. The knee joint works like a hinge to bend and straighten the lower leg. It permits a person to sit, stand, and pivot. The knee is composed of the following parts:
Bones and Cartilage
The knee joint is the junction of three bones: the femur (thigh bone or upper leg bone), the tibia (shin bone or larger bone of the lower leg), and the patella (kneecap). The patella is about 2 to 3 inches wide and 3 to 4 inches long. It sits over the other bones at the front of the knee joint and slides when the leg moves. It protects the knee and gives leverage to muscles.The ends of the three bones in the knee joint are covered with articular cartilage, a tough, elastic material that helps absorb shock and allows the knee joint to move smoothly. Separating the bones of the knee are pads of connective tissue called menisci, which are divided into two crescent-shaped discs positioned between the tibia and femur on the outer and inner sides of each knee. The two menisci in each knee act as shock absorbers, cushioning the lower part of the leg from the weight of the rest of the body, as well as enhancing stability.
There are two groups of muscles at the knee. The quadriceps muscle comprises four muscles on the front of the thigh that work to straighten the leg from a bent position. The hamstring muscles, which bend the leg at the knee, run along the back of the thigh from the hip to just below the knee.
Ligaments are strong, elastic bands of tissue that connect bone to bone. They provide strength and stability to the joint. Four ligaments connect the femur and tibia:
- The medial collateral ligament (MCL) provides stability to the inner (medial) aspect of the knee.
- The lateral collateral ligament (LCL) provides stability to the outer (lateral) aspect of the knee.
- The anterior cruciate ligament (ACL), in the center of the knee, limits rotation and the forward movement of the tibia.
- The posterior cruciate ligament (PCL), also in the center of the knee, limits backward movement of the tibia.
Other ligaments are part of the knee capsule, which is a protective, fiber-like structure that wraps around the knee joint. Inside the capsule, the joint is lined with a thin, soft tissue, called synovium.
Tendons are tough cords of tissue that connect muscle to bone. In the knee, the quadriceps tendon connects the quadriceps muscle to the patella and provides power to extend the leg. The patellar tendon connects the patella to the tibia.
How Can People Prevent Knee Problems?
Some knee problems, such as those resulting from an accident, cannot be foreseen or prevented. However, a person can prevent many knee problems by following these suggestions:
- Warm up by walking or riding a stationary bicycle, then do stretches before exercising or participating in sports. Stretching the quadriceps muscles in the front of the thigh and the hamstrings in the back of the thigh reduces tension on the tendons and relieves pressure on the knee during activity.
- Strengthen the leg muscles. Doing specific exercises such as walking up stairs or hills, or riding a stationary bicycle, can provide a strength stimulus to de-conditioned legs. However, a supervised workout with weights is the best pathway to strengthening leg muscles that benefit the knee.
- Avoid sudden changes in the intensity of exercise. Increase the force or duration of activity gradually.
- Wear shoes that fit properly and are in good condition to help maintain balance and leg alignment when walking or running. Knee problems may be caused by flat or over-pronated feet (feet that roll inward) and by feet that are over-supinated (feet that roll outward). People can often reduce some of these problems by wearing special shoe inserts called orthotics available from a podiatrist. Maintain appropriate weight to reduce stress on the knee. Obesity increases the risk of degenerative conditions such as osteoarthritis of the knee.
Do I Need Any Tests?
Sometimes, tests may be ordered to help diagnose your knee problem. These tests may include x-rays, ultrasound studies, CT scans, MRI scans and blood tests. Your Sports Medicine Specialist, Orthopaedic Surgeon or Family Doctor will advise you on the necessity of these tests.
What Kinds of Health Professionals Treat Knee Problems?
Knee injuries can be assessed by your Sports Medicine Specialist, Orthopaedic Surgeon, Physiotherapist or Family Doctor. Any knee pain that lasts longer than 7-10 days in spite of rest from offending activities, combined with icing and stretching, should be investigated by a health care professionals.