Almost everyone has experienced a minor knee difficulty at some time or another. More often than not our bodily actions don't create problems, but it's unsurprising that symptoms develop from day-to-day deterioration, excessive use, or injuries. Knee issues and traumas generally take place in the course of sporting activities or leisure activities, work-related duties, or household tasks.
The knee is the biggest joint in the entire body. The top and lower bones of the knee are separated by two discs (menisci). The top leg bone (femur) and the lower leg bones (tibia and fibula) are linked by ligaments, tendons, and muscles. The surface of the bones within the knee joint is protected by articular cartilage, which absorbs shock and gives a sleek, sliding surface for joint mobility. See an illustration of the components of the knee. Although knee problems are often the result of an injury to one or more of these structures, they may have other causes. Some people are more prone to get knee problems than others. There are many factors that can increase the likelihood of knee injuries. Age, activity level, sporting activities and other medical conditions can play a role.
Sudden (acute) injuries
Knee problems are mostly caused by injuries. Acute (sudden) injuries may be caused by a blow to the knee or from abnormal twisting, or bending the knee, or falling on the knee. Pain, bruising, or swelling can be severe and develop within minutes of the injury. Nerves or blood vessels may be nipped or damaged due to the injury. The knee or lower leg may feel weak, numb, or cold; It might tingle, or look blue or pale. Acute injuries include:
- Strains, sprains, or other injuries to the tendons and ligaments that connect and support the kneecap.
- Tears in the rubbery cushions of the meniscus (knee joint).
- Tears in the ligaments. The most commonly injured ligament of the knee is the medial collateral ligament (MCL).
- Fractures of the kneecap, lower part of the femur, or upper part of the tibia or fibula. Knee fractures are most often caused by an abnormal force, such as falling on your knee, a severe twisting motion, or any severe force that bends the knee, or if your knee hits an object with great force.
- Dislocation of the kneecap. This occurs most frequently in 13 to 18-year-old girls. Bits of bone or tissue from fractures or dislocations may get trapped in the joint and get in the way of movement.
- Dislocation of the knee joint. This is a rare injury that would only come from great force. It is a serious injury and would require immediate medical care.
Injuries arising from Overuse
Overuse injuries happen with repetitive activities or prolonged or repeated pressure on the knee. Activities like climbing stairs, jogging, bicycle riding, or jumping stress joints and other tissues and can lead to inflammation and irritation. Overuse injuries include:
- Bursitis, which is inflammation of the small sacs of fluid that cushion and lubricate the knee.
- Tendinitis, which is inflammation of the tendons or small tears in the tendons (tendinosis).
- Plica syndrome, which is thickening or folding of the knee ligaments.
- Patellofemoral pain syndrome, which is pain in the front of the knee from injury, overuse, excess weight, or problems in the kneecap.
- Iliotibial band syndrome, which is irritation and inflammation of the band of fibrous tissue that runs down the outside of the thigh.