Knees support the body, enable mobility, and play a supporting role in prayers and marriage proposals. This hard-working hinge is a compound joint made up of two long bones, the femur and the tibia, and the flat shield-like patella, or kneecap, which covers and protects the space where the femur and tibia meet. The knee's heavy workload can go unnoticed until an injury interrupts its normal functioning. Knee injuries can be painful and debilitating.
Bursitis
Bursae are little fluid filled pouches that protect the outside of the knee and allow ligaments and tendons to slide freely over the knee joint. Bursitis occurs when bursae become inflamed by an injury, according to the Mayo Clinic. This inflammation causes symptoms such as swelling, redness, stiffness and pain, especially when bending the knee to kneel or climb stairs.
Ligament Injuries
Ligaments are bands of connective tissue that attach bone to bone. The knee has four ligaments, each of which can tear or stretch due to trauma. The anterior cruciate ligament (ACL) is especially vulnerable, being located at the front of the knee. Athletes often injure the ACL during sports such as basketball, soccer and football. Ligament tears cause pain when the knee bends or supports weight, and the feeling that the knee is unstable and might give way. Ligament tears can produce a popping sound.
Tendonitis
Tendons are strong fibrous bands that connect muscle to bone. They can become inflamed by trauma, or overuse, a condition known as tendonitis. Tendonitis causes pain, swelling and an inability to fully straighten the knee.
Cartilate Tears
The cartilaginous disc that is sandwiched between the femur and tibia is called the meniscus. Tears in the meniscus can cause pain, swelling, and the sensation of the knee being stuck, or locked in place.
Baker's Cyst
The bursae in the knee are filled with a lubricant called synovial fluid. When excess synovial fluid is produced, it builds up in the bursa in the back of the knee, which swells and becomes a Baker's cyst, according to the University of Maryland Medical Center. This type of injury result in a water balloon-like swelling behind the knee, accompanied by stiffness and pain.
Dislocated Kneecap
It is possible to knock the patella out of place, causing a visible dislocation and intense pain. In these cases the patella becomes loose and movable. The area around the dislocated kneecap can become swollen and the injury makes it difficult to walk or straighten the knee.
