The knee joint joins the thigh with the lower leg and consists of two articulations: one between the femur and tibia, and one between the femur and patella. It is the largest joint in the human body and is very complicated. The knee is a pivotal hinge joint, which permits flexion and extension as well as a slight rotation. Since in humans the knee supports nearly the whole weight of the body, it is vulnerable to both acute injury (ligament sprain, muscle strain, meniscus tear) and the development of diseases.
Knee pain can be caused by trauma, misalignment, and degeneration as well as by conditions like arthritis. The most common knee disorder is generally known as patellofemoral syndrome. The majority of minor cases of knee pain can be treated at home with rest and ice but more serious injuries do require surgical care. One form of patellofemoral syndrome involves a tissue-related problem that creates pressure and irritation in the knee (patellar compression syndrome) causing pain.
The second major class of knee disorder is Patella Tendinopathy, where the patella (knee cap) tendon becomes dysfunctional and inflamed.
Age also contributes to disorders of the knee. Particularly in older people, knee pain frequently arises due to osteoarthritis. In addition, weakening of the muscles around the knee may contribute to the problem.
Cartilage lesions can be caused by:
- Accidents (fractures)
- Muscle injuries
- The removal of a meniscus
- Anterior cruciate ligament injury
- Posterior cruciate ligament injury
- Posterolateral corner injury
- Medial knee injuries
- Considerable strain on the knee.
Any kind of work during which the knees undergo heavy stress may also be detrimental to cartilage. This is especially the case in professions in which people frequently have to walk, lift, or squat. Other causes of pain may be excessive on, and wear of, the knees, in combination with such things as muscle weakness and overweight.
Common complaints are a painful, blocked, locked or swollen knee. Sufferers sometimes feel as if their knees are about to give way, or may feel uncertain about their movement.