The knee is the largest joint in the human body. It is composed of different parts and is therefore very complex. Its nature allows people to bend and extend the knee and is thus instrumental in the movement of walking. Diseases or injuries of the knee therefore usually mean a significant restriction of movement.
What are knees?
Schematic diagram showing the anatomy and structure of the knee joint. Click to enlarge. The knee is a joint consisting of several parts that connects the thigh to the lower leg. Due to its construction, the leg can be bent and extended; without such a movable knee joint, the human leg would be stiff. Doctors refer to the knee as a so-called compound joint, because it consists of several different joint parts that together form the entire knee. The back of the knee is called the popliteal fossa. Nerves and blood vessels run through it. The knee can be damaged by incorrect or permanent stress or by injuries, such as in accidents or during sports. If this damage is permanent, surgery may be needed to preserve the mobility of the knee joint.
Anatomy and structure
The knee is located in the human body between the upper and lower legs. It represents the junction between the two legs and is designed to have a range of motion of approximately 150°. Roughly speaking, the knee consists of the femur, the tibia and the patella. These three make up the bony part of the knee. In addition, various muscles and ligaments are found inside the knee, which are responsible for the mobility and stability of the joint. The muscles are divided into extensors and flexors, among others, depending on the task they perform. The menisci, which are discs of cartilage between the bony joints, also promote the mobility of the knee.
Functions and tasks
The main function of the knee lies in the aforementioned mobility, which would not exist without the special composition of the knee joint. In particular, the ligaments located in and around the joint capsule are involved in flexion and extension. With their help, a range of motion of up to 150° is achieved (depending on whether flexion, extension or rotation movements are performed). Flexion places the greatest stress on the knee at 120° -150°, whereas rotation only takes place up to 40°. Due to its nature, the knee joint is also called a rotational hinge joint. The various components of the knee once again perform special tasks that support the function of the entire knee joint. For example, the ligaments serve to stabilize the knee, while the menisci provide a “link” between the bony parts and increase mobility. The patella’s function is to increase leverage while decreasing the resistance created when the tendons slide over the bone during movements.
Diseases
Because the knee itself is a rather unstable structure and is involved in all walking, jumping and running movements, it is not uncommon for damage or disease to occur in this area. Torn ligaments, fractures, dislocations or meniscus tears are relatively common, especially among athletes. They occur as a result of too much permanent stress or also as a result of accidents. The chances of healing depend on the type of injury and, of course, on the treatment and individual assistance of the patient. Dislocations, for example, rarely heal completely because the ligaments involved are often irreparably damaged. However, it is not only athletes who run the risk of damaging their knees. Joint wear and tear in the knee usually results from the natural aging process alone. It manifests itself as pain when walking or stretching or bending the knee. Inflammation of the knee joint or the associated bursa results from spontaneous overuse or from open wounds that lead to infection. While external injuries in the knee area do not necessarily require medical treatment, a visit to the doctor is always advisable for diseases or problems in the internal area. In this way, permanent damage can be prevented and the mobility of the knee can be maintained in the long term.
Typical and common diseases
- Knee joint osteoarthritis
- Knee pain
- Lateral ligament tear at the knee
- Cruciate ligament tear
- Runner’s knee (iliotibial band syndrome)
