The knee is easily injured. These injuries are relatively easy to recognize, because the sprain of the knee joint is accompanied by severe pain and swelling.
HOW DOES A KNEE STAGE WORK?
Bones of our legs carry the weight of the whole body
It is a considerable burden, which in obese people can exceed even 100 kg. It is particularly susceptible to tibia and femur, forming the vertical leg structure. These bones must rest firmly against each other in the knee joint and withstand various curves, bending, kneeling, etc. under load. Usually this is not a problem for our body, because the knee joint is prepared for such a load.
As it usually starts ...
However, sometimes a bad "jump" when playing volleyball, hooked on something like a hard ski or roller, or just a badly placed leg causes a characteristic "crunch in the knee". Almost immediately, the pain prevents movement, soon swelling of the joint. What exactly happened to our knee? - we often ask a doctor who does not always have time to explain the essence of pathology. The more so that to understand the essence of the injury you need to learn the mechanics of the knee joint.
How is the knee joint built?
The knee joint is a movable connection of the two largest human bones - tibia and femur. This connection is made in such a way that the convex head of the femur is "placed" in the concave cup of the tibia bone. The articular socket is formed by 2 knuckles and the so-called kneecap. The surface of the head and pan covers the thick 3-4 mm cartilage. The largest thickness of the cartilage reaches the surface of the patella (5-6 mm), which facilitates cushioning of body shakes during running or jumping. To secure the correct movement - the acetabulum has a movable supplement in the form of two displaced semilunar fibrous-cartilage rings - the so-called łęgotek.
The role of the knee joint
Man's knee joint is one of the most endangered joints in the body. This is due to its location in the prolongation of two long levers, such as the femoral (upper lever) and tibial legs (lower lever), as well as frequent physical exercise heavily burdening this organ of movement. Not without significance is the fact that the knee joint is so-called hinged joint, which means the ability to move mainly in one plane - ie to bend and straighten in accordance with the direction in which we move.
Movement mechanism in the pond
When walking, running or jumping in the directions in which we move - round joint surfaces are running smoothly on each other. With each correct movement, muscles actively shrink and relax while the ligaments shrink and stretch passively. However, if we slightly change the direction of bending the leg in the joint it will be blocked. The range of knee joint movements is limited - the so-called stabilizing apparatus, which are numerous ligaments (passive) and muscles (actively). Both structures additionally, often twist and rotate, which allows for flexible blocking of unauthorized movements due to the construction of the joint. Thus, a drastic overshoot - eg due to an injury of a specific manipulation limit - results in damage to the knee joint or the stabilizing apparatus.
The point of highest risk
Stability of the knee joint is ensured by four main ligaments that bind the bone joints and 13 muscles acting on the joint. Nevertheless, under the influence of sudden overloading, excessive twisting or bending of the joint may occur as well as damage to the system of ligaments and muscle attachments stabilizing its movements.So far, it has not been possible to invent any reasonable safeguards to reduce the risk of injury to cross-bracing stabilizing the joint. It is so unfortunate that cross-ligaments can not be protected for simple biomechanical reasons - the knee is the so-called. engineer nightmare, because he is free to move and at the same time be stable.
When do we usually get a knee injury?
Sprains of the knee are most common when walking, skating or playing football, if we step on an uneven ground, while skiing, when the foot immobilized in the shoe prevents forced rotation of the whole leg. We get bruises of the knee by hitting a hard surface during falling from a bicycle, skateboard or playing ball.
Why does it hurt?
Pain caused by sprain of the knee joint is the result of rupture of ligaments or muscles and the shortly after this abundant secretion of inflammation mediators. Substances of this type irritate pain receptors.
